Ribonucleotide Reductases are enzymes that catalyze the conversion of ribonucleotides to deoxyribonucleotides, which is a crucial step in DNA synthesis and repair, utilizing a radical mechanism for this conversion.
An enzyme of the oxidoreductase class that catalyzes the formation of 2'-deoxyribonucleotides from the corresponding ribonucleotides using NADPH as the ultimate electron donor. The deoxyribonucleoside diphosphates are used in DNA synthesis. (From Dorland, 27th ed) EC 1.17.4.1.
Cytidine 5'-(trihydrogen diphosphate). A cytosine nucleotide containing two phosphate groups esterified to the sugar moiety. Synonyms: CRPP; cytidine pyrophosphate.
An antineoplastic agent that inhibits DNA synthesis through the inhibition of ribonucleoside diphosphate reductase.
A purine or pyrimidine base bonded to a DEOXYRIBOSE containing a bond to a phosphate group.
Thiosemicarbazones are organic compounds resulting from the condensation of thiosemicarbazide with a carbonyl group, characterized by the presence of a -NH-CS-NH-CO- functional structure and widely used in chelation therapy due to their ability to form stable complexes with various metal ions.
Highly reactive molecules with an unsatisfied electron valence pair. Free radicals are produced in both normal and pathological processes. They are proven or suspected agents of tissue damage in a wide variety of circumstances including radiation, damage from environment chemicals, and aging. Natural and pharmacological prevention of free radical damage is being actively investigated.
Nucleotides in which the purine or pyrimidine base is combined with ribose. (Dorland, 28th ed)
A technique applicable to the wide variety of substances which exhibit paramagnetism because of the magnetic moments of unpaired electrons. The spectra are useful for detection and identification, for determination of electron structure, for study of interactions between molecules, and for measurement of nuclear spins and moments. (From McGraw-Hill Encyclopedia of Science and Technology, 7th edition) Electron nuclear double resonance (ENDOR) spectroscopy is a variant of the technique which can give enhanced resolution. Electron spin resonance analysis can now be used in vivo, including imaging applications such as MAGNETIC RESONANCE IMAGING.
A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.
An enzyme that catalyzes the transfer of a formyl group from N10-formyltetrahydrofolate to N1-(5-phospho-D-ribosyl)glycinamide to yield N2-formyl-N1-(5-phospho-D-ribosyl)glycinamide and tetrahydrofolate. It plays a role in the de novo purine biosynthetic pathway.
Oxidoreductases that are specific for the reduction of NITRATES.
Adenine nucleotides which contain deoxyribose as the sugar moiety.
Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.
Enzymes that catalyze the reversible reduction of alpha-carboxyl group of 3-hydroxy-3-methylglutaryl-coenzyme A to yield MEVALONIC ACID.
An enzyme that utilizes NADH or NADPH to reduce FLAVINS. It is involved in a number of biological processes that require reduced flavin for their functions such as bacterial bioluminescence. Formerly listed as EC 1.6.8.1 and EC 1.5.1.29.
Enzymes that catalyze the transfer of hydroxymethyl or formyl groups. EC 2.1.2.
A FLAVOPROTEIN enzyme that catalyzes the oxidation of THIOREDOXINS to thioredoxin disulfide in the presence of NADP+. It was formerly listed as EC 1.6.4.5
The class of all enzymes catalyzing oxidoreduction reactions. The substrate that is oxidized is regarded as a hydrogen donor. The systematic name is based on donor:acceptor oxidoreductase. The recommended name will be dehydrogenase, wherever this is possible; as an alternative, reductase can be used. Oxidase is only used in cases where O2 is the acceptor. (Enzyme Nomenclature, 1992, p9)
Guanine nucleotides which contain deoxyribose as the sugar moiety.
The rate dynamics in chemical or physical systems.
Hydrogen-donating proteins that participates in a variety of biochemical reactions including ribonucleotide reduction and reduction of PEROXIREDOXINS. Thioredoxin is oxidized from a dithiol to a disulfide when acting as a reducing cofactor. The disulfide form is then reduced by NADPH in a reaction catalyzed by THIOREDOXIN REDUCTASE.
Cytosine nucleotides which contain deoxyribose as the sugar moiety.
A metallic element with atomic symbol Fe, atomic number 26, and atomic weight 55.85. It is an essential constituent of HEMOGLOBINS; CYTOCHROMES; and IRON-BINDING PROTEINS. It plays a role in cellular redox reactions and in the transport of OXYGEN.
A cytostatic triazole derivative which is not to be confused with guanazolo, the generic name for 8-azaguanine.
A family of thioltransferases that contain two active site CYSTEINE residues, which either form a disulfide (oxidized form) or a dithiol (reduced form). They function as an electron carrier in the GLUTHIONE-dependent synthesis of deoxyribonucleotides by RIBONUCLEOTIDE REDUCTASES and may play a role in the deglutathionylation of protein thiols. The oxidized forms of glutaredoxins are directly reduced by the GLUTATHIONE.
The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.
Cobamides are a class of compounds that function as cofactors in various enzymatic reactions, containing a corrin ring similar to vitamin B12, but with different substituents on the benzimidazole moiety, and can be found in certain bacteria and archaea.
A species of gram-negative bacteria isolated from MILK, cheese, and compressed yeast.
A FLAVOPROTEIN oxidoreductase that occurs both as a soluble enzyme and a membrane-bound enzyme due to ALTERNATIVE SPLICING of a single mRNA. The soluble form is present mainly in ERYTHROCYTES and is involved in the reduction of METHEMOGLOBIN. The membrane-bound form of the enzyme is found primarily in the ENDOPLASMIC RETICULUM and outer mitochondrial membrane, where it participates in the desaturation of FATTY ACIDS; CHOLESTEROL biosynthesis and drug metabolism. A deficiency in the enzyme can result in METHEMOGLOBINEMIA.
A purine or pyrimidine base bonded to DEOXYRIBOSE.
The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.
Cytosine nucleotides are organic compounds that consist of a nitrogenous base (cytosine), a pentose sugar (ribose in RNA or deoxyribose in DNA), and at least one phosphate group, playing crucial roles in genetic information storage, transmission, and expression within nucleic acids.
A group of enzymes that oxidize diverse nitrogenous substances to yield nitrite. (Enzyme Nomenclature, 1992) EC 1.
A chemical reaction in which an electron is transferred from one molecule to another. The electron-donating molecule is the reducing agent or reductant; the electron-accepting molecule is the oxidizing agent or oxidant. Reducing and oxidizing agents function as conjugate reductant-oxidant pairs or redox pairs (Lehninger, Principles of Biochemistry, 1982, p471).
Adenosine molecules which can be substituted in any position, but are lacking one hydroxyl group in the ribose part of the molecule.
Phosphate esters of THYMIDINE in N-glycosidic linkage with ribose or deoxyribose, as occurs in nucleic acids. (From Dorland, 28th ed, p1154)
A genus of the family HERPESVIRIDAE, subfamily ALPHAHERPESVIRINAE, consisting of herpes simplex-like viruses. The type species is HERPESVIRUS 1, HUMAN.
Catalyzes the oxidation of GLUTATHIONE to GLUTATHIONE DISULFIDE in the presence of NADP+. Deficiency in the enzyme is associated with HEMOLYTIC ANEMIA. Formerly listed as EC 1.6.4.2.
A flavoprotein that catalyzes the reduction of heme-thiolate-dependent monooxygenases and is part of the microsomal hydroxylating system. EC 1.6.2.4.
Single chains of amino acids that are the units of multimeric PROTEINS. Multimeric proteins can be composed of identical or non-identical subunits. One or more monomeric subunits may compose a protomer which itself is a subunit structure of a larger assembly.
Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.
An enzyme that catalyzes the oxidation and reduction of FERREDOXIN or ADRENODOXIN in the presence of NADP. EC 1.18.1.2 was formerly listed as EC 1.6.7.1 and EC 1.6.99.4.
The modification of the reactivity of ENZYMES by the binding of effectors to sites (ALLOSTERIC SITES) on the enzymes other than the substrate BINDING SITES.
The monomeric units from which DNA or RNA polymers are constructed. They consist of a purine or pyrimidine base, a pentose sugar, and a phosphate group. (From King & Stansfield, A Dictionary of Genetics, 4th ed)
A non-essential amino acid. In animals it is synthesized from PHENYLALANINE. It is also the precursor of EPINEPHRINE; THYROID HORMONES; and melanin.
Cytochrome reductases are enzymes that catalyze the transfer of electrons from donor molecules to cytochromes in electron transport chains, playing a crucial role in cellular respiration and energy production within cells.
The process by which a DNA molecule is duplicated.
A characteristic feature of enzyme activity in relation to the kind of substrate on which the enzyme or catalytic molecule reacts.
A spectroscopic technique which uses the Mossbauer effect (inelastic scattering of gamma radiation resulting from interaction with heavy nuclei) to monitor the small variations in the interaction between an atomic nucleus and its environment. Such variations may be induced by changes in temperature, pressure, chemical state, molecular conformation, molecular interaction, or physical site. It is particularly useful for studies of structure-activity relationship in metalloproteins, mobility of heavy metals, and the state of whole tissue and cell membranes.
A rare, metallic element designated by the symbol, Ga, atomic number 31, and atomic weight 69.72.
The insertion of recombinant DNA molecules from prokaryotic and/or eukaryotic sources into a replicating vehicle, such as a plasmid or virus vector, and the introduction of the resultant hybrid molecules into recipient cells without altering the viability of those cells.
Proteins prepared by recombinant DNA technology.
Nicotinamide adenine dinucleotide phosphate. A coenzyme composed of ribosylnicotinamide 5'-phosphate (NMN) coupled by pyrophosphate linkage to the 5'-phosphate adenosine 2',5'-bisphosphate. It serves as an electron carrier in a number of reactions, being alternately oxidized (NADP+) and reduced (NADPH). (Dorland, 27th ed)
The degree of similarity between sequences of amino acids. This information is useful for the analyzing genetic relatedness of proteins and species.
An enzyme that catalyzes the hydrolytic deamination of deoxycytidylic acid to deoxyuridylic acid and ammonia. It plays an important role in the regulation of the pool of deoxynucleotides in higher organisms. The enzyme also acts on some 5-substituted deoxycytidylic acids. EC 3.5.4.12.
The complete absence, or (loosely) the paucity, of gaseous or dissolved elemental oxygen in a given place or environment. (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)
Compounds and molecular complexes that consist of very large numbers of atoms and are generally over 500 kDa in size. In biological systems macromolecular substances usually can be visualized using ELECTRON MICROSCOPY and are distinguished from ORGANELLES by the lack of a membrane structure.
A trace element with atomic symbol Mn, atomic number 25, and atomic weight 54.94. It is concentrated in cell mitochondria, mostly in the pituitary gland, liver, pancreas, kidney, and bone, influences the synthesis of mucopolysaccharides, stimulates hepatic synthesis of cholesterol and fatty acids, and is a cofactor in many enzymes, including arginase and alkaline phosphatase in the liver. (From AMA Drug Evaluations Annual 1992, p2035)
Proteins found in any species of bacterium.
A uracil nucleotide containing a pyrophosphate group esterified to C5 of the sugar moiety.
A site on an enzyme which upon binding of a modulator, causes the enzyme to undergo a conformational change that may alter its catalytic or binding properties.
Models used experimentally or theoretically to study molecular shape, electronic properties, or interactions; includes analogous molecules, computer-generated graphics, and mechanical structures.
Injuries to DNA that introduce deviations from its normal, intact structure and which may, if left unrepaired, result in a MUTATION or a block of DNA REPLICATION. These deviations may be caused by physical or chemical agents and occur by natural or unnatural, introduced circumstances. They include the introduction of illegitimate bases during replication or by deamination or other modification of bases; the loss of a base from the DNA backbone leaving an abasic site; single-strand breaks; double strand breaks; and intrastrand (PYRIMIDINE DIMERS) or interstrand crosslinking. Damage can often be repaired (DNA REPAIR). If the damage is extensive, it can induce APOPTOSIS.
The facilitation of a chemical reaction by material (catalyst) that is not consumed by the reaction.
Inorganic or organic compounds that contain divalent iron.
An enzyme that catalyzes reversibly the phosphorylation of deoxycytidine with the formation of a nucleoside diphosphate and deoxycytidine monophosphate. Cytosine arabinoside can also act as an acceptor. All natural nucleoside triphosphates, except deoxycytidine triphosphate, can act as donors. The enzyme is induced by some viruses, particularly the herpes simplex virus (HERPESVIRUS HOMINIS). EC 2.7.1.74.
An enzyme of the oxidoreductase class that catalyzes the reaction 7,8-dihyrofolate and NADPH to yield 5,6,7,8-tetrahydrofolate and NADPH+, producing reduced folate for amino acid metabolism, purine ring synthesis, and the formation of deoxythymidine monophosphate. Methotrexate and other folic acid antagonists used as chemotherapeutic drugs act by inhibiting this enzyme. (Dorland, 27th ed) EC 1.5.1.3.
A group of oxidoreductases that act on NADH or NADPH. In general, enzymes using NADH or NADPH to reduce a substrate are classified according to the reverse reaction, in which NAD+ or NADP+ is formally regarded as an acceptor. This subclass includes only those enzymes in which some other redox carrier is the acceptor. (Enzyme Nomenclature, 1992, p100) EC 1.6.
Established cell cultures that have the potential to propagate indefinitely.
Deoxycytidine is a nucleoside consisting of the pentose sugar deoxyribose linked to the nitrogenous base cytosine, which plays a crucial role in DNA replication and repair processes within cells.
Virulent bacteriophage and type species of the genus T4-like phages, in the family MYOVIRIDAE. It infects E. coli and is the best known of the T-even phages. Its virion contains linear double-stranded DNA, terminally redundant and circularly permuted.
Uracil nucleotides which contain deoxyribose as the sugar moiety.
Cytidine 5'-(tetrahydrogen triphosphate). A cytosine nucleotide containing three phosphate groups esterified to the sugar moiety.
The parts of a macromolecule that directly participate in its specific combination with another molecule.
The region of an enzyme that interacts with its substrate to cause the enzymatic reaction.
Organic chemicals that form two or more coordination links with an iron ion. Once coordination has occurred, the complex formed is called a chelate. The iron-binding porphyrin group of hemoglobin is an example of a metal chelate found in biological systems.
Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control of gene action in enzyme synthesis.
The complex series of phenomena, occurring between the end of one CELL DIVISION and the end of the next, by which cellular material is duplicated and then divided between two daughter cells. The cell cycle includes INTERPHASE, which includes G0 PHASE; G1 PHASE; S PHASE; and G2 PHASE, and CELL DIVISION PHASE.
A transplantable, poorly differentiated malignant tumor which appeared originally as a spontaneous breast carcinoma in a mouse. It grows in both solid and ascitic forms.
Nucleosides containing arabinose as their sugar moiety.
Leukemia L1210 is a designation for a specific murine (mouse) leukemia cell line that was originally isolated from a female mouse with an induced acute myeloid leukemia, which is widely used as a model in cancer research, particularly for in vivo studies of drug efficacy and resistance.
A flavoprotein amine oxidoreductase that catalyzes the reversible conversion of 5-methyltetrahydrofolate to 5,10-methylenetetrahydrofolate. This enzyme was formerly classified as EC 1.1.1.171.
A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine).
A generic name for film produced from wood pulp by the viscose process. It is a thin, transparent sheeting of regenerated cellulose, moisture-proof and sometimes dyed, and used chiefly as food wrapping or as bags for dialysis. (Grant & Hackh's Chemical Dictionary, 5th ed & McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
An enzyme that catalyzes the conversion of aminoimidazole-4-carboxamide ribonucleotide to 5-formyl-aminoimidazole-4-carboxamide ribonucleotide in the purine de novo synthesis pathway. It requires the cofactor N(10)-FORMYLTETRAHYDROFOLATE as the formyl donor.
Clinical sign or symptom manifested as debility, or lack or loss of strength and energy.
The study of crystal structure using X-RAY DIFFRACTION techniques. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
A species of the genus SACCHAROMYCES, family Saccharomycetaceae, order Saccharomycetales, known as "baker's" or "brewer's" yeast. The dried form is used as a dietary supplement.
The art or process of comparing photometrically the relative intensities of the light in different parts of the spectrum.
The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain).
A pyrimidine nucleoside that is composed of the base CYTOSINE linked to the five-carbon sugar D-RIBOSE.
Small molecules that are required for the catalytic function of ENZYMES. Many VITAMINS are coenzymes.
An NAD-dependent enzyme that catalyzes the oxidation of nitrite to nitrate. It is a FLAVOPROTEIN that contains IRON and MOLYBDENUM and is involved in the first step of nitrate assimilation in PLANTS; FUNGI; and BACTERIA. It was formerly classified as EC 1.6.6.1.
This line KB is now known to be a subline of the ubiquitous KERATIN-forming tumor cell line HeLa. It was originally thought to be derived from an epidermal carcinoma of the mouth, but was subsequently found, based on isoenzyme analysis, HeLa marker chromosomes, and DNA fingerprinting, to have been established via contamination by HELA CELLS. The cells are positive for keratin by immunoperoxidase staining. KB cells have been reported to contain human papillomavirus18 (HPV-18) sequences.
Proteins that control the CELL DIVISION CYCLE. This family of proteins includes a wide variety of classes, including CYCLIN-DEPENDENT KINASES, mitogen-activated kinases, CYCLINS, and PHOSPHOPROTEIN PHOSPHATASES as well as their putative substrates such as chromatin-associated proteins, CYTOSKELETAL PROTEINS, and TRANSCRIPTION FACTORS.
Compounds or agents that combine with an enzyme in such a manner as to prevent the normal substrate-enzyme combination and the catalytic reaction.
Reductases that catalyze the reaction of peptide-L-methionine -S-oxide + thioredoxin to produce peptide-L-methionine + thioredoxin disulfide + H(2)O.
The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.
RNA sequences that serve as templates for protein synthesis. Bacterial mRNAs are generally primary transcripts in that they do not require post-transcriptional processing. Eukaryotic mRNA is synthesized in the nucleus and must be exported to the cytoplasm for translation. Most eukaryotic mRNAs have a sequence of polyadenylic acid at the 3' end, referred to as the poly(A) tail. The function of this tail is not known for certain, but it may play a role in the export of mature mRNA from the nucleus as well as in helping stabilize some mRNA molecules by retarding their degradation in the cytoplasm.
An adenine nucleotide containing three phosphate groups esterified to the sugar moiety. In addition to its crucial roles in metabolism adenosine triphosphate is a neurotransmitter.
Pyrimidines with a RIBOSE and phosphate attached that can polymerize to form DNA and RNA.
An increase in the rate of synthesis of an enzyme due to the presence of an inducer which acts to derepress the gene responsible for enzyme synthesis.
A purine nucleoside that has hypoxanthine linked by the N9 nitrogen to the C1 carbon of ribose. It is an intermediate in the degradation of purines and purine nucleosides to uric acid and in pathways of purine salvage. It also occurs in the anticodon of certain transfer RNA molecules. (Dorland, 28th ed)
Compounds that inhibit HMG-CoA reductases. They have been shown to directly lower cholesterol synthesis.
Short sequences (generally about 10 base pairs) of DNA that are complementary to sequences of messenger RNA and allow reverse transcriptases to start copying the adjacent sequences of mRNA. Primers are used extensively in genetic and molecular biology techniques.
A genus of facultatively anaerobic heterotrophic archaea, in the order THERMOPLASMALES, isolated from self-heating coal refuse piles and acid hot springs. They are thermophilic and can grow both with and without sulfur.
NAD(P)H:(quinone acceptor) oxidoreductases. A family that includes three enzymes which are distinguished by their sensitivity to various inhibitors. EC 1.6.99.2 (NAD(P)H DEHYDROGENASE (QUINONE);) is a flavoprotein which reduces various quinones in the presence of NADH or NADPH and is inhibited by dicoumarol. EC 1.6.99.5 (NADH dehydrogenase (quinone)) requires NADH, is inhibited by AMP and 2,4-dinitrophenol but not by dicoumarol or folic acid derivatives. EC 1.6.99.6 (NADPH dehydrogenase (quinone)) requires NADPH and is inhibited by dicoumarol and folic acid derivatives but not by 2,4-dinitrophenol.
A potent mutagen and carcinogen. This compound and its metabolite 4-HYDROXYAMINOQUINOLINE-1-OXIDE bind to nucleic acids. It inactivates bacteria but not bacteriophage.
The sum of the weight of all the atoms in a molecule.
Natural product isolated from Streptomyces pilosus. It forms iron complexes and is used as a chelating agent, particularly in the mesylate form.
Genetically engineered MUTAGENESIS at a specific site in the DNA molecule that introduces a base substitution, or an insertion or deletion.
The arrangement of two or more amino acid or base sequences from an organism or organisms in such a way as to align areas of the sequences sharing common properties. The degree of relatedness or homology between the sequences is predicted computationally or statistically based on weights assigned to the elements aligned between the sequences. This in turn can serve as a potential indicator of the genetic relatedness between the organisms.
The process by which ELECTRONS are transported from a reduced substrate to molecular OXYGEN. (From Bennington, Saunders Dictionary and Encyclopedia of Laboratory Medicine and Technology, 1984, p270)
Life or metabolic reactions occurring in an environment containing oxygen.
A subclass of enzymes which includes all dehydrogenases acting on primary and secondary alcohols as well as hemiacetals. They are further classified according to the acceptor which can be NAD+ or NADP+ (subclass 1.1.1), cytochrome (1.1.2), oxygen (1.1.3), quinone (1.1.5), or another acceptor (1.1.99).
The functional hereditary units of BACTERIA.
A subclass of enzymes which includes all dehydrogenases acting on carbon-carbon bonds. This enzyme group includes all the enzymes that introduce double bonds into substrates by direct dehydrogenation of carbon-carbon single bonds.
Catalyze the hydrolysis of nucleotides with the elimination of ammonia.
Inorganic or organic compounds containing trivalent iron.
An enzyme that catalyzes the reduction of 6,7-dihydropteridine to 5,6,7,8-tetrahydropteridine in the presence of NADP+. Defects in the enzyme are a cause of PHENYLKETONURIA II. Formerly listed as EC 1.6.99.7.
A low-molecular-weight (16,000) iron-free flavoprotein containing one molecule of flavin mononucleotide (FMN) and isolated from bacteria grown on an iron-deficient medium. It can replace ferredoxin in all the electron-transfer functions in which the latter is known to serve in bacterial cells.
A genus of asporogenous bacteria that is widely distributed in nature. Its organisms appear as straight to slightly curved rods and are known to be human and animal parasites and pathogens.
Proteins obtained from ESCHERICHIA COLI.
Antimetabolites that are useful in cancer chemotherapy.
Diminished or failed response of an organism, disease or tissue to the intended effectiveness of a chemical or drug. It should be differentiated from DRUG TOLERANCE which is the progressive diminution of the susceptibility of a human or animal to the effects of a drug, as a result of continued administration.
Compounds with a six membered aromatic ring containing NITROGEN. The saturated version is PIPERIDINES.
A subtype of thioredoxin reductase found primarily in the CYTOSOL.
Phase of the CELL CYCLE following G1 and preceding G2 when the entire DNA content of the nucleus is replicated. It is achieved by bidirectional replication at multiple sites along each chromosome.
An adenosine monophosphate analog in which ribose is replaced by an arabinose moiety. It is the monophosphate ester of VIDARABINE with antiviral and possibly antineoplastic properties.
A coenzyme for a number of oxidative enzymes including NADH DEHYDROGENASE. It is the principal form in which RIBOFLAVIN is found in cells and tissues.
The largest order of CRUSTACEA, comprising over 10,000 species. They are characterized by three pairs of thoracic appendages modified as maxillipeds, and five pairs of thoracic legs. The order includes the familiar shrimps, crayfish (ASTACOIDEA), true crabs (BRACHYURA), and lobsters (NEPHROPIDAE and PALINURIDAE), among others.
A class in the phylum MOLLUSCA comprised of mussels; clams; OYSTERS; COCKLES; and SCALLOPS. They are characterized by a bilaterally symmetrical hinged shell and a muscular foot used for burrowing and anchoring.

Caffeine can override the S-M checkpoint in fission yeast. (1/977)

The replication checkpoint (or 'S-M checkpoint') control prevents progression into mitosis when DNA replication is incomplete. Caffeine has been known for some time to have the capacity to override the S-M checkpoint in animal cells. We show here that caffeine also disrupts the S-M checkpoint in the fission yeast Schizosaccharomyces pombe. By contrast, no comparable effects of caffeine on the S. pombe DNA damage checkpoint were seen. S. pombe cells arrested in early S phase and then exposed to caffeine lost viability rapidly as they attempted to enter mitosis, which was accompanied by tyrosine dephosphorylation of Cdc2. Despite this, the caffeine-induced loss of viability was not blocked in a temperature-sensitive cdc2 mutant incubated at the restrictive temperature, although catastrophic mitosis was prevented under these conditions. This suggests that, in addition to S-M checkpoint control, a caffeine-sensitive function may be important for maintenance of cell viability during S phase arrest. The lethality of a combination of caffeine with the DNA replication inhibitor hydroxyurea was suppressed by overexpression of Cds1 or Chk1, protein kinases previously implicated in S-M checkpoint control and recovery from S phase arrest. In addition, the same combination of drugs was specifically tolerated in cells overexpressing either of two novel S. pombe genes isolated in a cDNA library screen. These findings should allow further molecular investigation of the regulation of S phase arrest, and may provide a useful system with which to identify novel drugs that specifically abrogate the checkpoint control.  (+info)

Increased sensitivity of hydroxyurea-resistant leukemic cells to gemcitabine. (2/977)

Tumor cell resistance to certain chemotherapeutic agents may result in cross-resistance to related antineoplastic agents. To study cross-resistance among inhibitors of ribonucleotide reductase, we developed hydroxyurea-resistant (HU-R) CCRF-CEM cells. These cells were 6-fold more resistant to hydroxyurea than the parent hydroxyurea-sensitive (HU-S) cell line and displayed an increase in the mRNA and protein of the R2 subunit of ribonucleotide reductase. We examined whether HU-R cells were cross-resistant to gemcitabine, a drug that blocks cell proliferation by inhibiting ribonucleotide reductase and incorporating itself into DNA. Contrary to our expectation, HU-R cells had an increased sensitivity to gemcitabine. The IC50 of gemcitabine was 0.061 +/- 0.03 microM for HU-R cells versus 0.16 +/- 0.02 microM for HU-S cells (P = 0.005). The cellular uptake of [3H]gemcitabine and its incorporation into DNA were increased in HU-R cells. Over an 18-h incubation with radiolabeled gemcitabine (0.25 microM), gemcitabine uptake was 286 +/- 37.3 fmol/10(6) cells for HU-R cells and 128 +/- 8.8 fmol/10(6) cells for HU-S cells (P = 0.03). The incorporation of gemcitabine into DNA was 75 +/- 6.7 fmol/10(6) cells for HU-R cells versus 22 +/- 0.6 fmol/10(6) cells for HU-S cells (P < 0.02). Our studies suggest that the increased sensitivity of HU-R cells to gemcitabine results from increased drug uptake by these cells. This, in turn, favors the incorporation of gemcitabine into DNA, resulting in enhanced cytotoxicity. The increased sensitivity of malignant cells to gemcitabine after the development of hydroxyurea resistance may be relevant to the design of chemotherapeutic trials with these drugs.  (+info)

A glycyl radical site in the crystal structure of a class III ribonucleotide reductase. (3/977)

Ribonucleotide reductases catalyze the reduction of ribonucleotides to deoxyribonucleotides. Three classes have been identified, all using free-radical chemistry but based on different cofactors. Classes I and II have been shown to be evolutionarily related, whereas the origin of anaerobic class III has remained elusive. The structure of a class III enzyme suggests a common origin for the three classes but shows differences in the active site that can be understood on the basis of the radical-initiation system and source of reductive electrons, as well as a unique protein glycyl radical site. A possible evolutionary relationship between early deoxyribonucleotide metabolism and primary anaerobic metabolism is suggested.  (+info)

Binding of Cob(II)alamin to the adenosylcobalamin-dependent ribonucleotide reductase from Lactobacillus leichmannii. Identification of dimethylbenzimidazole as the axial ligand. (4/977)

The ribonucleoside triphosphate reductase (RTPR) from Lactobacillus leichmannii catalyzes the reduction of nucleoside 5'-triphosphates to 2'-deoxynucleoside 5'-triphosphates and uses coenzyme B12, adenosylcobalamin (AdoCbl), as a cofactor. Use of a mechanism-based inhibitor, 2'-deoxy-2'-methylenecytidine 5'-triphosphate, and isotopically labeled RTPR and AdoCbl in conjunction with EPR spectroscopy has allowed identification of the lower axial ligand of cob(II)alamin when bound to RTPR. In common with the AdoCbl-dependent enzymes catalyzing irreversible heteroatom migrations and in contrast to the enzymes catalyzing reversible carbon skeleton rearrangements, the dimethylbenzimidazole moiety of the cofactor is not displaced by a protein histidine upon binding to RTPR.  (+info)

Allosteric control of three B12-dependent (class II) ribonucleotide reductases. Implications for the evolution of ribonucleotide reduction. (5/977)

Three separate classes of ribonucleotide reductases are known, each with a distinct protein structure. One common feature of all enzymes is that a single protein generates each of the four deoxyribonucleotides. Class I and III enzymes contain an allosteric substrate specificity site capable of binding effectors (ATP or various deoxyribonucleoside triphosphates) that direct enzyme specificity. Some (but not all) enzymes contain a second allosteric site that binds only ATP or dATP. Binding of dATP to this site inhibits the activity of these enzymes. X-ray crystallography has localized the two sites within the structure of the Escherichia coli class I enzyme and identified effector-binding amino acids. Here, we have studied the regulation of three class II enzymes, one from the archaebacterium Thermoplasma acidophilum and two from eubacteria (Lactobacillus leichmannii and Thermotoga maritima). Each enzyme has an allosteric site that binds ATP or various deoxyribonucleoside triphosphates and that regulates its substrate specificity according to the same rules as for class I and III enzymes. dATP does not inhibit enzyme activity, suggesting the absence of a second active allosteric site. For the L. leichmannii and T. maritima enzymes, binding experiments also indicate the presence of only one allosteric site. Their primary sequences suggest that these enzymes lack the structural requirements for a second site. In contrast, the T. acidophilum enzyme binds dATP at two separate sites, and its sequence contains putative effector-binding amino acids for a second site. The presence of a second site without apparent physiological function leads to the hypothesis that a functional site was present early during the evolution of ribonucleotide reductases, but that its function was lost from the T. acidophilum enzyme. The other two B12 enzymes lost not only the function, but also the structural basis for the site. Also a large subgroup (Ib) of class I enzymes, but none of the investigated class III enzymes, has lost this site. This is further indirect evidence that class II and I enzymes may have arisen by divergent evolution from class III enzymes.  (+info)

Enzyme-mononucleotide interactions: three different folds share common structural elements for ATP recognition. (6/977)

Three ATP-dependent enzymes with different folds, cAMP-dependent protein kinase, D-Ala:D-Ala ligase and the alpha-subunit of the alpha2beta2 ribonucleotide reductase, have a similar organization of their ATP-binding sites. The most meaningful similarity was found over 23 structurally equivalent residues in each protein and includes three strands each from their beta-sheets, in addition to a connecting loop. The equivalent secondary structure elements in each of these enzymes donate four amino acids forming key hydrogen bonds responsible for the common orientation of the "AMP" moieties of their ATP-ligands. One lysine residue conserved throughout the three families binds the alpha-phosphate in each protein. The common fragments of structure also position some, but not all, of the equivalent residues involved in hydrophobic contacts with the adenine ring. These examples of convergent evolution reinforce the view that different proteins can fold in different ways to produce similar structures locally, and nature can take advantage of these features when structure and function demand it, as shown here for the common mode of ATP-binding by three unrelated proteins.  (+info)

The activation of ribonucleotide reductase in animal organs as the cellular response against the treatment with DNA-damaging factors and the influence of radioprotectors on this effect. (7/977)

Cellular requirements for deoxyribonucleotide (dNTP) pools during DNA synthesis are related to ensuring of the accuracy of DNA copying during replication and repair. This paper covers some problems on the reactions of dNTP synthesis system in organs of animals against the treatment with DNA-damaging agents. Ribonucleoside diphosphate reductase (NDPR) is the key enzyme for the synthesis of dNTP, since it catalyses the reductive conversion of ribonucleotides to deoxyribonucleotides. The results obtained show that the rapid and transient increase in NDPR activity in animal organs occurs as cellular response against the treatment with DNA-damaging agents (SOS-type activation). We have also found the intensive radioprotector-stimulated activation of deoxyribonucleotide synthesis as well as DNA and protein synthesis in mice organs within 3 days after the administration of two radioprotectors, indralin and indometaphen, that provide the high animal survival. Our studies suggest that these effects are the most important steps in the protective mechanism of the radioprotectors and are responsible for the high animal survival.  (+info)

Immunogenicity of herpes simplex virus type 1 mutants containing deletions in one or more alpha-genes: ICP4, ICP27, ICP22, and ICP0. (8/977)

Replication defective mutants of HSV have been proposed both as vaccine candidates and as vehicles for gene therapy because of their inability to produce infectious progeny. The immunogenicity of these HSV replication mutants, at both qualitative and quantitative levels, will directly determine their effectiveness for either of these applications. We have previously reported (Brehm et al., J. Virol., 71, 3534, 1997) that a replication defective mutant of HSV-1, which expresses a substantial level of viral genes without producing virus particles, is as efficient as wild-type HSV-1 in eliciting an HSV-specific cytotoxic T-lymphocyte (CTL) response. In this report, we have further evaluated the immunogenic potential of HSV-1-derived replication defective mutants by examining the generation of HSV-specific CTL following immunization with viruses that are severely restricted in viral gene expression due to mutations in one or more HSV alpha genes (ICP4, ICP27, ICP22, and ICP0). To measure the CTL responses induced by the HSV alpha-mutants, we have targeted two H-2Kb-restricted CTL epitopes: an epitope in a virion protein, gB (498-505), and an epitope in a nonvirion protein, ribonucleotide reductase (RR1 822-829). The HSV mutants used in this study are impaired in their ability to express gB while a majority of them still express RR1. Our findings demonstrate that a single immunization with these mutants is able to generate a strong CTL response not only to RR1 822-829, but also to gB498-505 despite their inability to express wild-type levels of gB. Furthermore, a single immunization with any individual mutant can also provide immune protection against HSV challenge. These results suggest that mutants which are restricted in gene expression may be used as effective immunogens in vivo.  (+info)

Ribonucleotide Reductases (RNRs) are enzymes that play a crucial role in DNA synthesis and repair. They catalyze the conversion of ribonucleotides to deoxyribonucleotides, which are the building blocks of DNA. This process involves the reduction of the 2'-hydroxyl group of the ribose sugar to a hydrogen, resulting in the formation of deoxyribose.

RNRs are highly regulated and exist in various forms across different species. They are divided into three classes (I, II, and III) based on their structure, mechanism, and cofactor requirements. Class I RNRs are further divided into two subclasses (Ia and Ib), which differ in their active site architecture and regulation.

Class Ia RNRs, found in eukaryotes and some bacteria, contain a stable tyrosyl radical that acts as the catalytic center for hydrogen abstraction. Class Ib RNRs, found in many bacteria, use a pair of iron centers to perform the same function. Class II RNRs are present in some bacteria and archaea and utilize adenosine triphosphate (ATP) as a cofactor for reduction. Class III RNRs, found in anaerobic bacteria and archaea, use a unique mechanism involving a radical S-adenosylmethionine (SAM) cofactor to facilitate the reduction reaction.

RNRs are essential for DNA replication and repair, and their dysregulation has been linked to various diseases, including cancer and neurodegenerative disorders. Therefore, understanding the structure, function, and regulation of RNRs is of great interest in biochemistry, molecular biology, and medicine.

Ribonucleoside Diphosphate Reductase (RNR) is an enzyme that plays a crucial role in the regulation of DNA synthesis and repair. It catalyzes the conversion of ribonucleoside diphosphates (NDPs) to deoxyribonucleoside diphosphates (dNDPs), which are the building blocks of DNA. This reaction is essential for the synthesis of new DNA strands during replication and repair processes. The enzyme's activity is tightly regulated, as it must be carefully controlled to prevent errors in DNA synthesis that could lead to mutations and genomic instability. RNR is a target for chemotherapeutic agents due to its essential role in DNA synthesis.

Cytidine diphosphate (CDP) is a nucleotide that is a constituent of coenzymes and plays a role in the synthesis of lipids, such as phosphatidylcholine and sphingomyelin, which are important components of cell membranes. It is formed from cytidine monophosphate (CMP) through the addition of a second phosphate group by the enzyme CTP synthase. CDP can also be converted to other nucleotides, such as uridine diphosphate (UDP) and deoxythymidine diphosphate (dTDP), through the action of various enzymes. These nucleotides play important roles in the biosynthesis of carbohydrates, lipids, and other molecules in the cell.

Hydroxyurea is an antimetabolite drug that is primarily used in the treatment of myeloproliferative disorders such as chronic myelogenous leukemia (CML), essential thrombocythemia, and polycythemia vera. It works by interfering with the synthesis of DNA, which inhibits the growth of cancer cells.

In addition to its use in cancer therapy, hydroxyurea is also used off-label for the management of sickle cell disease. In this context, it helps to reduce the frequency and severity of painful vaso-occlusive crises by increasing the production of fetal hemoglobin (HbF), which decreases the formation of sickled red blood cells.

The medical definition of hydroxyurea is:

A hydantoin derivative and antimetabolite that inhibits ribonucleoside diphosphate reductase, thereby interfering with DNA synthesis. It has been used as an antineoplastic agent, particularly in the treatment of myeloproliferative disorders, and more recently for the management of sickle cell disease to reduce the frequency and severity of painful vaso-occlusive crises by increasing fetal hemoglobin production.

Deoxyribonucleotides are the building blocks of DNA (deoxyribonucleic acid). They consist of a deoxyribose sugar, a phosphate group, and one of four nitrogenous bases: adenine (A), guanine (G), cytosine (C), or thymine (T). A deoxyribonucleotide is formed when a nucleotide loses a hydroxyl group from its sugar molecule. In DNA, deoxyribonucleotides link together to form a long, double-helix structure through phosphodiester bonds between the sugar of one deoxyribonucleotide and the phosphate group of another. The sequence of these nucleotides carries genetic information that is essential for the development and function of all known living organisms and many viruses.

Thiosemicarbazones are a class of organic compounds that contain the functional group R-NH-CS-N=CNR', where R and R' are organic radicals. These compounds have been widely studied due to their various biological activities, including antiviral, antibacterial, and anticancer properties. They can form complexes with metal ions, which can also exhibit interesting biological activity. Thiosemicarbazones have the ability to act as chelating agents, forming stable coordination compounds with many metal ions. This property has been exploited in the development of new drugs and diagnostic agents.

Free radicals are molecules or atoms that have one or more unpaired electrons in their outermost shell, making them highly reactive. They can be formed naturally in the body through processes such as metabolism and exercise, or they can come from external sources like pollution, radiation, and certain chemicals. Free radicals can cause damage to cells and contribute to the development of various diseases, including cancer, cardiovascular disease, and neurodegenerative disorders. Antioxidants are substances that can neutralize free radicals and help protect against their harmful effects.

Ribonucleotides are organic compounds that consist of a ribose sugar, a phosphate group, and a nitrogenous base. They are the building blocks of RNA (ribonucleic acid), one of the essential molecules in all living organisms. The nitrogenous bases found in ribonucleotides include adenine, uracil, guanine, and cytosine. These molecules play crucial roles in various biological processes, such as protein synthesis, gene expression, and cellular energy production. Ribonucleotides can also be involved in cell signaling pathways and serve as important cofactors for enzymatic reactions.

Electron Spin Resonance (ESR) Spectroscopy, also known as Electron Paramagnetic Resonance (EPR) Spectroscopy, is a technique used to investigate materials with unpaired electrons. It is based on the principle of absorption of energy by the unpaired electrons when they are exposed to an external magnetic field and microwave radiation.

In this technique, a sample is placed in a magnetic field and microwave radiation is applied. The unpaired electrons in the sample absorb energy and change their spin state when the energy of the microwaves matches the energy difference between the spin states. This absorption of energy is recorded as a function of the magnetic field strength, producing an ESR spectrum.

ESR spectroscopy can provide information about the number, type, and behavior of unpaired electrons in a sample, as well as the local environment around the electron. It is widely used in physics, chemistry, and biology to study materials such as free radicals, transition metal ions, and defects in solids.

'Escherichia coli' (E. coli) is a type of gram-negative, facultatively anaerobic, rod-shaped bacterium that commonly inhabits the intestinal tract of humans and warm-blooded animals. It is a member of the family Enterobacteriaceae and one of the most well-studied prokaryotic model organisms in molecular biology.

While most E. coli strains are harmless and even beneficial to their hosts, some serotypes can cause various forms of gastrointestinal and extraintestinal illnesses in humans and animals. These pathogenic strains possess virulence factors that enable them to colonize and damage host tissues, leading to diseases such as diarrhea, urinary tract infections, pneumonia, and sepsis.

E. coli is a versatile organism with remarkable genetic diversity, which allows it to adapt to various environmental niches. It can be found in water, soil, food, and various man-made environments, making it an essential indicator of fecal contamination and a common cause of foodborne illnesses. The study of E. coli has contributed significantly to our understanding of fundamental biological processes, including DNA replication, gene regulation, and protein synthesis.

Phosphoribosylglycinamide formyltransferase (PGTF) is an enzyme involved in the biosynthesis of purine nucleotides, which are essential components of DNA and RNA. The systematic medical definition of PGTF is:

"An enzyme that catalyzes the transfer of a formyl group from 10-formyltetrahydrofolate to the amino group of phosphoribosylglycinamide, forming N-formylphosphoribosylglycinamide and tetrahydrofolate as byproducts. This reaction is the fourth step in the de novo synthesis pathway of purine nucleotides."

PGTF's gene name is GART (Glycinamide Ribonucleotide Transformylase), and it is located on human chromosome 10q24.32-q25.1. Mutations in the GART gene can lead to a rare autosomal recessive disorder called Lesch-Nyhan syndrome, which is characterized by hyperuricemia, neurological symptoms, and self-mutilating behavior.

Nitrate reductases are a group of enzymes that catalyze the reduction of nitrate (NO3-) to nitrite (NO2-). This process is an essential part of the nitrogen cycle, where nitrate serves as a terminal electron acceptor in anaerobic respiration for many bacteria and archaea. In plants, this enzyme plays a crucial role in nitrogen assimilation by reducing nitrate to ammonium (NH4+), which can then be incorporated into organic compounds. Nitrate reductases require various cofactors, such as molybdenum, heme, and/or FAD, for their activity. There are three main types of nitrate reductases: membrane-bound (which use menaquinol as an electron donor), cytoplasmic (which use NADH or NADPH as an electron donor), and assimilatory (which also use NADH or NADPH as an electron donor).

Deoxyadenine nucleotides are the chemical components that make up DNA, one of the building blocks of life. Specifically, deoxyadenine nucleotides contain a sugar molecule called deoxyribose, a phosphate group, and the nitrogenous base adenine. Adenine always pairs with thymine in DNA through hydrogen bonding. Together, these components form the building blocks of the genetic code that determines many of an organism's traits and characteristics.

Molecular sequence data refers to the specific arrangement of molecules, most commonly nucleotides in DNA or RNA, or amino acids in proteins, that make up a biological macromolecule. This data is generated through laboratory techniques such as sequencing, and provides information about the exact order of the constituent molecules. This data is crucial in various fields of biology, including genetics, evolution, and molecular biology, allowing for comparisons between different organisms, identification of genetic variations, and studies of gene function and regulation.

Hydroxymethylglutaryl CoA (HMG-CoA) reductase is an enzyme that plays a crucial role in the synthesis of cholesterol in the body. It is found in the endoplasmic reticulum of cells and catalyzes the conversion of HMG-CoA to mevalonic acid, which is a key rate-limiting step in the cholesterol biosynthetic pathway.

The reaction catalyzed by HMG-CoA reductase is as follows:

HMG-CoA + 2 NADPH + 2 H+ → mevalonic acid + CoA + 2 NADP+

This enzyme is the target of statin drugs, which are commonly prescribed to lower cholesterol levels in the treatment of cardiovascular diseases. Statins work by inhibiting HMG-CoA reductase, thereby reducing the production of cholesterol in the body.

Flavin Mononucleotide (FMN) Reductase is an enzyme that catalyzes the reduction of FMN to FMNH2 using NADH or NADPH as an electron donor. This enzyme plays a crucial role in the electron transport chain and is involved in various redox reactions within the cell. It is found in many organisms, including bacteria, fungi, plants, and animals. In humans, FMN Reductase is encoded by the RIBFLR gene and is primarily located in the mitochondria. Defects in this enzyme can lead to various metabolic disorders.

Hydroxymethyl and Formyl Transferases are a class of enzymes that catalyze the transfer of hydroxymethyl or formyl groups from one molecule to another. These enzymes play important roles in various metabolic pathways, including the synthesis and modification of nucleotides, amino acids, and other biomolecules.

One example of a Hydroxymethyl Transferase is DNA methyltransferase (DNMT), which catalyzes the transfer of a methyl group from S-adenosylmethionine (SAM) to the 5-carbon of cytosine residues in DNA, forming 5-methylcytosine. This enzyme can also function as a Hydroxymethyl Transferase by catalyzing the transfer of a hydroxymethyl group from SAM to cytosine residues, forming 5-hydroxymethylcytosine.

Formyl Transferases are another class of enzymes that catalyze the transfer of formyl groups from one molecule to another. One example is formyltransferase domain containing protein 1 (FTCD1), which catalyzes the transfer of a formyl group from 10-formyltetrahydrofolate to methionine, forming N5-formiminotetrahydrofolate and methionine semialdehyde.

These enzymes are essential for maintaining proper cellular function and are involved in various physiological processes, including gene regulation, DNA repair, and metabolism. Dysregulation of these enzymes has been implicated in several diseases, including cancer, neurological disorders, and cardiovascular disease.

Thioredoxin-disulfide reductase (Txnrd, TrxR) is an enzyme that belongs to the pyridine nucleotide-disulfide oxidoreductase family. It plays a crucial role in maintaining the intracellular redox balance by reducing disulfide bonds in proteins and keeping them in their reduced state. This enzyme utilizes NADPH as an electron donor to reduce thioredoxin (Trx), which then transfers its electrons to various target proteins, thereby regulating their activity, protein folding, and antioxidant defense mechanisms.

Txnrd is essential for several cellular processes, including DNA synthesis, gene expression, signal transduction, and protection against oxidative stress. Dysregulation of Txnrd has been implicated in various pathological conditions, such as cancer, neurodegenerative diseases, and inflammatory disorders. Therefore, understanding the function and regulation of this enzyme is of great interest for developing novel therapeutic strategies.

Oxidoreductases are a class of enzymes that catalyze oxidation-reduction reactions, which involve the transfer of electrons from one molecule (the reductant) to another (the oxidant). These enzymes play a crucial role in various biological processes, including energy production, metabolism, and detoxification.

The oxidoreductase-catalyzed reaction typically involves the donation of electrons from a reducing agent (donor) to an oxidizing agent (acceptor), often through the transfer of hydrogen atoms or hydride ions. The enzyme itself does not undergo any permanent chemical change during this process, but rather acts as a catalyst to lower the activation energy required for the reaction to occur.

Oxidoreductases are classified and named based on the type of electron donor or acceptor involved in the reaction. For example, oxidoreductases that act on the CH-OH group of donors are called dehydrogenases, while those that act on the aldehyde or ketone groups are called oxidases. Other examples include reductases, peroxidases, and catalases.

Understanding the function and regulation of oxidoreductases is important for understanding various physiological processes and developing therapeutic strategies for diseases associated with impaired redox homeostasis, such as cancer, neurodegenerative disorders, and cardiovascular disease.

Deoxyguanine nucleotides are chemical compounds that are the building blocks of DNA, one of the fundamental molecules of life. Specifically, deoxyguanine nucleotides contain a sugar molecule called deoxyribose, a phosphate group, and the nitrogenous base guanine.

Guanine is one of the four nitrogenous bases found in DNA, along with adenine, thymine, and cytosine. In DNA, guanine always pairs with cytosine through hydrogen bonding, forming a stable base pair that is crucial for maintaining the structure and integrity of the genetic code.

Deoxyguanine nucleotides are synthesized in cells during the process of DNA replication, which occurs prior to cell division. During replication, the double helix structure of DNA is unwound, and each strand serves as a template for the synthesis of a new complementary strand. Deoxyguanine nucleotides are added to the growing chain of nucleotides by an enzyme called DNA polymerase, which catalyzes the formation of a phosphodiester bond between the deoxyribose sugar of one nucleotide and the phosphate group of the next.

Abnormalities in the synthesis or metabolism of deoxyguanine nucleotides can lead to genetic disorders and cancer. For example, mutations in genes that encode enzymes involved in the synthesis of deoxyguanine nucleotides have been linked to inherited diseases such as xeroderma pigmentosum and Bloom syndrome, which are characterized by increased sensitivity to sunlight and a predisposition to cancer. Additionally, defects in the repair of damaged deoxyguanine nucleotides can lead to the accumulation of mutations and contribute to the development of cancer.

In the context of medicine and pharmacology, "kinetics" refers to the study of how a drug moves throughout the body, including its absorption, distribution, metabolism, and excretion (often abbreviated as ADME). This field is called "pharmacokinetics."

1. Absorption: This is the process of a drug moving from its site of administration into the bloodstream. Factors such as the route of administration (e.g., oral, intravenous, etc.), formulation, and individual physiological differences can affect absorption.

2. Distribution: Once a drug is in the bloodstream, it gets distributed throughout the body to various tissues and organs. This process is influenced by factors like blood flow, protein binding, and lipid solubility of the drug.

3. Metabolism: Drugs are often chemically modified in the body, typically in the liver, through processes known as metabolism. These changes can lead to the formation of active or inactive metabolites, which may then be further distributed, excreted, or undergo additional metabolic transformations.

4. Excretion: This is the process by which drugs and their metabolites are eliminated from the body, primarily through the kidneys (urine) and the liver (bile).

Understanding the kinetics of a drug is crucial for determining its optimal dosing regimen, potential interactions with other medications or foods, and any necessary adjustments for special populations like pediatric or geriatric patients, or those with impaired renal or hepatic function.

Thioredoxins are a group of small proteins that contain a redox-active disulfide bond and play a crucial role in the redox regulation of cellular processes. They function as electron donors and help to maintain the intracellular reducing environment by reducing disulfide bonds in other proteins, thereby regulating their activity. Thioredoxins also have antioxidant properties and protect cells from oxidative stress by scavenging reactive oxygen species (ROS) and repairing oxidatively damaged proteins. They are widely distributed in various organisms, including bacteria, plants, and animals, and are involved in many physiological processes such as DNA synthesis, protein folding, and apoptosis.

Deoxycytosine nucleotides are chemical compounds that are the building blocks of DNA, one of the two nucleic acids found in cells. Specifically, deoxycytosine nucleotides consist of a deoxyribose sugar, a phosphate group, and the nitrogenous base cytosine.

In DNA, deoxycytosine nucleotides pair with deoxyguanosine nucleotides through hydrogen bonding between the bases to form a stable structure that stores genetic information. The synthesis of deoxycytosine nucleotides is tightly regulated in cells to ensure proper replication and repair of DNA.

Disruptions in the regulation of deoxycytosine nucleotide metabolism can lead to various genetic disorders, including mitochondrial DNA depletion syndromes and cancer. Therefore, understanding the biochemistry and regulation of deoxycytosine nucleotides is crucial for developing effective therapies for these conditions.

In the context of medicine, iron is an essential micromineral and key component of various proteins and enzymes. It plays a crucial role in oxygen transport, DNA synthesis, and energy production within the body. Iron exists in two main forms: heme and non-heme. Heme iron is derived from hemoglobin and myoglobin in animal products, while non-heme iron comes from plant sources and supplements.

The recommended daily allowance (RDA) for iron varies depending on age, sex, and life stage:

* For men aged 19-50 years, the RDA is 8 mg/day
* For women aged 19-50 years, the RDA is 18 mg/day
* During pregnancy, the RDA increases to 27 mg/day
* During lactation, the RDA for breastfeeding mothers is 9 mg/day

Iron deficiency can lead to anemia, characterized by fatigue, weakness, and shortness of breath. Excessive iron intake may result in iron overload, causing damage to organs such as the liver and heart. Balanced iron levels are essential for maintaining optimal health.

I'm sorry for any confusion, but "Guanazole" does not have a widely recognized medical definition or use. It is possible that you may be referring to "Guanzone," which is an obsolete term for a class of medications known as guanidines. These were once used in the treatment of heart conditions, but their use has been largely discontinued due to safer and more effective alternatives.

If you meant something else or if this doesn't answer your question, please provide more context or clarify your request.

Glutaredoxins (Grxs) are small, ubiquitous proteins that belong to the thioredoxin superfamily. They play a crucial role in maintaining the redox balance within cells by catalyzing the reversible reduction of disulfide bonds and mixed disulfides between protein thiols and low molecular weight compounds, using glutathione (GSH) as a reducing cofactor.

Glutaredoxins are involved in various cellular processes, such as:

1. DNA synthesis and repair
2. Protein folding and degradation
3. Antioxidant defense
4. Regulation of enzyme activities
5. Iron-sulfur cluster biogenesis

There are two main classes of glutaredoxins, Grx1 and Grx2, which differ in their active site sequences and functions. In humans, Grx1 is primarily located in the cytosol, while Grx2 is found in both the cytosol and mitochondria.

The medical relevance of glutaredoxins lies in their role as antioxidant proteins that protect cells from oxidative stress and maintain cellular redox homeostasis. Dysregulation of glutaredoxin function has been implicated in several pathological conditions, including neurodegenerative diseases, cancer, and aging-related disorders.

An amino acid sequence is the specific order of amino acids in a protein or peptide molecule, formed by the linking of the amino group (-NH2) of one amino acid to the carboxyl group (-COOH) of another amino acid through a peptide bond. The sequence is determined by the genetic code and is unique to each type of protein or peptide. It plays a crucial role in determining the three-dimensional structure and function of proteins.

Cobamides are a class of compounds that are structurally related to vitamin B12 (cobalamin). They consist of a corrin ring, which is a large heterocyclic ring made up of four pyrrole rings, and a cobalt ion in the center. The lower axial ligand of the cobalt ion can be a variety of different groups, including cyano, hydroxo, methyl, or 5'-deoxyadenosyl groups.

Cobamides are involved in a number of important biological processes, including the synthesis of amino acids and nucleotides, the metabolism of fatty acids and cholesterol, and the regulation of gene expression. They function as cofactors for enzymes called cobamide-dependent methyltransferases, which transfer methyl groups (CH3) from one molecule to another.

Cobamides are found in a wide variety of organisms, including bacteria, archaea, and eukaryotes. In humans, the most important cobamide is vitamin B12, which is essential for the normal functioning of the nervous system and the production of red blood cells. Vitamin B12 deficiency can lead to neurological problems and anemia.

I'm sorry for any confusion, but 'Lactobacillus leichmannii' is not a currently valid species name in the genus Lactobacillus. It was previously used to refer to a particular species of lactic acid bacteria, but recent taxonomic revisions have led to its renaming. The organism that was once known as 'Lactobacillus leichmannii' is now classified as Lacticaseibacillus rhamnosus.

Lacticaseibacillus rhamnosus is a gram-positive, facultatively anaerobic, non-spore forming rod that produces lactic acid as one of its major end products. It's commonly found in the human gastrointestinal tract and is often used in various industrial applications, including food production and probiotics.

Deoxyribonucleosides are chemical compounds that constitute the basic building blocks of DNA, one of the two nucleic acids found in cells. They consist of a sugar molecule called deoxyribose, a nitrogenous base (either adenine, guanine, cytosine, or thymine), and a phosphate group.

The nitrogenous base is attached to the 1' carbon atom of the deoxyribose sugar, forming a glycosidic bond. The phosphate group is linked to the 5' carbon atom of the deoxyribose sugar through an ester linkage, creating a phosphodiester bond with another deoxyribonucleoside.

When multiple deoxyribonucleosides are joined together through their phosphate groups, they form a polynucleotide chain, which is the backbone of DNA. The sequence of nitrogenous bases along this chain encodes genetic information that determines the characteristics and functions of living organisms.

Deoxyribonucleosides play a crucial role in various biological processes, including DNA replication, repair, and transcription. They are also used as therapeutic agents for the treatment of certain genetic disorders and cancer.

A base sequence in the context of molecular biology refers to the specific order of nucleotides in a DNA or RNA molecule. In DNA, these nucleotides are adenine (A), guanine (G), cytosine (C), and thymine (T). In RNA, uracil (U) takes the place of thymine. The base sequence contains genetic information that is transcribed into RNA and ultimately translated into proteins. It is the exact order of these bases that determines the genetic code and thus the function of the DNA or RNA molecule.

Cytosine nucleotides are the chemical units or building blocks that make up DNA and RNA, one of the four nitrogenous bases that form the rung of the DNA ladder. A cytosine nucleotide is composed of a cytosine base attached to a sugar molecule (deoxyribose in DNA and ribose in RNA) and at least one phosphate group. The sequence of these nucleotides determines the genetic information stored in an organism's genome. In particular, cytosine nucleotides pair with guanine nucleotides through hydrogen bonding to form base pairs that are held together by weak interactions. This pairing is specific and maintains the structure and integrity of the DNA molecule during replication and transcription.

Nitrite reductases are a group of enzymes that catalyze the reduction of nitrite (NO2-) to nitric oxide (NO). This reaction is an important part of the nitrogen cycle, particularly in denitrification and dissimilatory nitrate reduction to ammonium (DNRA) processes. Nitrite reductases can be classified into two main types based on their metal co-factors: copper-containing nitrite reductases (CuNiRs) and cytochrome cd1 nitrite reductases. CuNiRs are typically found in bacteria and fungi, while cytochrome cd1 nitrite reductases are primarily found in bacteria. These enzymes play a crucial role in the global nitrogen cycle and have potential implications for environmental and medical research.

Oxidation-Reduction (redox) reactions are a type of chemical reaction involving a transfer of electrons between two species. The substance that loses electrons in the reaction is oxidized, and the substance that gains electrons is reduced. Oxidation and reduction always occur together in a redox reaction, hence the term "oxidation-reduction."

In biological systems, redox reactions play a crucial role in many cellular processes, including energy production, metabolism, and signaling. The transfer of electrons in these reactions is often facilitated by specialized molecules called electron carriers, such as nicotinamide adenine dinucleotide (NAD+/NADH) and flavin adenine dinucleotide (FAD/FADH2).

The oxidation state of an element in a compound is a measure of the number of electrons that have been gained or lost relative to its neutral state. In redox reactions, the oxidation state of one or more elements changes as they gain or lose electrons. The substance that is oxidized has a higher oxidation state, while the substance that is reduced has a lower oxidation state.

Overall, oxidation-reduction reactions are fundamental to the functioning of living organisms and are involved in many important biological processes.

Deoxyadenosine is a chemical compound that is a component of DNA, one of the nucleic acids that make up the genetic material of living organisms. Specifically, deoxyadenosine is a nucleoside, which is a molecule consisting of a sugar (in this case, deoxyribose) bonded to a nitrogenous base (in this case, adenine).

Deoxyribonucleosides like deoxyadenosine are the building blocks of DNA, along with phosphate groups. In DNA, deoxyadenosine pairs with thymidine via hydrogen bonds to form one of the four rungs in the twisted ladder structure of the double helix.

It is important to note that there is a similar compound called adenosine, which contains an extra oxygen atom on the sugar molecule (making it a ribonucleoside) and is a component of RNA, another nucleic acid involved in protein synthesis and other cellular processes.

Thymine nucleotides are biochemical components that play a crucial role in the structure and function of DNA (deoxyribonucleic acid), which is the genetic material present in living organisms. A thymine nucleotide consists of three parts: a sugar molecule called deoxyribose, a phosphate group, and a nitrogenous base called thymine.

Thymine is one of the four nucleobases in DNA, along with adenine, guanine, and cytosine. It specifically pairs with adenine through hydrogen bonding, forming a base pair that is essential for maintaining the structure and stability of the double helix. Thymine nucleotides are linked together by phosphodiester bonds between the sugar molecules of adjacent nucleotides, creating a long, linear polymer known as a DNA strand.

In summary, thymine nucleotides are building blocks of DNA that consist of deoxyribose, a phosphate group, and the nitrogenous base thymine, which pairs with adenine in the double helix structure.

Simplexvirus is a genus of viruses in the family Herpesviridae, subfamily Alphaherpesvirinae. This genus contains two species: Human alphaherpesvirus 1 (also known as HSV-1 or herpes simplex virus type 1) and Human alphaherpesvirus 2 (also known as HSV-2 or herpes simplex virus type 2). These viruses are responsible for causing various medical conditions, most commonly oral and genital herpes. They are characterized by their ability to establish lifelong latency in the nervous system and reactivate periodically to cause recurrent symptoms.

Glutathione reductase (GR) is an enzyme that plays a crucial role in maintaining the cellular redox state. The primary function of GR is to reduce oxidized glutathione (GSSG) to its reduced form (GSH), which is an essential intracellular antioxidant. This enzyme utilizes nicotinamide adenine dinucleotide phosphate (NADPH) as a reducing agent in the reaction, converting it to NADP+. The medical definition of Glutathione Reductase is:

Glutathione reductase (GSR; EC 1.8.1.7) is a homodimeric flavoprotein that catalyzes the reduction of oxidized glutathione (GSSG) to reduced glutathione (GSH) in the presence of NADPH as a cofactor. This enzyme is essential for maintaining the cellular redox balance and protecting cells from oxidative stress by regenerating the active form of glutathione, a vital antioxidant and detoxifying agent.

NADPH-ferrihemoprotein reductase, also known as diaphorase or NO synthase reductase, is an enzyme that catalyzes the reduction of ferrihemoproteins using NADPH as a reducing cofactor. This reaction plays a crucial role in various biological processes such as the detoxification of certain compounds and the regulation of cellular signaling pathways.

The systematic name for this enzyme is NADPH:ferrihemoprotein oxidoreductase, and it belongs to the family of oxidoreductases that use NADH or NADPH as electron donors. The reaction catalyzed by this enzyme can be represented as follows:

NADPH + H+ + ferrihemoprotein ↔ NADP+ + ferrohemoprotein

In this reaction, the ferric (FeIII) form of hemoproteins is reduced to its ferrous (FeII) form by accepting electrons from NADPH. This enzyme is widely distributed in various tissues and organisms, including bacteria, fungi, plants, and animals. It has been identified as a component of several multi-enzyme complexes involved in different metabolic pathways, such as nitric oxide synthase (NOS) and cytochrome P450 reductase.

In summary, NADPH-ferrihemoprotein reductase is an essential enzyme that catalyzes the reduction of ferrihemoproteins using NADPH as a reducing agent, playing a critical role in various biological processes and metabolic pathways.

A protein subunit refers to a distinct and independently folding polypeptide chain that makes up a larger protein complex. Proteins are often composed of multiple subunits, which can be identical or different, that come together to form the functional unit of the protein. These subunits can interact with each other through non-covalent interactions such as hydrogen bonds, ionic bonds, and van der Waals forces, as well as covalent bonds like disulfide bridges. The arrangement and interaction of these subunits contribute to the overall structure and function of the protein.

A mutation is a permanent change in the DNA sequence of an organism's genome. Mutations can occur spontaneously or be caused by environmental factors such as exposure to radiation, chemicals, or viruses. They may have various effects on the organism, ranging from benign to harmful, depending on where they occur and whether they alter the function of essential proteins. In some cases, mutations can increase an individual's susceptibility to certain diseases or disorders, while in others, they may confer a survival advantage. Mutations are the driving force behind evolution, as they introduce new genetic variability into populations, which can then be acted upon by natural selection.

Ferredoxin-NADP Reductase (FDNR) is an enzyme that catalyzes the electron transfer from ferredoxin to NADP+, reducing it to NADPH. This reaction plays a crucial role in several metabolic pathways, including photosynthesis and nitrogen fixation.

In photosynthesis, FDNR is located in the stroma of chloroplasts and receives electrons from ferredoxin, which is reduced by photosystem I. The enzyme then transfers these electrons to NADP+, generating NADPH, which is used in the Calvin cycle for carbon fixation.

In nitrogen fixation, FDNR is found in the nitrogen-fixing bacteria and receives electrons from ferredoxin, which is reduced by nitrogenase. The enzyme then transfers these electrons to NADP+, generating NADPH, which is used in the reduction of nitrogen gas (N2) to ammonia (NH3).

FDNR is a flavoprotein that contains a FAD cofactor and an iron-sulfur cluster. The enzyme catalyzes the electron transfer through a series of conformational changes that bring ferredoxin and NADP+ in close proximity, allowing for efficient electron transfer.

Allosteric regulation is a process that describes the way in which the binding of a molecule (known as a ligand) to an enzyme or protein at one site affects the ability of another molecule to bind to a different site on the same enzyme or protein. This interaction can either enhance (positive allosteric regulation) or inhibit (negative allosteric regulation) the activity of the enzyme or protein, depending on the nature of the ligand and its effect on the shape and/or conformation of the enzyme or protein.

In an allosteric regulatory system, the binding of the first molecule to the enzyme or protein causes a conformational change in the protein structure that alters the affinity of the second site for its ligand. This can result in changes in the activity of the enzyme or protein, allowing for fine-tuning of biochemical pathways and regulatory processes within cells.

Allosteric regulation is a fundamental mechanism in many biological systems, including metabolic pathways, signal transduction cascades, and gene expression networks. Understanding allosteric regulation can provide valuable insights into the mechanisms underlying various physiological and pathological processes, and can inform the development of novel therapeutic strategies for the treatment of disease.

Nucleotides are the basic structural units of nucleic acids, such as DNA and RNA. They consist of a nitrogenous base (adenine, guanine, cytosine, thymine or uracil), a pentose sugar (ribose in RNA and deoxyribose in DNA) and one to three phosphate groups. Nucleotides are linked together by phosphodiester bonds between the sugar of one nucleotide and the phosphate group of another, forming long chains known as polynucleotides. The sequence of these nucleotides determines the genetic information carried in DNA and RNA, which is essential for the functioning, reproduction and survival of all living organisms.

Tyrosine is an non-essential amino acid, which means that it can be synthesized by the human body from another amino acid called phenylalanine. Its name is derived from the Greek word "tyros," which means cheese, as it was first isolated from casein, a protein found in cheese.

Tyrosine plays a crucial role in the production of several important substances in the body, including neurotransmitters such as dopamine, norepinephrine, and epinephrine, which are involved in various physiological processes, including mood regulation, stress response, and cognitive functions. It also serves as a precursor to melanin, the pigment responsible for skin, hair, and eye color.

In addition, tyrosine is involved in the structure of proteins and is essential for normal growth and development. Some individuals may require tyrosine supplementation if they have a genetic disorder that affects tyrosine metabolism or if they are phenylketonurics (PKU), who cannot metabolize phenylalanine, which can lead to elevated tyrosine levels in the blood. However, it is important to consult with a healthcare professional before starting any supplementation regimen.

Cytochrome reductases are a group of enzymes that play a crucial role in the electron transport chain, a process that occurs in the mitochondria of cells and is responsible for generating energy in the form of ATP (adenosine triphosphate). Specifically, cytochrome reductases are responsible for transferring electrons from one component of the electron transport chain to another, specifically to cytochromes.

There are several types of cytochrome reductases, including NADH dehydrogenase (also known as Complex I), succinate dehydrogenase (also known as Complex II), and ubiquinone-cytochrome c reductase (also known as Complex III). These enzymes help to facilitate the flow of electrons through the electron transport chain, which is essential for the production of ATP and the maintenance of cellular homeostasis.

Defects in cytochrome reductases can lead to a variety of mitochondrial diseases, which can affect multiple organ systems and may be associated with symptoms such as muscle weakness, developmental delays, and cardiac dysfunction.

DNA replication is the biological process by which DNA makes an identical copy of itself during cell division. It is a fundamental mechanism that allows genetic information to be passed down from one generation of cells to the next. During DNA replication, each strand of the double helix serves as a template for the synthesis of a new complementary strand. This results in the creation of two identical DNA molecules. The enzymes responsible for DNA replication include helicase, which unwinds the double helix, and polymerase, which adds nucleotides to the growing strands.

Substrate specificity in the context of medical biochemistry and enzymology refers to the ability of an enzyme to selectively bind and catalyze a chemical reaction with a particular substrate (or a group of similar substrates) while discriminating against other molecules that are not substrates. This specificity arises from the three-dimensional structure of the enzyme, which has evolved to match the shape, charge distribution, and functional groups of its physiological substrate(s).

Substrate specificity is a fundamental property of enzymes that enables them to carry out highly selective chemical transformations in the complex cellular environment. The active site of an enzyme, where the catalysis takes place, has a unique conformation that complements the shape and charge distribution of its substrate(s). This ensures efficient recognition, binding, and conversion of the substrate into the desired product while minimizing unwanted side reactions with other molecules.

Substrate specificity can be categorized as:

1. Absolute specificity: An enzyme that can only act on a single substrate or a very narrow group of structurally related substrates, showing no activity towards any other molecule.
2. Group specificity: An enzyme that prefers to act on a particular functional group or class of compounds but can still accommodate minor structural variations within the substrate.
3. Broad or promiscuous specificity: An enzyme that can act on a wide range of structurally diverse substrates, albeit with varying catalytic efficiencies.

Understanding substrate specificity is crucial for elucidating enzymatic mechanisms, designing drugs that target specific enzymes or pathways, and developing biotechnological applications that rely on the controlled manipulation of enzyme activities.

Mössbauer spectroscopy is a nuclear solid-state physics technique that provides detailed information about the chemical environment and electronic structure of iron (Fe), tin (Sn), antimony (Sb), and other nuclei in a sample. This technique uses the Mössbauer effect, which is the recoil-free emission and absorption of gamma rays by atomic nuclei bound in a solid lattice.

In Mössbauer spectroscopy, a source emits gamma rays that are absorbed by atoms with the same nuclear species in the sample. The energy of the gamma rays can be shifted due to the interaction between the gamma rays and the atomic electrons, which is influenced by the chemical environment and electronic structure of the nuclei in the sample. By analyzing these shifts in energy, researchers can determine various properties of the sample, such as oxidation state, coordination number, and local symmetry around the absorbing nuclei.

Mössbauer spectroscopy is a valuable tool for studying materials with high resolution and sensitivity to subtle changes in their structure and composition. It has applications in fields such as chemistry, physics, biology, geology, and materials science.

Gallium is not a medical term, but it's a chemical element with the symbol Ga and atomic number 31. It is a soft, silvery-blue metal that melts at a temperature just above room temperature. In medicine, gallium compounds such as gallium nitrate and gallium citrate are used as radiopharmaceuticals for diagnostic purposes in nuclear medicine imaging studies, particularly in the detection of inflammation, infection, and some types of cancer.

For example, Gallium-67 is a radioactive isotope that can be injected into the body to produce images of various diseases such as abscesses, osteomyelitis (bone infection), and tumors using a gamma camera. The way gallium distributes in the body can provide valuable information about the presence and extent of disease.

Therefore, while gallium is not a medical term itself, it has important medical applications as a diagnostic tool in nuclear medicine.

Molecular cloning is a laboratory technique used to create multiple copies of a specific DNA sequence. This process involves several steps:

1. Isolation: The first step in molecular cloning is to isolate the DNA sequence of interest from the rest of the genomic DNA. This can be done using various methods such as PCR (polymerase chain reaction), restriction enzymes, or hybridization.
2. Vector construction: Once the DNA sequence of interest has been isolated, it must be inserted into a vector, which is a small circular DNA molecule that can replicate independently in a host cell. Common vectors used in molecular cloning include plasmids and phages.
3. Transformation: The constructed vector is then introduced into a host cell, usually a bacterial or yeast cell, through a process called transformation. This can be done using various methods such as electroporation or chemical transformation.
4. Selection: After transformation, the host cells are grown in selective media that allow only those cells containing the vector to grow. This ensures that the DNA sequence of interest has been successfully cloned into the vector.
5. Amplification: Once the host cells have been selected, they can be grown in large quantities to amplify the number of copies of the cloned DNA sequence.

Molecular cloning is a powerful tool in molecular biology and has numerous applications, including the production of recombinant proteins, gene therapy, functional analysis of genes, and genetic engineering.

Recombinant proteins are artificially created proteins produced through the use of recombinant DNA technology. This process involves combining DNA molecules from different sources to create a new set of genes that encode for a specific protein. The resulting recombinant protein can then be expressed, purified, and used for various applications in research, medicine, and industry.

Recombinant proteins are widely used in biomedical research to study protein function, structure, and interactions. They are also used in the development of diagnostic tests, vaccines, and therapeutic drugs. For example, recombinant insulin is a common treatment for diabetes, while recombinant human growth hormone is used to treat growth disorders.

The production of recombinant proteins typically involves the use of host cells, such as bacteria, yeast, or mammalian cells, which are engineered to express the desired protein. The host cells are transformed with a plasmid vector containing the gene of interest, along with regulatory elements that control its expression. Once the host cells are cultured and the protein is expressed, it can be purified using various chromatography techniques.

Overall, recombinant proteins have revolutionized many areas of biology and medicine, enabling researchers to study and manipulate proteins in ways that were previously impossible.

NADP (Nicotinamide Adenine Dinucleotide Phosphate) is a coenzyme that plays a crucial role as an electron carrier in various redox reactions in the human body. It exists in two forms: NADP+, which functions as an oxidizing agent and accepts electrons, and NADPH, which serves as a reducing agent and donates electrons.

NADPH is particularly important in anabolic processes, such as lipid and nucleotide synthesis, where it provides the necessary reducing equivalents to drive these reactions forward. It also plays a critical role in maintaining the cellular redox balance by participating in antioxidant defense mechanisms that neutralize harmful reactive oxygen species (ROS).

In addition, NADP is involved in various metabolic pathways, including the pentose phosphate pathway and the Calvin cycle in photosynthesis. Overall, NADP and its reduced form, NADPH, are essential molecules for maintaining proper cellular function and energy homeostasis.

Sequence homology, amino acid, refers to the similarity in the order of amino acids in a protein or a portion of a protein between two or more species. This similarity can be used to infer evolutionary relationships and functional similarities between proteins. The higher the degree of sequence homology, the more likely it is that the proteins are related and have similar functions. Sequence homology can be determined through various methods such as pairwise alignment or multiple sequence alignment, which compare the sequences and calculate a score based on the number and type of matching amino acids.

DCMP deaminase is an enzyme that catalyzes the deamination of deoxycytidine monophosphate (dCMP) to deoxyuridine monophosphate (dUMP). This reaction is a part of the pyrimidine nucleotide biosynthesis pathway. The enzyme's systematic name is "deoxycytidine monophosphate deaminase." It plays a crucial role in DNA synthesis and maintenance by providing the necessary precursor (dUMP) for thymidylate synthesis, which is essential for the production of thymidine triphosphate (dTTP), one of the four building blocks of DNA.

Anaerobiosis is a state in which an organism or a portion of an organism is able to live and grow in the absence of molecular oxygen (O2). In biological contexts, "anaerobe" refers to any organism that does not require oxygen for growth, and "aerobe" refers to an organism that does require oxygen for growth.

There are two types of anaerobes: obligate anaerobes, which cannot tolerate the presence of oxygen and will die if exposed to it; and facultative anaerobes, which can grow with or without oxygen but prefer to grow in its absence. Some organisms are able to switch between aerobic and anaerobic metabolism depending on the availability of oxygen, a process known as "facultative anaerobiosis."

Anaerobic respiration is a type of metabolic process that occurs in the absence of molecular oxygen. In this process, organisms use alternative electron acceptors other than oxygen to generate energy through the transfer of electrons during cellular respiration. Examples of alternative electron acceptors include nitrate, sulfate, and carbon dioxide.

Anaerobic metabolism is less efficient than aerobic metabolism in terms of energy production, but it allows organisms to survive in environments where oxygen is not available or is toxic. Anaerobic bacteria are important decomposers in many ecosystems, breaking down organic matter and releasing nutrients back into the environment. In the human body, anaerobic bacteria can cause infections and other health problems if they proliferate in areas with low oxygen levels, such as the mouth, intestines, or deep tissue wounds.

Macromolecular substances, also known as macromolecules, are large, complex molecules made up of repeating subunits called monomers. These substances are formed through polymerization, a process in which many small molecules combine to form a larger one. Macromolecular substances can be naturally occurring, such as proteins, DNA, and carbohydrates, or synthetic, such as plastics and synthetic fibers.

In the context of medicine, macromolecular substances are often used in the development of drugs and medical devices. For example, some drugs are designed to bind to specific macromolecules in the body, such as proteins or DNA, in order to alter their function and produce a therapeutic effect. Additionally, macromolecular substances may be used in the creation of medical implants, such as artificial joints and heart valves, due to their strength and durability.

It is important for healthcare professionals to have an understanding of macromolecular substances and how they function in the body, as this knowledge can inform the development and use of medical treatments.

Manganese is not a medical condition, but it's an essential trace element that is vital for human health. Here is the medical definition of Manganese:

Manganese (Mn) is a trace mineral that is present in tiny amounts in the body. It is found mainly in bones, the liver, kidneys, and pancreas. Manganese helps the body form connective tissue, bones, blood clotting factors, and sex hormones. It also plays a role in fat and carbohydrate metabolism, calcium absorption, and blood sugar regulation. Manganese is also necessary for normal brain and nerve function.

The recommended dietary allowance (RDA) for manganese is 2.3 mg per day for adult men and 1.8 mg per day for adult women. Good food sources of manganese include nuts, seeds, legumes, whole grains, green leafy vegetables, and tea.

In some cases, exposure to high levels of manganese can cause neurological symptoms similar to Parkinson's disease, a condition known as manganism. However, this is rare and usually occurs in people who are occupationally exposed to manganese dust or fumes, such as welders.

Bacterial proteins are a type of protein that are produced by bacteria as part of their structural or functional components. These proteins can be involved in various cellular processes, such as metabolism, DNA replication, transcription, and translation. They can also play a role in bacterial pathogenesis, helping the bacteria to evade the host's immune system, acquire nutrients, and multiply within the host.

Bacterial proteins can be classified into different categories based on their function, such as:

1. Enzymes: Proteins that catalyze chemical reactions in the bacterial cell.
2. Structural proteins: Proteins that provide structural support and maintain the shape of the bacterial cell.
3. Signaling proteins: Proteins that help bacteria to communicate with each other and coordinate their behavior.
4. Transport proteins: Proteins that facilitate the movement of molecules across the bacterial cell membrane.
5. Toxins: Proteins that are produced by pathogenic bacteria to damage host cells and promote infection.
6. Surface proteins: Proteins that are located on the surface of the bacterial cell and interact with the environment or host cells.

Understanding the structure and function of bacterial proteins is important for developing new antibiotics, vaccines, and other therapeutic strategies to combat bacterial infections.

Uridine diphosphate (UDP) is a nucleotide diphosphate that consists of a pyrophosphate group, a ribose sugar, and the nucleobase uracil. It plays a crucial role as a coenzyme in various biosynthetic reactions, including the synthesis of glycogen, proteoglycans, and other polysaccharides. UDP is also involved in the detoxification of bilirubin, an end product of hemoglobin breakdown, by converting it to a water-soluble form that can be excreted through the bile. Additionally, UDP serves as a precursor for the synthesis of other nucleotides and their derivatives.

An allosteric site is a distinct and separate binding site on a protein (usually an enzyme) other than the active site where the substrate binds. The binding of a molecule (known as an allosteric modulator or effector) to this site can cause a conformational change in the protein's structure, which in turn affects its activity, either by enhancing (allosteric activation) or inhibiting (allosteric inhibition) its function. This allosteric regulation allows for complex control mechanisms in biological systems and is crucial for many cellular processes.

Molecular models are three-dimensional representations of molecular structures that are used in the field of molecular biology and chemistry to visualize and understand the spatial arrangement of atoms and bonds within a molecule. These models can be physical or computer-generated and allow researchers to study the shape, size, and behavior of molecules, which is crucial for understanding their function and interactions with other molecules.

Physical molecular models are often made up of balls (representing atoms) connected by rods or sticks (representing bonds). These models can be constructed manually using materials such as plastic or wooden balls and rods, or they can be created using 3D printing technology.

Computer-generated molecular models, on the other hand, are created using specialized software that allows researchers to visualize and manipulate molecular structures in three dimensions. These models can be used to simulate molecular interactions, predict molecular behavior, and design new drugs or chemicals with specific properties. Overall, molecular models play a critical role in advancing our understanding of molecular structures and their functions.

DNA damage refers to any alteration in the structure or composition of deoxyribonucleic acid (DNA), which is the genetic material present in cells. DNA damage can result from various internal and external factors, including environmental exposures such as ultraviolet radiation, tobacco smoke, and certain chemicals, as well as normal cellular processes such as replication and oxidative metabolism.

Examples of DNA damage include base modifications, base deletions or insertions, single-strand breaks, double-strand breaks, and crosslinks between the two strands of the DNA helix. These types of damage can lead to mutations, genomic instability, and chromosomal aberrations, which can contribute to the development of diseases such as cancer, neurodegenerative disorders, and aging-related conditions.

The body has several mechanisms for repairing DNA damage, including base excision repair, nucleotide excision repair, mismatch repair, and double-strand break repair. However, if the damage is too extensive or the repair mechanisms are impaired, the cell may undergo apoptosis (programmed cell death) to prevent the propagation of potentially harmful mutations.

Catalysis is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst, which remains unchanged at the end of the reaction. A catalyst lowers the activation energy required for the reaction to occur, thereby allowing the reaction to proceed more quickly and efficiently. This can be particularly important in biological systems, where enzymes act as catalysts to speed up metabolic reactions that are essential for life.

Ferrous compounds are inorganic substances that contain iron (Fe) in its +2 oxidation state. The term "ferrous" is derived from the Latin word "ferrum," which means iron. Ferrous compounds are often used in medicine, particularly in the treatment of iron-deficiency anemia due to their ability to provide bioavailable iron to the body.

Examples of ferrous compounds include ferrous sulfate, ferrous gluconate, and ferrous fumarate. These compounds are commonly found in dietary supplements and multivitamins. Ferrous sulfate is one of the most commonly used forms of iron supplementation, as it has a high iron content and is relatively inexpensive.

It's important to note that ferrous compounds can be toxic in large doses, so they should be taken under the guidance of a healthcare professional. Overdose can lead to symptoms such as nausea, vomiting, diarrhea, abdominal pain, and potentially fatal consequences if left untreated.

Deoxycytidine kinase (dCK) is an enzyme that plays a crucial role in the phosphorylation of deoxycytidine and its analogs, which are important components in the intracellular metabolism of DNA precursors. The enzyme catalyzes the transfer of a phosphate group from adenosine triphosphate (ATP) to the hydroxyl group at the 5' carbon atom of deoxycytidine, forming deoxycytidine monophosphate (dCMP).

Deoxycytidine kinase is a key enzyme in the salvage pathway of pyrimidine nucleotide synthesis and is also involved in the activation of many antiviral and anticancer drugs that are analogs of deoxycytidine. The activity of dCK is tightly regulated, and its expression levels can vary depending on the cell type and physiological conditions.

In addition to its role in nucleotide metabolism, dCK has been implicated in various biological processes, including DNA damage response, cell cycle regulation, and apoptosis. Abnormalities in dCK activity or expression have been associated with several human diseases, including cancer and viral infections. Therefore, modulation of dCK activity has emerged as a potential therapeutic strategy for the treatment of these conditions.

Tetrahydrofolate dehydrogenase (EC 1.5.1.20) is an enzyme involved in folate metabolism. The enzyme catalyzes the oxidation of tetrahydrofolate (THF) to dihydrofolate (DHF), while simultaneously reducing NADP+ to NADPH.

The reaction can be summarized as follows:

THF + NADP+ -> DHF + NADPH + H+

This enzyme plays a crucial role in the synthesis of purines and thymidylate, which are essential components of DNA and RNA. Therefore, any defects or deficiencies in tetrahydrofolate dehydrogenase can lead to various medical conditions, including megaloblastic anemia and neural tube defects during fetal development.

NADH, NADPH oxidoreductases are a class of enzymes that catalyze the redox reaction between NADH or NADPH and various electron acceptors. These enzymes play a crucial role in cellular metabolism by transferring electrons from NADH or NADPH to other molecules, which is essential for many biochemical reactions.

NADH (nicotinamide adenine dinucleotide hydrogen) and NADPH (nicotinamide adenine dinucleotide phosphate hydrogen) are coenzymes that act as electron carriers in redox reactions. They consist of a nicotinamide ring, which undergoes reduction or oxidation by accepting or donating electrons and a proton (H+).

NADH, NADPH oxidoreductases are classified based on their structure and mechanism of action. Some examples include:

1. Dehydrogenases: These enzymes catalyze the oxidation of NADH or NADPH to NAD+ or NADP+ while reducing an organic substrate. Examples include lactate dehydrogenase, alcohol dehydrogenase, and malate dehydrogenase.
2. Oxidases: These enzymes catalyze the oxidation of NADH or NADPH to NAD+ or NADP+ while reducing molecular oxygen (O2) to water (H2O). Examples include NADH oxidase and NADPH oxidase.
3. Reductases: These enzymes catalyze the reduction of various electron acceptors using NADH or NADPH as a source of electrons. Examples include glutathione reductase, thioredoxin reductase, and nitrate reductase.

Overall, NADH, NADPH oxidoreductases are essential for maintaining the redox balance in cells and play a critical role in various metabolic pathways, including energy production, detoxification, and biosynthesis.

A cell line is a culture of cells that are grown in a laboratory for use in research. These cells are usually taken from a single cell or group of cells, and they are able to divide and grow continuously in the lab. Cell lines can come from many different sources, including animals, plants, and humans. They are often used in scientific research to study cellular processes, disease mechanisms, and to test new drugs or treatments. Some common types of human cell lines include HeLa cells (which come from a cancer patient named Henrietta Lacks), HEK293 cells (which come from embryonic kidney cells), and HUVEC cells (which come from umbilical vein endothelial cells). It is important to note that cell lines are not the same as primary cells, which are cells that are taken directly from a living organism and have not been grown in the lab.

Deoxycytidine is a chemical compound that is a component of DNA, one of the nucleic acids in living organisms. It is a nucleoside, consisting of the sugar deoxyribose and the base cytosine. Deoxycytidine pairs with guanine via hydrogen bonds to form base pairs in the double helix structure of DNA.

In biochemistry, deoxycytidine can also exist as a free nucleoside, not bound to other molecules. It is involved in various cellular processes related to DNA metabolism and replication. Deoxycytidine can be phosphorylated to form deoxycytidine monophosphate (dCMP), which is an important intermediate in the synthesis of DNA.

It's worth noting that while deoxycytidine is a component of DNA, its counterpart in RNA is cytidine, which contains ribose instead of deoxyribose as the sugar component.

Bacteriophage T4, also known as T4 phage, is a type of virus that infects and replicates within the bacterium Escherichia coli (E. coli). It is one of the most well-studied bacteriophages and has been used as a model organism in molecular biology research for many decades.

T4 phage has a complex structure, with an icosahedral head that contains its genetic material (DNA) and a tail that attaches to the host cell and injects the DNA inside. The T4 phage genome is around 169 kilobases in length and encodes approximately 289 proteins.

Once inside the host cell, the T4 phage DNA takes over the bacterial machinery to produce new viral particles. The host cell eventually lyses (bursts), releasing hundreds of new phages into the environment. T4 phage is a lytic phage, meaning that it only replicates through the lytic cycle and does not integrate its genome into the host's chromosome.

T4 phage has been used in various applications, including bacterial typing, phage therapy, and genetic engineering. Its study has contributed significantly to our understanding of molecular biology, genetics, and virology.

Deoxyuracil nucleotides are chemical compounds that are the building blocks of DNA. Specifically, they are the form of nucleotides that contain the sugar deoxyribose and the nucleobase deoxyuracil. In DNA, deoxyuracil nucleotides pair with deoxyadenosine nucleotides through base pairing.

Deoxyuracil is a nucleobase that is similar to thymine, but it lacks a methyl group. Thymine is the usual nucleobase that pairs with adenine in DNA, while uracil is typically found in RNA paired with adenine. However, in certain circumstances, such as during DNA repair or damage, deoxyuracil can be incorporated into DNA instead of thymine.

Deoxyuracil nucleotides are important for understanding DNA replication, repair, and mutation. Abnormalities in the incorporation or removal of deoxyuracil nucleotides can lead to genetic disorders, cancer, and other diseases.

Cytidine triphosphate (CTP) is a nucleotide that plays a crucial role in the synthesis of RNA. It consists of a cytosine base, a ribose sugar, and three phosphate groups. Cytidine triphosphate is one of the four main building blocks of RNA, along with adenosine triphosphate (ATP), guanosine triphosphate (GTP), and uridine triphosphate (UTP). These nucleotides are essential for various cellular processes, including energy transfer, signal transduction, and biosynthesis. CTP is also involved in the regulation of several metabolic pathways and serves as a cofactor for enzymes that catalyze biochemical reactions. Like other triphosphate nucleotides, CTP provides energy for cellular functions by donating its phosphate groups in energy-consuming processes.

In the context of medical and biological sciences, a "binding site" refers to a specific location on a protein, molecule, or cell where another molecule can attach or bind. This binding interaction can lead to various functional changes in the original protein or molecule. The other molecule that binds to the binding site is often referred to as a ligand, which can be a small molecule, ion, or even another protein.

The binding between a ligand and its target binding site can be specific and selective, meaning that only certain ligands can bind to particular binding sites with high affinity. This specificity plays a crucial role in various biological processes, such as signal transduction, enzyme catalysis, or drug action.

In the case of drug development, understanding the location and properties of binding sites on target proteins is essential for designing drugs that can selectively bind to these sites and modulate protein function. This knowledge can help create more effective and safer therapeutic options for various diseases.

A catalytic domain is a portion or region within a protein that contains the active site, where the chemical reactions necessary for the protein's function are carried out. This domain is responsible for the catalysis of biological reactions, hence the name "catalytic domain." The catalytic domain is often composed of specific amino acid residues that come together to form the active site, creating a unique three-dimensional structure that enables the protein to perform its specific function.

In enzymes, for example, the catalytic domain contains the residues that bind and convert substrates into products through chemical reactions. In receptors, the catalytic domain may be involved in signal transduction or other regulatory functions. Understanding the structure and function of catalytic domains is crucial to understanding the mechanisms of protein function and can provide valuable insights for drug design and therapeutic interventions.

Iron chelating agents are medications that bind to iron in the body, forming a stable complex that can then be excreted from the body. These agents are primarily used to treat iron overload, a condition that can occur due to frequent blood transfusions or certain genetic disorders such as hemochromatosis. By reducing the amount of iron in the body, these medications can help prevent or reduce damage to organs such as the heart and liver. Examples of iron chelating agents include deferoxamine, deferasirox, and deferiprone.

Gene expression regulation, enzymologic refers to the biochemical processes and mechanisms that control the transcription and translation of specific genes into functional proteins or enzymes. This regulation is achieved through various enzymatic activities that can either activate or repress gene expression at different levels, such as chromatin remodeling, transcription factor activation, mRNA processing, and protein degradation.

Enzymologic regulation of gene expression involves the action of specific enzymes that catalyze chemical reactions involved in these processes. For example, histone-modifying enzymes can alter the structure of chromatin to make genes more or less accessible for transcription, while RNA polymerase and its associated factors are responsible for transcribing DNA into mRNA. Additionally, various enzymes are involved in post-transcriptional modifications of mRNA, such as splicing, capping, and tailing, which can affect the stability and translation of the transcript.

Overall, the enzymologic regulation of gene expression is a complex and dynamic process that allows cells to respond to changes in their environment and maintain proper physiological function.

The cell cycle is a series of events that take place in a cell leading to its division and duplication. It consists of four main phases: G1 phase, S phase, G2 phase, and M phase.

During the G1 phase, the cell grows in size and synthesizes mRNA and proteins in preparation for DNA replication. In the S phase, the cell's DNA is copied, resulting in two complete sets of chromosomes. During the G2 phase, the cell continues to grow and produces more proteins and organelles necessary for cell division.

The M phase is the final stage of the cell cycle and consists of mitosis (nuclear division) and cytokinesis (cytoplasmic division). Mitosis results in two genetically identical daughter nuclei, while cytokinesis divides the cytoplasm and creates two separate daughter cells.

The cell cycle is regulated by various checkpoints that ensure the proper completion of each phase before progressing to the next. These checkpoints help prevent errors in DNA replication and division, which can lead to mutations and cancer.

I'm sorry for any confusion, but "Carcinoma, Ehrlich Tumor" is not a recognized medical term or a valid medical definition. The term "Ehrlich tumor" is sometimes used to refer to a type of transplantable tumor that was first developed by the German physician Paul Ehrlich in the early 20th century for cancer research purposes. However, it's important to note that this type of tumor is not a naturally occurring cancer and is typically used only in laboratory experiments.

Carcinoma, on the other hand, is a medical term that refers to a type of cancer that starts in cells that line the inner or outer surfaces of organs. Carcinomas can develop in various parts of the body, including the lungs, breasts, colon, and skin.

If you have any specific questions about cancer or a particular medical condition, I would be happy to try to help answer them for you.

Arabinonucleosides are glycosylamines derived from arabinose, a monosaccharide (simple sugar) that is a component of certain complex carbohydrates. In an arabinonucleoside, the arabinose molecule is linked to a nitrogenous base, such as adenine, guanine, cytosine, uracil, or thymine, through a glycosidic bond. These types of compounds are not typically found in nature but can be synthesized in the laboratory for research purposes. They may have potential applications in the development of new drugs, particularly in the area of antiviral and anticancer therapy.

Leukemia L1210 is not a medical definition itself, but it refers to a specific mouse leukemia cell line that was established in 1948. These cells are a type of acute myeloid leukemia (AML) and have been widely used in cancer research as a model for studying the disease, testing new therapies, and understanding the biology of leukemia. The L1210 cell line has contributed significantly to the development of various chemotherapeutic agents and treatment strategies for leukemia and other cancers.

Deoxyribonucleic acid (DNA) is the genetic material present in the cells of organisms where it is responsible for the storage and transmission of hereditary information. DNA is a long molecule that consists of two strands coiled together to form a double helix. Each strand is made up of a series of four nucleotide bases - adenine (A), guanine (G), cytosine (C), and thymine (T) - that are linked together by phosphate and sugar groups. The sequence of these bases along the length of the molecule encodes genetic information, with A always pairing with T and C always pairing with G. This base-pairing allows for the replication and transcription of DNA, which are essential processes in the functioning and reproduction of all living organisms.

"Cellophane" is not a medical term. It is a type of thin, transparent sheet material made from regenerated cellulose, which is often used for packaging or wrapping purposes in various industries including food and medical. However, it does not have a specific medical definition.

Phosphoribosylaminoimidazolecarboxamide formyltransferase (AIRFT) is an enzyme involved in the purine nucleotide biosynthesis pathway. The systematic medical name for this enzyme is "phosphoribosylaminoimidazole carboxamide formyltransferase, IMP cyclohydrolase, and GMP synthase."

The primary function of AIRFT is to catalyze the conversion of 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR) to formylated AICAR (FAICAR), which is an essential step in the synthesis of inosine monophosphate (IMP). IMP is a key precursor for the biosynthesis of both adenine and guanine nucleotides.

The enzyme's activity can be measured by determining the rate of conversion of AICAR to FAICAR, which requires the presence of 10-formyltetrahydrofolate (10-Formyl-THF) as a cofactor. Deficiency in this enzyme can lead to impaired purine synthesis and may result in various clinical manifestations such as developmental delay, neurological symptoms, and immunodeficiency.

Asthenia is a medical term that refers to a condition of unusual physical weakness or exhaustion that is not relieved by rest. It can be a symptom of various underlying health issues, such as infections, neurological disorders, endocrine diseases, and mental health conditions. Asthenia should not be confused with general fatigue or tiredness, as it is more severe, persistent, and debilitating.

The term "asthenia" comes from the Greek words "a" (without) and "sthenos" (strength), which together mean "without strength." In medical contexts, asthenia is often used to describe a significant decrease in muscle strength or energy levels that interferes with daily activities and reduces the overall quality of life.

Asthenia can manifest as a general feeling of weakness, fatigue, lethargy, or lack of stamina. In some cases, it may be accompanied by other symptoms such as dizziness, lightheadedness, headaches, irritability, and depression. Depending on the underlying cause, asthenia may be treated with various interventions, including medication, lifestyle changes, physical therapy, or counseling.

X-ray crystallography is a technique used in structural biology to determine the three-dimensional arrangement of atoms in a crystal lattice. In this method, a beam of X-rays is directed at a crystal and diffracts, or spreads out, into a pattern of spots called reflections. The intensity and angle of each reflection are measured and used to create an electron density map, which reveals the position and type of atoms in the crystal. This information can be used to determine the molecular structure of a compound, including its shape, size, and chemical bonds. X-ray crystallography is a powerful tool for understanding the structure and function of biological macromolecules such as proteins and nucleic acids.

"Saccharomyces cerevisiae" is not typically considered a medical term, but it is a scientific name used in the field of microbiology. It refers to a species of yeast that is commonly used in various industrial processes, such as baking and brewing. It's also widely used in scientific research due to its genetic tractability and eukaryotic cellular organization.

However, it does have some relevance to medical fields like medicine and nutrition. For example, certain strains of S. cerevisiae are used as probiotics, which can provide health benefits when consumed. They may help support gut health, enhance the immune system, and even assist in the digestion of certain nutrients.

In summary, "Saccharomyces cerevisiae" is a species of yeast with various industrial and potential medical applications.

Spectrophotometry is a technical analytical method used in the field of medicine and science to measure the amount of light absorbed or transmitted by a substance at specific wavelengths. This technique involves the use of a spectrophotometer, an instrument that measures the intensity of light as it passes through a sample.

In medical applications, spectrophotometry is often used in laboratory settings to analyze various biological samples such as blood, urine, and tissues. For example, it can be used to measure the concentration of specific chemicals or compounds in a sample by measuring the amount of light that is absorbed or transmitted at specific wavelengths.

In addition, spectrophotometry can also be used to assess the properties of biological tissues, such as their optical density and thickness. This information can be useful in the diagnosis and treatment of various medical conditions, including skin disorders, eye diseases, and cancer.

Overall, spectrophotometry is a valuable tool for medical professionals and researchers seeking to understand the composition and properties of various biological samples and tissues.

Protein conformation refers to the specific three-dimensional shape that a protein molecule assumes due to the spatial arrangement of its constituent amino acid residues and their associated chemical groups. This complex structure is determined by several factors, including covalent bonds (disulfide bridges), hydrogen bonds, van der Waals forces, and ionic bonds, which help stabilize the protein's unique conformation.

Protein conformations can be broadly classified into two categories: primary, secondary, tertiary, and quaternary structures. The primary structure represents the linear sequence of amino acids in a polypeptide chain. The secondary structure arises from local interactions between adjacent amino acid residues, leading to the formation of recurring motifs such as α-helices and β-sheets. Tertiary structure refers to the overall three-dimensional folding pattern of a single polypeptide chain, while quaternary structure describes the spatial arrangement of multiple folded polypeptide chains (subunits) that interact to form a functional protein complex.

Understanding protein conformation is crucial for elucidating protein function, as the specific three-dimensional shape of a protein directly influences its ability to interact with other molecules, such as ligands, nucleic acids, or other proteins. Any alterations in protein conformation due to genetic mutations, environmental factors, or chemical modifications can lead to loss of function, misfolding, aggregation, and disease states like neurodegenerative disorders and cancer.

Cytidine is a nucleoside, which consists of the sugar ribose and the nitrogenous base cytosine. It is an important component of RNA (ribonucleic acid), where it pairs with guanosine via hydrogen bonding to form a base pair. Cytidine can also be found in some DNA (deoxyribonucleic acid) sequences, particularly in viral DNA and in mitochondrial DNA.

Cytidine can be phosphorylated to form cytidine monophosphate (CMP), which is a nucleotide that plays a role in various biochemical reactions in the body. CMP can be further phosphorylated to form cytidine diphosphate (CDP) and cytidine triphosphate (CTP), which are involved in the synthesis of lipids, glycogen, and other molecules.

Cytidine is also available as a dietary supplement and has been studied for its potential benefits in treating various health conditions, such as liver disease and cancer. However, more research is needed to confirm these potential benefits and establish safe and effective dosages.

Coenzymes are small organic molecules that assist enzymes in catalyzing chemical reactions within cells. They typically act as carriers of specific atoms or groups of atoms during enzymatic reactions, facilitating the conversion of substrates into products. Coenzymes often bind temporarily to enzymes at the active site, forming an enzyme-coenzyme complex.

Coenzymes are usually derived from vitamins or minerals and are essential for maintaining proper metabolic functions in the body. Examples of coenzymes include nicotinamide adenine dinucleotide (NAD+), flavin adenine dinucleotide (FAD), and coenzyme A (CoA). When a coenzyme is used up in a reaction, it must be regenerated or replaced for the enzyme to continue functioning.

In summary, coenzymes are vital organic compounds that work closely with enzymes to facilitate biochemical reactions, ensuring the smooth operation of various metabolic processes within living organisms.

I'm sorry for any confusion, but "KB cells" is not a widely recognized or established term in medical or scientific communities. It's possible that "KB cells" may refer to a specific cell line used in scientific research. KB cells are a type of cell line derived from a human carcinoma (a type of cancer) of the nasopharynx (the upper part of the throat behind the nose). They are often used in studies related to cancer, virology, and other areas of biomedical research.

However, without more context or information, it's difficult to provide a more precise definition of "KB cells." If you have more information about where you encountered this term or what specific context it was used in, I may be able to give a more accurate answer.

Cell cycle proteins are a group of regulatory proteins that control the progression of the cell cycle, which is the series of events that take place in a eukaryotic cell leading to its division and duplication. These proteins can be classified into several categories based on their functions during different stages of the cell cycle.

The major groups of cell cycle proteins include:

1. Cyclin-dependent kinases (CDKs): CDKs are serine/threonine protein kinases that regulate key transitions in the cell cycle. They require binding to a regulatory subunit called cyclin to become active. Different CDK-cyclin complexes are activated at different stages of the cell cycle.
2. Cyclins: Cyclins are a family of regulatory proteins that bind and activate CDKs. Their levels fluctuate throughout the cell cycle, with specific cyclins expressed during particular phases. For example, cyclin D is important for the G1 to S phase transition, while cyclin B is required for the G2 to M phase transition.
3. CDK inhibitors (CKIs): CKIs are regulatory proteins that bind to and inhibit CDKs, thereby preventing their activation. CKIs can be divided into two main families: the INK4 family and the Cip/Kip family. INK4 family members specifically inhibit CDK4 and CDK6, while Cip/Kip family members inhibit a broader range of CDKs.
4. Anaphase-promoting complex/cyclosome (APC/C): APC/C is an E3 ubiquitin ligase that targets specific proteins for degradation by the 26S proteasome. During the cell cycle, APC/C regulates the metaphase to anaphase transition and the exit from mitosis by targeting securin and cyclin B for degradation.
5. Other regulatory proteins: Several other proteins play crucial roles in regulating the cell cycle, such as p53, a transcription factor that responds to DNA damage and arrests the cell cycle, and the polo-like kinases (PLKs), which are involved in various aspects of mitosis.

Overall, cell cycle proteins work together to ensure the proper progression of the cell cycle, maintain genomic stability, and prevent uncontrolled cell growth, which can lead to cancer.

Enzyme inhibitors are substances that bind to an enzyme and decrease its activity, preventing it from catalyzing a chemical reaction in the body. They can work by several mechanisms, including blocking the active site where the substrate binds, or binding to another site on the enzyme to change its shape and prevent substrate binding. Enzyme inhibitors are often used as drugs to treat various medical conditions, such as high blood pressure, abnormal heart rhythms, and bacterial infections. They can also be found naturally in some foods and plants, and can be used in research to understand enzyme function and regulation.

Methionine sulfoxide reductases (MSRs) are a group of enzymes that catalyze the reduction of methionine sulfoxides back to methionine in proteins. Methionine residues in proteins can be oxidized by reactive oxygen species (ROS) or other oxidizing agents, leading to the formation of methionine sulfoxide. This modification can affect protein function and stability. MSRs play a crucial role in protecting proteins from oxidative damage and maintaining their proper function.

There are two types of MSRs, designated as MSRA and MSRB. MSRA reduces methionine-S-sulfoxides, while MSRB reduces methionine-R-sulfoxides. Both enzymes require the cofactor thioredoxin to reduce the methionine sulfoxide back to methionine. The activity of MSRs is important in various biological processes, including protein folding, stress response, and aging. Defects in MSRs have been implicated in several diseases, such as Alzheimer's disease, Parkinson's disease, and cancer.

Protein binding, in the context of medical and biological sciences, refers to the interaction between a protein and another molecule (known as the ligand) that results in a stable complex. This process is often reversible and can be influenced by various factors such as pH, temperature, and concentration of the involved molecules.

In clinical chemistry, protein binding is particularly important when it comes to drugs, as many of them bind to proteins (especially albumin) in the bloodstream. The degree of protein binding can affect a drug's distribution, metabolism, and excretion, which in turn influence its therapeutic effectiveness and potential side effects.

Protein-bound drugs may be less available for interaction with their target tissues, as only the unbound or "free" fraction of the drug is active. Therefore, understanding protein binding can help optimize dosing regimens and minimize adverse reactions.

Messenger RNA (mRNA) is a type of RNA (ribonucleic acid) that carries genetic information copied from DNA in the form of a series of three-base code "words," each of which specifies a particular amino acid. This information is used by the cell's machinery to construct proteins, a process known as translation. After being transcribed from DNA, mRNA travels out of the nucleus to the ribosomes in the cytoplasm where protein synthesis occurs. Once the protein has been synthesized, the mRNA may be degraded and recycled. Post-transcriptional modifications can also occur to mRNA, such as alternative splicing and addition of a 5' cap and a poly(A) tail, which can affect its stability, localization, and translation efficiency.

Adenosine Triphosphate (ATP) is a high-energy molecule that stores and transports energy within cells. It is the main source of energy for most cellular processes, including muscle contraction, nerve impulse transmission, and protein synthesis. ATP is composed of a base (adenine), a sugar (ribose), and three phosphate groups. The bonds between these phosphate groups contain a significant amount of energy, which can be released when the bond between the second and third phosphate group is broken, resulting in the formation of adenosine diphosphate (ADP) and inorganic phosphate. This process is known as hydrolysis and can be catalyzed by various enzymes to drive a wide range of cellular functions. ATP can also be regenerated from ADP through various metabolic pathways, such as oxidative phosphorylation or substrate-level phosphorylation, allowing for the continuous supply of energy to cells.

Pyrimidine nucleotides are organic compounds that play crucial roles in various biological processes, particularly in the field of genetics and molecular biology. They are the building blocks of nucleic acids, which include DNA and RNA, and are essential for the storage, transmission, and expression of genetic information within cells.

Pyrimidine is a heterocyclic aromatic organic compound similar to benzene and pyridine, containing two nitrogen atoms at positions 1 and 3 of the six-member ring. Pyrimidine nucleotides are derivatives of pyrimidine, which contain a phosphate group, a pentose sugar (ribose or deoxyribose), and one of three pyrimidine bases: cytosine (C), thymine (T), or uracil (U).

* Cytosine is present in both DNA and RNA. It pairs with guanine via hydrogen bonding during DNA replication and transcription.
* Thymine is exclusively found in DNA, where it pairs with adenine through two hydrogen bonds.
* Uracil is a pyrimidine base that replaces thymine in RNA molecules and pairs with adenine via two hydrogen bonds during RNA transcription.

Pyrimidine nucleotides, along with purine nucleotides (adenine, guanine, and their derivatives), form the fundamental units of nucleic acids, contributing to the structure, function, and regulation of genetic material in living organisms.

Enzyme induction is a process by which the activity or expression of an enzyme is increased in response to some stimulus, such as a drug, hormone, or other environmental factor. This can occur through several mechanisms, including increasing the transcription of the enzyme's gene, stabilizing the mRNA that encodes the enzyme, or increasing the translation of the mRNA into protein.

In some cases, enzyme induction can be a beneficial process, such as when it helps the body to metabolize and clear drugs more quickly. However, in other cases, enzyme induction can have negative consequences, such as when it leads to the increased metabolism of important endogenous compounds or the activation of harmful procarcinogens.

Enzyme induction is an important concept in pharmacology and toxicology, as it can affect the efficacy and safety of drugs and other xenobiotics. It is also relevant to the study of drug interactions, as the induction of one enzyme by a drug can lead to altered metabolism and effects of another drug that is metabolized by the same enzyme.

Inosine is not a medical condition but a naturally occurring compound called a nucleoside, which is formed from the combination of hypoxanthine and ribose. It is an intermediate in the metabolic pathways of purine nucleotides, which are essential components of DNA and RNA. Inosine has been studied for its potential therapeutic benefits in various medical conditions, including neurodegenerative disorders, cardiovascular diseases, and cancer. However, more research is needed to fully understand its mechanisms and clinical applications.

Hydroxymethylglutaryl-CoA (HMG-CoA) reductase inhibitors, also known as statins, are a class of cholesterol-lowering medications. They work by inhibiting the enzyme HMG-CoA reductase, which plays a central role in the production of cholesterol in the liver. By blocking this enzyme, the liver is stimulated to take up more low-density lipoprotein (LDL) cholesterol from the bloodstream, leading to a decrease in LDL cholesterol levels and a reduced risk of cardiovascular disease.

Examples of HMG-CoA reductase inhibitors include atorvastatin, simvastatin, pravastatin, rosuvastatin, and fluvastatin. These medications are commonly prescribed to individuals with high cholesterol levels, particularly those who are at risk for or have established cardiovascular disease.

It's important to note that while HMG-CoA reductase inhibitors can be effective in reducing LDL cholesterol levels and the risk of cardiovascular events, they should be used as part of a comprehensive approach to managing high cholesterol, which may also include lifestyle modifications such as dietary changes, exercise, and weight management.

DNA primers are short single-stranded DNA molecules that serve as a starting point for DNA synthesis. They are typically used in laboratory techniques such as the polymerase chain reaction (PCR) and DNA sequencing. The primer binds to a complementary sequence on the DNA template through base pairing, providing a free 3'-hydroxyl group for the DNA polymerase enzyme to add nucleotides and synthesize a new strand of DNA. This allows for specific and targeted amplification or analysis of a particular region of interest within a larger DNA molecule.

Thermoplasma is a genus of archaea, which are single-celled microorganisms that lack a nucleus and other membrane-bound organelles. Thermoplasma species are extremophiles, meaning they thrive in extreme environments that are hostile to most other life forms. Specifically, Thermoplasma species are thermoacidophiles, which means they grow optimally at relatively high temperatures (45-60°C) and low pH levels (around 2).

Thermoplasma species have an unusual way of dealing with the harsh conditions of their environment. They lack a cell wall, which makes them highly resistant to heat and acidity. Instead, they have a unique outer membrane that is composed of proteins and lipids, which provides stability and protection in extreme environments.

Thermoplasma species are found in various habitats, including self-heating coal refuse piles, sulfur-rich hot springs, and solfataric fields. They have also been isolated from the acidic environments of industrial waste sites and even from the human mouth. Thermoplasma species are important in biotechnology due to their ability to produce enzymes that can function under extreme conditions, making them useful for various industrial applications.

Quinone reductases are a group of enzymes that catalyze the reduction of quinones to hydroquinones, using NADH or NADPH as an electron donor. This reaction is important in the detoxification of quinones, which are potentially toxic compounds produced during the metabolism of certain drugs, chemicals, and endogenous substances.

There are two main types of quinone reductases: NQO1 (NAD(P)H:quinone oxidoreductase 1) and NQO2 (NAD(P)H:quinone oxidoreductase 2). NQO1 is a cytosolic enzyme that can reduce a wide range of quinones, while NQO2 is a mitochondrial enzyme with a narrower substrate specificity.

Quinone reductases have been studied for their potential role in cancer prevention and treatment, as they may help to protect cells from oxidative stress and DNA damage caused by quinones and other toxic compounds. Additionally, some quinone reductase inhibitors have been developed as chemotherapeutic agents, as they can enhance the cytotoxicity of certain drugs that require quinone reduction for activation.

4-Nitroquinoline-1-oxide is a chemical compound that is often used in laboratory research as a carcinogenic agent. Its molecular formula is C6H4N2O3, and it is known to cause DNA damage and mutations, which can lead to the development of cancer. It is primarily used in scientific research to study the mechanisms of carcinogenesis and to test the effectiveness of potential cancer treatments.

It is important to note that 4-Nitroquinoline-1-oxide is not a medication or a treatment for any medical condition, and it should only be handled by trained professionals in a controlled laboratory setting.

Molecular weight, also known as molecular mass, is the mass of a molecule. It is expressed in units of atomic mass units (amu) or daltons (Da). Molecular weight is calculated by adding up the atomic weights of each atom in a molecule. It is a useful property in chemistry and biology, as it can be used to determine the concentration of a substance in a solution, or to calculate the amount of a substance that will react with another in a chemical reaction.

Deferoxamine is a medication used to treat iron overload, which can occur due to various reasons such as frequent blood transfusions or excessive iron intake. It works by binding to excess iron in the body and promoting its excretion through urine. This helps to prevent damage to organs such as the heart and liver that can be caused by high levels of iron.

Deferoxamine is an injectable medication that is typically administered intravenously or subcutaneously, depending on the specific regimen prescribed by a healthcare professional. It may also be used in combination with other medications to manage iron overload more effectively.

It's important to note that deferoxamine should only be used under the guidance of a medical professional, as improper use or dosing can lead to serious side effects or complications.

Site-directed mutagenesis is a molecular biology technique used to introduce specific and targeted changes to a specific DNA sequence. This process involves creating a new variant of a gene or a specific region of interest within a DNA molecule by introducing a planned, deliberate change, or mutation, at a predetermined site within the DNA sequence.

The methodology typically involves the use of molecular tools such as PCR (polymerase chain reaction), restriction enzymes, and/or ligases to introduce the desired mutation(s) into a plasmid or other vector containing the target DNA sequence. The resulting modified DNA molecule can then be used to transform host cells, allowing for the production of large quantities of the mutated gene or protein for further study.

Site-directed mutagenesis is a valuable tool in basic research, drug discovery, and biotechnology applications where specific changes to a DNA sequence are required to understand gene function, investigate protein structure/function relationships, or engineer novel biological properties into existing genes or proteins.

In genetics, sequence alignment is the process of arranging two or more DNA, RNA, or protein sequences to identify regions of similarity or homology between them. This is often done using computational methods to compare the nucleotide or amino acid sequences and identify matching patterns, which can provide insight into evolutionary relationships, functional domains, or potential genetic disorders. The alignment process typically involves adjusting gaps and mismatches in the sequences to maximize the similarity between them, resulting in an aligned sequence that can be visually represented and analyzed.

The Electron Transport Chain (ETC) is a series of complexes in the inner mitochondrial membrane that are involved in the process of cellular respiration. It is the final pathway for electrons derived from the oxidation of nutrients such as glucose, fatty acids, and amino acids to be transferred to molecular oxygen. This transfer of electrons drives the generation of a proton gradient across the inner mitochondrial membrane, which is then used by ATP synthase to produce ATP, the main energy currency of the cell.

The electron transport chain consists of four complexes (I-IV) and two mobile electron carriers (ubiquinone and cytochrome c). Electrons from NADH and FADH2 are transferred to Complex I and Complex II respectively, which then pass them along to ubiquinone. Ubiquinone then transfers the electrons to Complex III, which passes them on to cytochrome c. Finally, cytochrome c transfers the electrons to Complex IV, where they combine with oxygen and protons to form water.

The transfer of electrons through the ETC is accompanied by the pumping of protons from the mitochondrial matrix to the intermembrane space, creating a proton gradient. The flow of protons back across the inner membrane through ATP synthase drives the synthesis of ATP from ADP and inorganic phosphate.

Overall, the electron transport chain is a crucial process for generating energy in the form of ATP in the cell, and it plays a key role in many metabolic pathways.

Aerobiosis is the process of living, growing, and functioning in the presence of oxygen. It refers to the metabolic processes that require oxygen to break down nutrients and produce energy in cells. This is in contrast to anaerobiosis, which is the ability to live and grow in the absence of oxygen.

In medical terms, aerobiosis is often used to describe the growth of microorganisms, such as bacteria and fungi, that require oxygen to survive and multiply. These organisms are called aerobic organisms, and they play an important role in many biological processes, including decomposition and waste breakdown.

However, some microorganisms are unable to grow in the presence of oxygen and are instead restricted to environments where oxygen is absent or limited. These organisms are called anaerobic organisms, and their growth and metabolism are referred to as anaerobiosis.

Alcohol oxidoreductases are a class of enzymes that catalyze the oxidation of alcohols to aldehydes or ketones, while reducing nicotinamide adenine dinucleotide (NAD+) to NADH. These enzymes play an important role in the metabolism of alcohols and other organic compounds in living organisms.

The most well-known example of an alcohol oxidoreductase is alcohol dehydrogenase (ADH), which is responsible for the oxidation of ethanol to acetaldehyde in the liver during the metabolism of alcoholic beverages. Other examples include aldehyde dehydrogenases (ALDH) and sorbitol dehydrogenase (SDH).

These enzymes are important targets for the development of drugs used to treat alcohol use disorder, as inhibiting their activity can help to reduce the rate of ethanol metabolism and the severity of its effects on the body.

A bacterial gene is a segment of DNA (or RNA in some viruses) that contains the genetic information necessary for the synthesis of a functional bacterial protein or RNA molecule. These genes are responsible for encoding various characteristics and functions of bacteria such as metabolism, reproduction, and resistance to antibiotics. They can be transmitted between bacteria through horizontal gene transfer mechanisms like conjugation, transformation, and transduction. Bacterial genes are often organized into operons, which are clusters of genes that are transcribed together as a single mRNA molecule.

It's important to note that the term "bacterial gene" is used to describe genetic elements found in bacteria, but not all genetic elements in bacteria are considered genes. For example, some DNA sequences may not encode functional products and are therefore not considered genes. Additionally, some bacterial genes may be plasmid-borne or phage-borne, rather than being located on the bacterial chromosome.

Oxidoreductases acting on CH-CH group donors are a class of enzymes within the larger group of oxidoreductases, which are responsible for catalyzing oxidation-reduction reactions. Specifically, this subclass of enzymes acts upon donors containing a carbon-carbon (CH-CH) bond, where one atom or group of atoms is oxidized and another is reduced during the reaction process. These enzymes play crucial roles in various metabolic pathways, including the breakdown and synthesis of carbohydrates, lipids, and amino acids.

The reactions catalyzed by these enzymes involve the transfer of electrons and hydrogen atoms between the donor and an acceptor molecule. This process often results in the formation or cleavage of carbon-carbon bonds, making them essential for numerous biological processes. The systematic name for this class of enzymes is typically structured as "donor:acceptor oxidoreductase," where donor and acceptor represent the molecules involved in the electron transfer process.

Examples of enzymes that fall under this category include:

1. Aldehyde dehydrogenases (EC 1.2.1.3): These enzymes catalyze the oxidation of aldehydes to carboxylic acids, using NAD+ as an electron acceptor.
2. Dihydrodiol dehydrogenase (EC 1.3.1.14): This enzyme is responsible for the oxidation of dihydrodiols to catechols in the biodegradation of aromatic compounds.
3. Succinate dehydrogenase (EC 1.3.5.1): A key enzyme in the citric acid cycle, succinate dehydrogenase catalyzes the oxidation of succinate to fumarate and reduces FAD to FADH2.
4. Xylose reductase (EC 1.1.1.307): This enzyme is involved in the metabolism of pentoses, where it reduces xylose to xylitol using NADPH as a cofactor.

Nucleotide deaminases are a group of enzymes that catalyze the removal of an amino group (-NH2) from nucleotides, which are the building blocks of DNA and RNA. Specifically, these enzymes convert cytidine or adenosine to uridine or inosine, respectively, by removing an amino group from the corresponding nitrogenous base (cytosine or adenine).

There are several types of nucleotide deaminases that differ in their substrate specificity and cellular localization. For example, some enzymes deaminate DNA or RNA directly, while others act on free nucleotides or nucleosides. Nucleotide deaminases play important roles in various biological processes, including the regulation of gene expression, immune response, and DNA repair.

Abnormal activity or mutations in nucleotide deaminases have been associated with several human diseases, such as cancer, autoimmune disorders, and viral infections. Therefore, understanding the function and regulation of these enzymes is crucial for developing new therapeutic strategies to treat these conditions.

Ferric compounds are inorganic compounds that contain the iron(III) cation, Fe3+. Iron(III) is a transition metal and can form stable compounds with various anions. Ferric compounds are often colored due to the d-d transitions of the iron ion. Examples of ferric compounds include ferric chloride (FeCl3), ferric sulfate (Fe2(SO4)3), and ferric oxide (Fe2O3). Ferric compounds have a variety of uses, including as catalysts, in dye production, and in medical applications.

Dihydropteridine reductase is an enzyme that plays a crucial role in the metabolism of certain amino acids, specifically phenylalanine and tyrosine. This enzyme is responsible for reducing dihydropteridines to tetrahydropteridines, which is a necessary step in the regeneration of tetrahydrobiopterin (BH4), an essential cofactor for the enzymes phenylalanine hydroxylase and tyrosine hydroxylase.

Phenylalanine hydroxylase and tyrosine hydroxylase are involved in the conversion of the amino acids phenylalanine and tyrosine to tyrosine and dopa, respectively. Without sufficient BH4, these enzymes cannot function properly, leading to an accumulation of phenylalanine and a decrease in the levels of important neurotransmitters such as dopamine, norepinephrine, and serotonin.

Deficiency in dihydropteridine reductase can lead to a rare genetic disorder known as dihydropteridine reductase deficiency (DPRD), which is characterized by elevated levels of phenylalanine and neurotransmitter imbalances, resulting in neurological symptoms such as developmental delay, seizures, and hypotonia. Treatment typically involves a low-phenylalanine diet and supplementation with BH4.

Flavodoxin is not strictly a medical term, but it is a term used in biochemistry and molecular biology. Flavodoxins are small electron transfer proteins that contain a non-heme iron atom bound to a organic molecule called flavin mononucleotide (FMN). They play a role in various biological processes such as photosynthesis, nitrogen fixation and respiration where they function as electron carriers. Flavodoxins can undergo reversible oxidation and reduction, and this property allows them to transfer electrons between different enzymes during metabolic reactions. They are not specific to human physiology, but can be found in various organisms including bacteria, algae, and plants.

Corynebacterium is a genus of Gram-positive, rod-shaped bacteria that are commonly found on the skin and mucous membranes of humans and animals. Some species of Corynebacterium can cause disease in humans, including C. diphtheriae, which causes diphtheria, and C. jeikeium, which can cause various types of infections in immunocompromised individuals. Other species are part of the normal flora and are not typically pathogenic. The bacteria are characterized by their irregular, club-shaped appearance and their ability to form characteristic arrangements called palisades. They are facultative anaerobes, meaning they can grow in the presence or absence of oxygen.

'Escherichia coli (E. coli) proteins' refer to the various types of proteins that are produced and expressed by the bacterium Escherichia coli. These proteins play a critical role in the growth, development, and survival of the organism. They are involved in various cellular processes such as metabolism, DNA replication, transcription, translation, repair, and regulation.

E. coli is a gram-negative, facultative anaerobe that is commonly found in the intestines of warm-blooded organisms. It is widely used as a model organism in scientific research due to its well-studied genetics, rapid growth, and ability to be easily manipulated in the laboratory. As a result, many E. coli proteins have been identified, characterized, and studied in great detail.

Some examples of E. coli proteins include enzymes involved in carbohydrate metabolism such as lactase, sucrase, and maltose; proteins involved in DNA replication such as the polymerases, single-stranded binding proteins, and helicases; proteins involved in transcription such as RNA polymerase and sigma factors; proteins involved in translation such as ribosomal proteins, tRNAs, and aminoacyl-tRNA synthetases; and regulatory proteins such as global regulators, two-component systems, and transcription factors.

Understanding the structure, function, and regulation of E. coli proteins is essential for understanding the basic biology of this important organism, as well as for developing new strategies for combating bacterial infections and improving industrial processes involving bacteria.

Antimetabolites are a class of antineoplastic (chemotherapy) drugs that interfere with the metabolism of cancer cells and inhibit their growth and proliferation. These agents are structurally similar to naturally occurring metabolites, such as amino acids, nucleotides, and folic acid, which are essential for cellular replication and growth. Antimetabolites act as false analogs and get incorporated into the growing cells' DNA or RNA, causing disruption of the normal synthesis process, leading to cell cycle arrest and apoptosis (programmed cell death).

Examples of antimetabolite drugs include:

1. Folate antagonists: Methotrexate, Pemetrexed
2. Purine analogs: Mercaptopurine, Thioguanine, Fludarabine, Cladribine
3. Pyrimidine analogs: 5-Fluorouracil (5-FU), Capecitabine, Cytarabine, Gemcitabine

These drugs are used to treat various types of cancers, such as leukemias, lymphomas, breast, ovarian, and gastrointestinal cancers. Due to their mechanism of action, antimetabolites can also affect normal, rapidly dividing cells in the body, leading to side effects like myelosuppression (decreased production of blood cells), mucositis (inflammation and ulceration of the gastrointestinal tract), and alopecia (hair loss).

Drug resistance, also known as antimicrobial resistance, is the ability of a microorganism (such as bacteria, viruses, fungi, or parasites) to withstand the effects of a drug that was originally designed to inhibit or kill it. This occurs when the microorganism undergoes genetic changes that allow it to survive in the presence of the drug. As a result, the drug becomes less effective or even completely ineffective at treating infections caused by these resistant organisms.

Drug resistance can develop through various mechanisms, including mutations in the genes responsible for producing the target protein of the drug, alteration of the drug's target site, modification or destruction of the drug by enzymes produced by the microorganism, and active efflux of the drug from the cell.

The emergence and spread of drug-resistant microorganisms pose significant challenges in medical treatment, as they can lead to increased morbidity, mortality, and healthcare costs. The overuse and misuse of antimicrobial agents, as well as poor infection control practices, contribute to the development and dissemination of drug-resistant strains. To address this issue, it is crucial to promote prudent use of antimicrobials, enhance surveillance and monitoring of resistance patterns, invest in research and development of new antimicrobial agents, and strengthen infection prevention and control measures.

I'm sorry for any confusion, but "Pyridines" is not a medical term. It is a chemical term that refers to a class of organic compounds with the chemical structure of a six-membered ring containing one nitrogen atom and five carbon atoms (heterocyclic aromatic compound).

In a biological or medical context, pyridine derivatives can be found in various natural and synthetic substances. For example, some medications contain pyridine rings as part of their chemical structure. However, "Pyridines" itself is not a medical term or condition.

Thioredoxin Reductase 1 (TXNRD1) is an enzyme that belongs to the thioredoxin reductase family. It is a homodimeric flavoprotein that contains a selenocysteine residue at its active site, which is essential for its catalytic activity.

The primary function of TXNRD1 is to reduce and regenerate the oxidized form of thioredoxin (TXN) by using NADPH as an electron donor. Thioredoxin is a small protein that plays a crucial role in maintaining the redox balance within the cell by regulating various cellular processes, such as DNA synthesis, gene expression, and apoptosis.

TXNRD1 is widely expressed in various tissues and is localized in the cytosol of the cell. It has been implicated in several physiological and pathological processes, including inflammation, oxidative stress, cancer, and neurodegenerative diseases. Inhibition of TXNRD1 has been shown to have potential therapeutic benefits in various disease models, making it an attractive target for drug development.

In the context of cell biology, "S phase" refers to the part of the cell cycle during which DNA replication occurs. The "S" stands for synthesis, reflecting the active DNA synthesis that takes place during this phase. It is preceded by G1 phase (gap 1) and followed by G2 phase (gap 2), with mitosis (M phase) being the final stage of the cell cycle.

During S phase, the cell's DNA content effectively doubles as each chromosome is replicated to ensure that the two resulting daughter cells will have the same genetic material as the parent cell. This process is carefully regulated and coordinated with other events in the cell cycle to maintain genomic stability.

Vidarabine phosphate is a antiviral medication used to treat herpes simplex encephalitis, a severe form of brain infection caused by the herpes simplex virus. It works by inhibiting the replication of the virus in human cells. Vidarabine phosphate is the salt of vidarabine, which is a nucleoside analogue that gets incorporated into viral DNA during replication, leading to termination of the DNA chain and preventing further viral reproduction. It is administered through intravenous (IV) infusion in a hospital setting.

Flavin Mononucleotide (FMN) is a coenzyme that plays a crucial role in biological oxidation-reduction reactions. It is derived from the vitamin riboflavin (also known as vitamin B2) and is composed of a flavin molecule bonded to a nucleotide. FMN functions as an electron carrier, accepting and donating electrons in various metabolic pathways, including the citric acid cycle and the electron transport chain, which are essential for energy production in cells. It also participates in the detoxification of harmful substances and contributes to the maintenance of cellular redox homeostasis. FMN can exist in two forms: the oxidized form (FMN) and the reduced form (FMNH2), depending on its involvement in redox reactions.

Bivalvia is a class of mollusks, also known as "pelecypods," that have a laterally compressed body and two shells or valves. These valves are hinged together on one side and can be opened and closed to allow the animal to feed or withdraw into its shell for protection.

Bivalves include clams, oysters, mussels, scallops, and numerous other species. They are characterized by their simple body structure, which consists of a muscular foot used for burrowing or anchoring, a soft mantle that secretes the shell, and gills that serve both as respiratory organs and feeding structures.

Bivalves play an important role in aquatic ecosystems as filter feeders, helping to maintain water quality by removing particles and organic matter from the water column. They are also commercially important as a source of food for humans and other animals, and their shells have been used historically for various purposes such as tools, jewelry, and building materials.

Ribonucleotide+reductases at the U.S. National Library of Medicine Medical Subject Headings (MeSH) The ribonucleotide reductase ... Ribonucleotide reductase (RNR), also known as ribonucleoside diphosphate reductase (rNDP), is an enzyme that catalyzes the ... "Ribonucleotide activation by enzyme ribonucleotide reductase: understanding the role of the enzyme". Journal of Computational ... "Dehydration of ribonucleotides catalyzed by ribonucleotide reductase: the role of the enzyme". Biophysical Journal. 90 (6): ...
... s are a family of anti-cancer drugs that interfere with the growth of tumor cells by blocking ... "Tezacitabine monohydrate". Ribonucleotide reductase inhibitor entry in the public domain NCI Dictionary of Cancer Terms This ... Ribonucleotide reductase Zahedi Avval F, Berndt C, Pramanik A, Holmgren A (January 2009). "Mechanism of inhibition of ... "Short-term treatment with novel ribonucleotide reductase inhibitors Trimidox and Didox reverses late-stage murine retrovirus- ...
Jordan A, Reichard P (June 1998). "Ribonucleotide reductases". Annual Review of Biochemistry. 67 (1): 71-98. doi:10.1146/ ... Hz2V047 and Hz2V065 are most similar to SlNPV sibonucleotide reductase large (RR1) and small subunit (RR2) respectively. RR1 ... Schnell JR, Dyson HJ, Wright PE (2004-06-09). "Structure, dynamics, and catalytic function of dihydrofolate reductase". Annual ... Hz2V111 is a homologue of Heliothis virescens dihydrofolate reductase (DHFR) and to herpesvirus DHFR. DHFR reduces ...
Ribonucleotide reductase (RNR) is the enzyme responsible for converting NTPs to dNTPs. Given that dNTPs are used in DNA ... Stubbe J (1990). "Ribonucleotide reductases: amazing and confusing" (PDF). The Journal of Biological Chemistry. 265 (10): 5329- ... Kolberg M, Strand KR, Graff P, Andersson KK (June 2004). "Structure, function, and mechanism of ribonucleotide reductases". ... Ahmad MF, Dealwis CG (2013). "The Structural Basis for the Allosteric Regulation of Ribonucleotide Reductase". Oligomerization ...
The reduction of ribonucleotides to deoxyribonucleotides is catalyzed by ribonucleotide reductase. Ribonucleotide reductase ( ... Ribonucleotide reductase is controlled by allosteric interactions. Once dATP binds to ribonucleotide reductase, the overall ... Deoxyribonucleotides, formed by reducing ribonucleotides with the enzyme ribonucleotide reductase (RNR), are essential building ... ISBN 978-93-80026-37-4. Cendra Mdel, M; Juárez, A; Torrents, E (2012). "Biofilm modifies expression of ribonucleotide reductase ...
Torrents, Eduard (2014). "Ribonucleotide reductases: essential enzymes for bacterial life". Frontiers in Cellular and Infection ... Additionally, ribonucleoside-diphosphate reductase is capable of binding and catalyzing both the formation of ... diphosphocholine which is catalyzed by the presence of ribonucleoside-diphosphate reductase. ... deoxyribonucleotides from ribonucleotide. DNA Cofactor Cytosine MeSH term, accessed Dec. 31, 2012 Kandeel, Mahmoud; Al-Taher, ...
... ribonucleotide reductase; leucine aminopeptidase; urease; arginase; several phosphatases and phosphoesterases-that includes two ...
This conversion is catalysed by ribonucleotide reductase (see figure). Thiyl intermediates also are produced by the oxidation ... "Radical Initiation in the Class I Ribonucleotide Reductase: Long-Range Proton-Coupled Electron Transfer?". Chem. Rev. 103 (6): ...
Elledge accidentally discovered the RNR2 gene and protein in yeast, which belongs to the family of ribonucleotide reductase, ... "RNR2 ribonucleotide-diphosphate reductase subunit RNR2 [ Saccharomyces cerevisiae S288C ]". National Center for Biotechnology ... "Identification and isolation of the gene encoding the small subunit of ribonucleotide reductase from Saccharomyces cerevisiae: ...
Ribonucleotide-diphosphate reductase subunit M2 B is an enzyme that in humans is encoded by the RRM2B gene. The gene encoding ... Zhou B, Liu X, Mo X, Xue L, Darwish D, Qiu W, Shih J, Hwu EB, Luh F, Yen Y (October 2003). "The human ribonucleotide reductase ... Xue L, Zhou B, Liu X, Qiu W, Jin Z, Yen Y (March 2003). "Wild-type p53 regulates human ribonucleotide reductase by protein- ... "Entrez Gene: RRM2B ribonucleotide reductase M2 B (TP53 inducible)". Copeland WC (2012). "Defects in mitochondrial DNA ...
"Structural Basis for Activation of Class Ib Ribonucleotide Reductase". Science. 329 (5998): 1526-1530. Bibcode:2010Sci... ...
... is a ribonucleotide reductase inhibitor. It is a synthetic purine nucleoside analogue with potential ... Tsimberidou AM, Alvarado Y, Giles FJ (August 2002). "Evolving role of ribonucleoside reductase inhibitors in hematologic ...
... it inhibits the enzyme ribonucleotide reductase (RNR), which is needed to create new DNA nucleotides. The lack of nucleotides ... "Understanding ribonucleotide reductase inactivation by gemcitabine". Chemistry: A European Journal. 13 (30): 8507-8515. doi: ...
"Redox Property of Ribonucleotide Reductase Small Subunit M2 and p53R2". Redox property of ribonucleotide reductase small ... Ribonucleoside-diphosphate reductase subunit M2, also known as ribonucleotide reductase small subunit, is an enzyme that in ... This gene encodes one of two non-identical subunits for ribonucleotide reductase. This reductase catalyzes the formation of ... "Entrez Gene: ribonucleotide reductase M2". Pavloff N, Rivard D, Masson S, Shen SH, Mes-Masson AM (1992). "Sequence analysis of ...
... via the enzyme ribonucleotide reductase. The TGMP, TGDP and TGTP are collectively named 6-thioguanine nucleotides (6-TGN). 6- ...
Unlike other glutaredoxins, glutaredoxin 2 (Grx2) cannot reduce ribonucleotide reductase. Grx2 has significantly higher ...
... "c-Myc initiates illegitimate replication of the ribonucleotide reductase R2 gene". Oncogene. 21 (6): 909-20. doi:10.1038/sj.onc ...
It belongs to the family of drugs called ribonucleotide reductase inhibitors. 3AP is a potent inhibitor of ribonucleotide ... that the iron chelate is the active species that quenches the active site tyrosyl radical required by ribonucleotide reductase ... Tsimberidou AM; Alvarado Y; Giles FJ (August 2002). "Evolving role of ribonucleoside reductase inhibitors in hematologic ... reductase, the rate determining enzyme in the supply of deoxynucleotides (DNA building blocks) for DNA synthesis. DNA synthesis ...
"Computational studies of reaction mechanisms of methane monooxygenase and ribonucleotide reductase". Journal of Computational ...
... (EC 1.17.4.2, ribonucleotide reductase, 2'-deoxyribonucleoside-triphosphate:oxidized- ... Lammers, M.; Follmann, H. (1983). "The ribonucleotide reductases - a unique group of metalloenzymes essential for cell- ... Goulian M, Beck WS (September 1966). "Purification and properties of cobamide-dependent ribonucleotide reductase from ... Blakley RL (May 1965). "Cobamides and ribonucleotide reduction. I. Cobamide stimulation of ribonucleotide reduction in extracts ...
The Stirrup protein domain is found in prokaryotic protein ribonucleotide reductases. It obtains its name due to its ... It allows for binding of the reductase to DNA via electrostatic interactions, since it has a predominance of positive charges ... "Ribonucleoside-diphosphate reductase". UniProt. Retrieved 14 August 2012. This article incorporates text from the public domain ...
Nitric oxide-induced cytostasis targets ribonucleotide reductase by rapid and reversible inhibition. However, other studies ...
... inhibits DNA synthesis by interfering with ribonucleotide reductase and DNA polymerase. It is active against both ...
This may involve blocking the action of an iron-dependent ribonucleotide reductase. It may also inhibit transcription of serine ... Hydroxyurea (HU) is a small molecule drug that inhibits the enzyme ribonucleotide reductase (RNR), preventing the catalysis of ... converting deoxyribonucleotides (DNTs) to ribonucleotides. It is hypothesized that there is tyrosyl free radical within RNR ...
... is generated from ribose 5-phosphate by enzymes called ribonucleotide reductases. These enzymes catalyse the ...
These dATP molecules then inhibit ribonucleotide reductase, which prevents of DNA synthesis. Huntington's disease: this ... 4-hydroxy-tetrahydrodipicolinate reductase catalyzes the reduction of (2S,4S)-4-hydroxy-2,3,4,5-tetrahydrodipicolinate by NADPH ... Pyrroline-5-carboxylate is further reduced by the enzyme pyrroline-5-carboxylate reductase (P5CR) to yield a proline amino acid ... This conversion involves the enzyme ribonucleoside triphosphate reductase. This reaction that removes the 2'-OH of the ribose ...
nrdJ RNAs occur upstream of nrdJ genes, which encode class II ribonucleotide reductase. The RNAs therefore likely function as ...
Gemcitabine diphosphate inhibits ribonucleotide reductase, resulting in reductions in deoxynucleotide concentrations, including ... Pemetrexed inhibits thymidylate synthase, dihydrofolate reductase and glycinamide ribonucleotide formyltransferase. Pemetrexed ...
... s act as electron donors to peroxidases and ribonucleotide reductase. The related glutaredoxins share many of the ... Oxidized Trx1 is then reduced by thioredoxin reductase, which in turn is reduced by NADPH as described above. Trx1 can regulate ... The thioredoxins are maintained in their reduced state by the flavoenzyme thioredoxin reductase, in a NADPH-dependent reaction ... Arnér ES, Holmgren A (October 2000). "Physiological functions of thioredoxin and thioredoxin reductase". European Journal of ...
... (proposed tradename Xcytrin) is an inhibitor of thioredoxin reductase and ribonucleotide reductase. It has ...
Ribonucleotide+reductases at the U.S. National Library of Medicine Medical Subject Headings (MeSH) The ribonucleotide reductase ... Ribonucleotide reductase (RNR), also known as ribonucleoside diphosphate reductase (rNDP), is an enzyme that catalyzes the ... "Ribonucleotide activation by enzyme ribonucleotide reductase: understanding the role of the enzyme". Journal of Computational ... "Dehydration of ribonucleotides catalyzed by ribonucleotide reductase: the role of the enzyme". Biophysical Journal. 90 (6): ...
2020) Structure of a trapped radical transfer pathway within a ribonucleotide reductase holocomplex Science (New York, N.Y.) ... 2001) Structure and function of the radical enzyme ribonucleotide reductase Progress in Biophysics and Molecular Biology 77:177 ... 2003) Pre-steady-state and steady-state kinetic analysis of E. coli class I ribonucleotide reductase Biochemistry 42:10071- ... 2012) Tangled up in knots: structures of inactivated forms of E. coli class Ia ribonucleotide reductase Structure (London, ...
Antisense 20-mer oligonucleotide complementary to R2 component of ribonucleotide reductase mRNA. April 12, 2017. ... Antisense 20-mer oligonucleotide complementary to R2 component of ribonucleotide reductase mRNA ...
Bacterial ribonucleotide reductases (RNRs) play a significant role in the formation. immune Uncategorized Fesoterodine fumarate ... Bacterial ribonucleotide reductases (RNRs) play a significant role in the formation of dNTPs and their expression is normally ... Ribonucleotide PPARG reductases (RNRs) signify one such important course of enzymes that catalyses the transformation of most ... four ribonucleotides (rNTPs) to their matching 2-deoxyribonucleotides (dNTPs) offering the precursors for DNA synthesis and ...
Human RRM1(Ribonucleotide Reductase M1) ELISA Kit. Contact us: [email protected]. Human Ribonucleotide Reductase M1 (RRM1) ... Ribonucleotide reductase M1 polypeptide (RRM1) is one of two non-identical subunits for ribonucleoside-diphosphate reductase, ... Ribonucleotide reductase M1 polypeptide (RRM1) is one of two non-identical subunits for ribonucleoside-diphosphate reductase, ... Ribonucleotide reductase M1 polypeptide (RRM1) is one of two non-identical subunits for ribonucleoside-diphosphate reductase, ...
Mechanism and allosteric regulation in ribonucleotide reductases. *Derek Logan. Ribonucleotide reductases (RNRs) are essential ... as only one RNR catalyses the reduction of all four ribonucleotides under given physiological conditions). dNTP products ...
... induction of the Cdk-inhibitor p21Cip/Waf and inhibition of ribonucleotide reductase activity resulting in reduced dCTP and ... ribonucleotide reductase activity by 14C-cytidine incorporation into nascent DNA and cell-cycle distribution by FACS. Apoptosis ... A) Measurement of the in situ effect of di-GA on ribonucleotide reductase (RR) activity. HL-60 cells were incubated with 1, 2.5 ... Gallic acid inhibits ribonucleotide reductase and cyclooxygenases in human HL-60 promyelocytic leukemia cells. Cancer Lett 245 ...
... slows DNA replication and induces replication stress by downregulating the regulatory subunit RRM2 of ribonucleotide reductase ... Ribonucleotide reductases: radical enzymes with suicidal tendencies. Chem Biol. 1995;2:793-801. ... Targeting IGF perturbs global replication through ribonucleotide reductase dysfunction. Cancer Res. 2021;81:2128-41. ... ribonucleotide reductase subunit M1 (RRM1) and M2 (RRM2) [16]. Acting via both PI3K-AKT and MEK-ERK-JUN pathways, we showed ...
Ribonucleotide reductase regulatory subunit M2 drives glioblastoma TMZ resistance through Ribonucleotide reductase regulatory ... Of interest was the increased expression of ribonucleotide reductase regulatory subunit M2 (RRM2), which we found to regulate ...
Resveratrol is a remarkable inhibitor of ribonucleotide reductase.Jan 16, 1998. Click here to read the entire abstract. ...
Ribonucleotide Reductases / genetics * Ribonucleotide Reductases / metabolism * Saccharomyces cerevisiae / drug effects * ...
We then identified ribonucleotide reductase M2 (RRM2), the iron-dependent subunit of ribonucleotide reductase (RNR), as one ... Keywords: Ewing sarcoma, ribonucleotide reductase, ciclopirox, iron chelator. Received: June 28, 2016 Accepted: August 13, 2016 ... Gene expression signature based screening identifies ribonucleotide reductase as a candidate therapeutic target in Ewing ...
NrdR Controls Differential Expression of the Escherichia coli Ribonucleotide Reductase Genes journal, May 2007 * Torrents, ...
... are produced by reduction of the corresponding ribonucleotides catalyzed by ribonucleotide reductase. In mammals as in ... the plant ribonucleotide reductase seems to be allosterically regulated by positive (ATP) and negative (dATP) effectors. ... Protein R1 is the proper reductase as it contains, in the substrate binding site, the reducing active cysteine pair. Protein R2 ... are produced by reduction of the corresponding ribonucleotides catalyzed by ribonucleotide reductase. In mammals as in ...
Stubbe, J. A., & Seyedsayamdost, M. R. (2019). Discovery of a New Class i Ribonucleotide Reductase with an Essential DOPA ... Stubbe, Jo Anne ; Seyedsayamdost, Mohammad R. / Discovery of a New Class i Ribonucleotide Reductase with an Essential DOPA ... Discovery of a New Class i Ribonucleotide Reductase with an Essential DOPA Radical and NO Metal as an Initiator of Long-Range ... Discovery of a New Class i Ribonucleotide Reductase with an Essential DOPA Radical and NO Metal as an Initiator of Long-Range ...
Gao, W. Y., Zhou, B. S., Johns, D. G., Mitsuya, H., & Yen, Y. (1998). Role of the M2 subunit of ribonucleotide reductase in ... Gao, WY, Zhou, BS, Johns, DG, Mitsuya, H & Yen, Y 1998, Role of the M2 subunit of ribonucleotide reductase in regulation by ... 深入研究「Role of the M2 subunit of ribonucleotide reductase in regulation by hydroxyurea of the activity of the anti-HIV-1 agent 2 ... Role of the M2 subunit of ribonucleotide reductase in regulation by hydroxyurea of the activity of the anti-HIV-1 agent 2,3- ...
RRM2B: ribonucleotide reductase regulatory TP53 inducible subunit M2B. *RS1: retinoschisin 1. *RSPO2: R-spondin 2 ...
Ribonucleotide reductase inhibitors (hydroxyurea, cytarabine arabinoside) * Drugs that affect cobalamin metabolism ( p- ... dihydrofolate reductase inhibitors (trimethoprim, pyrimethamine), methotrexate and other antifolates, sulfonamides (competitive ...
Ribonucleotide Reductases. Chimploy K, G Díaz D, Li Q, Carter O, Dashwood W-M, Mathews CK, Williams DE, Bailey GS, Dashwood RH ... E2F4 and ribonucleotide reductase mediate S-phase arrest in colon cancer cells treated with chlorophyllin.. Int J Cancer. 125(9 ... E2F4 and ribonucleotide reductase mediate S-phase arrest in colon cancer cells treated with chlorophyllin.. Int J Cancer. 125(9 ... E2F4 and ribonucleotide reductase mediate S-phase arrest in colon cancer cells treated with chlorophyllin.. Int J Cancer. 125(9 ...
Family a.25.1.2: Ribonucleotide reductase-like [47253] (9 proteins). *. Protein Ribonucleotide reductase R2 [47257] (10 species ... from a.25.1.2 Ribonucleotide reductase R2: *Species Chlamydia trachomatis [TaxId:813] from a.25.1.2 Ribonucleotide reductase R2 ... More info for Species Chlamydia trachomatis [TaxId:813] from a.25.1.2 Ribonucleotide reductase R2. Timeline for Species ... Species Chlamydia trachomatis [TaxId:813] from a.25.1.2 Ribonucleotide reductase R2 appears in SCOPe 2.07. ...
The proteins involved are HNH endonuclease and ribonucleotide reductase. To search for repetitive sequences in the genome which ... an hnh homing endonuclease gene embedded within a ribonucleotide reductase gene of phage Aeh1. J. Bacteriol. 189, 4648-4661. ...
He Z, Hu X, Liu W, Dorrance A, Garzon R, Houghton PJ, Shen C*: P53 suppresses ribonucleotide reductase via inhibiting mTORC1. ...
The reduced state of T[SH]2 is maintained by NADPH-dependent trypanothione reductase (TryR) by recycling trypanothione ... The reduced state of T[SH]2 is maintained by NADPH-dependent trypanothione reductase (TryR) by recycling trypanothione ... Trypanothione-dependent synthesis of deoxyribonucleotides by Trypanosoma brucei ribonucleotide reductase. J. Biol. Chem. 276, ... 1991). X-ray structure of trypanothione reductase from Crithidia fasciculata at 2.4-Å resolution. Proc. Natl. Acad. Sci. U S A ...
Regulators of ribonucleotide reductase inhibit Ty1 mobility in Saccharomyces cerevisiae. Mobile DNA. Nov 22;1(1):23. ...
Ribonucleotide Reductase, subunit A 1.10.620.20 Ribonucleotide Reductase, subunit A Domain Context. .structure-view-container ...
... revealing that endosymbionts and pathogens that lack ribonucleotide reduction avoid loss of deoxyribonucleotides to central ... Deletion of ribonucleotide reductase (RNR) genes in E. coli.. (A) Schematic of each of the three RNR operons in E. coli and the ... RT-PCR indicates that ribonucleotide reductase (RNR) genes are not expressed in ∆RNR.. RT-PCR using primers for (a) nrdA, (b) ... Abbreviations: RNR-ribonucleotide reductase; dNs-deoxyribonucleosides; DR1P-2-deoxyribose 1-phosphate; DR5P-2-deoxyribose 5- ...
Dwivedi, B.; Xue, B.; Lundin, D.; Edwards, R.A.; Breitbart, M. A bioinformatic analysis of ribonucleotide reductase genes in ... which codes for a ribonucleotide reductase and is shared mainly among members of the families Myoviridae, Herpesviridae, and ... Ribonucleotide reductases reveal novel viral diversity and predict biological and ecological features of unknown marine viruses ...
... dihydrofolate reductase, and GARFT. Explore a compelling case of pemetrexeds efficacy in refractory non-small cell lung cancer ... It also inhibits dihydrofolate reductase (DHFR) and glycinamide ribonucleotide formyl transferase (GARFT). We reported an ...
Induction of the mouse ribonucleotide reductase R1 and R2 genes in response to DNA damage by UV light. ... An S-phase specific release from a transcriptional block regulates the expression of mouse ribonucleotide reductase R2 subunit ... S Phase-specific transcription of the mouse ribonucleotide reductase R2 gene requires both a proximal repressive E2F-binding ... Gene structure and regulation of the expression of the R1 and R2 subunits of mouse ribonucleotide reductase. ...
  • We then identified ribonucleotide reductase M2 (RRM2), the iron-dependent subunit of ribonucleotide reductase (RNR), as one mediator of iron chelator toxicity in Ewing sarcoma cells. (oncotarget.com)
  • It further inhibited cell-cycle progression in the G1 phase by four different mechanisms: rapid downregulation of cyclin D1, induction of Chk2 with simultaneous downregulation of Cdc25A, induction of the Cdk-inhibitor p21 Cip/Waf and inhibition of ribonucleotide reductase activity resulting in reduced dCTP and dTTP levels. (nature.com)
  • The dATP increase results in inhibition of ribonucleotide reductase and underproduction of other deoxyribonucleotides. (msdmanuals.com)
  • Ribonucleotide reductase (RNR), also known as ribonucleoside diphosphate reductase (rNDP), is an enzyme that catalyzes the formation of deoxyribonucleotides from ribonucleotides. (wikipedia.org)
  • The enzyme ribonucleotide reductase (RNR) catalyzes the de novo synthesis of dNDPs. (wikipedia.org)
  • Description: This is Double-antibody Sandwich Enzyme-linked immunosorbent assay for detection of Human Ribonucleotide Reductase M1 (RRM1) in tissue homogenates, cell lysates and other biological fluids. (allelisakits.com)
  • Description: Enzyme-linked immunosorbent assay based on the Double-antibody Sandwich method for detection of Human Ribonucleotide Reductase M1 (RRM1) in samples from tissue homogenates, cell lysates and other biological fluids with no significant corss-reactivity with analogues from other species. (allelisakits.com)
  • c) activity is stimulated by thioredoxin and ATP and is inhibited by dATP, showing that as in the mammalian enzyme, the plant ribonucleotide reductase seems to be allosterically regulated by positive (ATP) and negative (dATP) effectors. (hal.science)
  • There is an enzyme, ribonucleotide reductase, which splits of OH as H2O and attaches another H to the C atom. (khanacademy.org)
  • Methyl-hydroxylamine as an efficacious antibacterial agent that targets the ribonucleotide reductase enzyme. (ibecbarcelona.eu)
  • Deoxy-ATP (dATP) can reach toxic levels that inhibit ribonucleotide reductase, an enzyme essential for synthesis of DNA precursors. (medscape.com)
  • It is a pyrimidine antimetabolite that nhibits DNA polymerase and ribonucleotide reductase, which in turn inhibit DNA synthesis. (medscape.com)
  • We recently reported that genetic or pharmacological inhibition of insulin-like growth factor receptor (IGF-1R) slows DNA replication and induces replication stress by downregulating the regulatory subunit RRM2 of ribonucleotide reductase, perturbing deoxynucleotide triphosphate (dNTP) supply. (nature.com)
  • RNR contains two subunits: ribonucleotide reductase subunit M1 (RRM1) and M2 (RRM2) [ 16 ]. (nature.com)
  • Of interest was the increased expression of ribonucleotide reductase regulatory subunit M2 (RRM2), which we found to regulate dGTP and dCTP production vital for DNA damage response during TMZ therapy . (bvsalud.org)
  • Bacterial ribonucleotide reductases (RNRs) play a significant role in the formation of dNTPs and their expression is normally regulated with the transcription factors NrdR and Hair. (immune-source.com)
  • Ribonucleotide reductases (RNRs) are essential enzymes for all life by virtue of their central role in the de novo synthesis of deoxyribonucleotides, the building blocks for DNA synthesis. (lu.se)
  • This metabolite appears to act by inhibiting DNA polymerase alpha, ribonucleotide reductase and DNA primase, thus inhibiting DNA synthesis. (guidelinecentral.com)
  • Description: A sandwich quantitative ELISA assay kit for detection of Mouse Ribonucleotide Reductase M1 (RRM1) in samples from tissue homogenates or other biological fluids. (allelisakits.com)
  • Protein activation and expression were analysed by western blotting, deoxyribonucleoside triphosphate levels by HPLC, ribonucleotide reductase activity by 14 C-cytidine incorporation into nascent DNA and cell-cycle distribution by FACS. (nature.com)
  • Protein R1 is the proper reductase as it contains, in the substrate binding site, the reducing active cysteine pair. (hal.science)
  • The data show that ERCC5, encoding Xeroderma pigmentosum protein G (XPG), essential for DNA excision repair, and ribonucleotide reductase subunit M1 (RNRM1), encoding a gene necessary for providing the nucleotides needed for DNA repair, were down-regulated in cells treated with diazinon. (cdc.gov)
  • It also inhibits dihydrofolate reductase (DHFR) and glycinamide ribonucleotide formyl transferase (GARFT). (scirp.org)
  • dGTP inhibits ribonucleotide reductase, which is needed for synthesis of deoxynucleotides. (medscape.com)
  • The MDR superfamily with ~350-residue subunits contains the classical liver alcohol dehydrogenase (ADH), quinone reductase, leukotriene B4 dehydrogenase and many more forms. (researchgate.net)
  • The ribonucleotide reductase inhibitor hydroxyurea exhibits potent synergism, even at low, non-cytotoxic concentrations, with the anti-HIV-1 dideoxynucleoside 2',3'-dideoxyinosine, bringing about failure of HIV DNA synthesis and, thus, of HIV replication. (tmu.edu.tw)
  • Ribonucleotide reductase regulatory subunit M2 drives glioblastoma TMZ resistance through modulation of dNTP production. (bvsalud.org)
  • In all living organisms, deoxyribonucleotides, the DNA precursors, are produced by reduction of the corresponding ribonucleotides catalyzed by ribonucleotide reductase. (hal.science)
  • Deletion of ribonucleotide reductase (RNR) genes in E. coli . (elifesciences.org)
  • RT-PCR indicates that ribonucleotide reductase (RNR) genes are not expressed in ∆RNR. (elifesciences.org)
  • Activity is regulated on two levels: overall activity and substrate specificity (as only one RNR catalyses the reduction of all four ribonucleotides under given physiological conditions). (lu.se)
  • By selecting organisms resistant to the novel inhibitors and sequencing their genomes, we identified a new therapeutic target, the class Ia ribonucleotide reductase (RNR). (elifesciences.org)
  • 60 known mutations) results in accumulation of adenosine , which is converted to its ribonucleotide and deoxyribonucleotide (dATP) forms by cellular kinases. (msdmanuals.com)
  • The authors present two small molecules that specifically target the essential ribonucleotide reductase of the causative agent of gonorrhea. (elifesciences.org)
  • Stubbe, JA & Seyedsayamdost, MR 2019, ' Discovery of a New Class i Ribonucleotide Reductase with an Essential DOPA Radical and NO Metal as an Initiator of Long-Range Radical Transfer ', Biochemistry , vol. 58, no. 6, pp. 435-437. (princeton.edu)
  • An active ribonucleotide reductase from Arabidopsis thaliana cloning, expression and characterization of the large subunit. (hal.science)
  • Description: A sandwich ELISA kit for detection of Ribonucleotide Reductase M1 from Human in samples from blood, serum, plasma, cell culture fluid and other biological fluids. (allelisakits.com)
  • Short-chain dehydrogenases/reductases (SDRs) constitute a large family of NAD(P)(H)-dependent oxidoreductases, sharing sequence motifs and displaying similar mechanisms. (researchgate.net)
  • Studying seven cases of profound mtDNA depletion (1-2% residual mtDNA in muscle) in four unrelated families, we have found nonsense, missense and splice-site mutations and in-frame deletions of the RRM2B gene, encoding the cytosolic p53-inducible ribonucleotide reductase small subunit. (nih.gov)
  • This phenotype reflected unanticipated regulation of global replication by IGF1 mediated via AKT, MEK/ERK, and JUN to influence expression of ribonucleotide reductase (RNR) subunit RRM2. (ox.ac.uk)
  • We recently reported that genetic or pharmacological inhibition of insulin-like growth factor receptor (IGF-1R) slows DNA replication and induces replication stress by downregulating the regulatory subunit RRM2 of ribonucleotide reductase, perturbing deoxynucleotide triphosphate (dNTP) supply. (nature.com)
  • RNR contains two subunits: ribonucleotide reductase subunit M1 (RRM1) and M2 (RRM2) [ 16 ]. (nature.com)
  • An active ribonucleotide reductase from Arabidopsis thaliana cloning, expression and characterization of the large subunit. (hal.science)
  • Ribonucleotide reductase M2 (RRM2) is a small subunit in ribonucleotide reductases , which participate in nucleotide metabolism and catalyze the conversion of nucleotides to deoxynucleotides, maintaining the dNTP pools for DNA biosynthesis , repair, and replication. (bvsalud.org)
  • 10. ATR-CHK1-E2F3 signaling transactivates human ribonucleotide reductase small subunit M2 for DNA repair induced by the chemical carcinogen MNNG. (nih.gov)
  • 13. Ribonucleotide Reductase Requires Subunit Switching in Hypoxia to Maintain DNA Replication. (nih.gov)
  • 14. A Single Conserved Residue Mediates Binding of the Ribonucleotide Reductase Catalytic Subunit RRM1 to RRM2 and Is Essential for Mouse Development. (nih.gov)
  • The data show that ERCC5, encoding Xeroderma pigmentosum protein G (XPG), essential for DNA excision repair, and ribonucleotide reductase subunit M1 (RNRM1), encoding a gene necessary for providing the nucleotides needed for DNA repair, were down-regulated in cells treated with diazinon. (cdc.gov)
  • Ribonucleotide reductases (RNRs) are radical enzymes that convert ribonucleotides (the building blocks of RNA) to deoxyribonucleotides (the building blocks of DNA). (nih.gov)
  • Ribonucleotide reductases are essential enzymes which synthesize deoxyribonucleotides used in the replication of DNA. (ibecbarcelona.eu)
  • Among the last ones, it is remarkable the inhibition of ribonucleotide reductases (RNRs), enzymes that transform ribonucleoside diphosphates into deoxyribonucleoside diphospates to give the basic constituents of DNA 9 . (uninet.edu)
  • Every organism uses ribonucleotide reductase (RNR) enzymes to make the nucleotide building blocks needed for DNA replication and repair," says lead author Amie Boal, an assistant professor of chemistry and of biochemistry and molecular biology at Penn State. (futurity.org)
  • 12. mTORC2 regulates ribonucleotide reductase to promote DNA replication and gemcitabine resistance in non-small cell lung cancer. (nih.gov)
  • In this talk, the conformational gymnastics involved in ribonucleotide reduction will be considered. (nih.gov)
  • This study identifies regulation of ribonucleotide reductase function and dNTP supply by IGFs and demonstrates that IGF axis blockade induces replication stress and reciprocal codependence on ATM. (ox.ac.uk)
  • Ribonucleoside diphosphate reductase (EC 1.17.4.1) (RR) is a potential target for antineoplastic agents due to its crucial role in DNA replication and repair. (tmu.edu.tw)
  • P.229 right column bottom paragraph: 'The mechanism for replication arrest when RNR [ribonucleotide reductase] is inhibited remains unknown. (harvard.edu)
  • If RNR inhibition resulted in significant expansion of the rNTP pools, it is possible that an increased rNTP/dNTP ratio might result in misincorporation of ribonucleotides into DNA and thereby trigger a replication arrest. (harvard.edu)
  • The invariant active site residue Glu441 in protein R1 of ribonucleotide reductase from Escherichia coli has been engineered to alanine, aspartic acid, and glutamic acid. (proteopedia.org)
  • A new mechanism-based radical intermediate in a mutant R1 protein affecting the catalytically essential Glu441 in Escherichia coli ribonucleotide reductase. (proteopedia.org)
  • Ribonucleotide reductase (RR) is an α(n)β(n) (RR1-RR2) complex that maintains balanced dNTP pools by reducing NDPs to dNDPs. (nih.gov)
  • 2. Implication of checkpoint kinase-dependent up-regulation of ribonucleotide reductase R2 in DNA damage response. (nih.gov)
  • His current research interests focus on the identification of new antimicrobial therapies and unravel the molecular mechanism underlying the transcripcional regulation of bacterial ribonucleotide reductase genes. (ibecbarcelona.eu)
  • 7. Cross-species genomic and functional analyses identify a combination therapy using a CHK1 inhibitor and a ribonucleotide reductase inhibitor to treat triple-negative breast cancer. (nih.gov)
  • Protein R1 is the proper reductase as it contains, in the substrate binding site, the reducing active cysteine pair. (hal.science)
  • The tyrosyl free radical in ribonucleotide reductase. (nih.gov)
  • 1. A functional approach reveals a genetic and physical interaction between ribonucleotide reductase and CHK1 in mammalian cells. (nih.gov)
  • Comprehensive phylogenetic analysis of the ribonucleotide reductase family reveals an ancestral clade " published in eLife Digest Oct. 4. (lightsources.org)
  • 2009. E2F4 and ribonucleotide reductase mediate S-phase arrest in colon cancer cells treated with chlorophyllin. . (oregonstate.edu)
  • Ribonucleotide reductase (RNR) and pyruvate formate lyase (PFL) are structurally similar and are thought to have diverged from a common ancestral domain. (nih.gov)
  • Serum ribonucleotide reductase M2 is a potential biomarker for diagnosing and monitoring liver fibrosis in chronic hepatitis B patients. (amedeo.com)