An essential amino acid that is required for the production of HISTAMINE.
An enzyme that catalyzes the decarboxylation of histidine to histamine and carbon dioxide. It requires pyridoxal phosphate in animal tissues, but not in microorganisms. EC
Preservative for wines, soft drinks, and fruit juices and a gentle esterifying agent.
An enzyme that catalyzes the first step of histidine catabolism, forming UROCANIC ACID and AMMONIA from HISTIDINE. Deficiency of this enzyme is associated with elevated levels of serum histidine and is called histidinemia (AMINO ACID METABOLISM, INBORN ERRORS).
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.
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.
The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH = log 1/2[1/(H+)], where (H+) is the hydrogen ion concentration in gram equivalents per liter of solution. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)
The parts of a macromolecule that directly participate in its specific combination with another molecule.
Genetically engineered MUTAGENESIS at a specific site in the DNA molecule that introduces a base substitution, or an insertion or deletion.
An enzyme that catalyzes the first step of the pathway for histidine biosynthesis in Salmonella typhimurium. ATP reacts reversibly with 5-phosphoribosyl-1-pyrophosphate to yield N-1-(5'-phosphoribosyl)-ATP and pyrophosphate. EC
The penultimate step in the pathway of histidine biosynthesis. Oxidation of the alcohol group on the side chain gives the acid group forming histidine. Histidinol has also been used as an inhibitor of protein synthesis.
An enzyme that catalyzes the conversion of 4,5-dihydro-4-oxo-5-imidazolepropanoate to urocanate and water. EC
A family of enzymes that catalyze the conversion of ATP and a protein to ADP and a phosphoprotein.
Organic compounds that generally contain an amino (-NH2) and a carboxyl (-COOH) group. Twenty alpha-amino acids are the subunits which are polymerized to form proteins.
Proteins found in any species of bacterium.
Models used experimentally or theoretically to study molecular shape, electronic properties, or interactions; includes analogous molecules, computer-generated graphics, and mechanical structures.
The rate dynamics in chemical or physical systems.
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.
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 group of enzymes that catalyze the hydrolysis of diphosphate bonds in compounds such as nucleoside di- and tri-phosphates, and sulfonyl-containing anhydrides such as adenylylsulfate. (Enzyme Nomenclature, 1992) EC 3.6.
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.
A metallic element of atomic number 30 and atomic weight 65.38. It is a necessary trace element in the diet, forming an essential part of many enzymes, and playing an important role in protein synthesis and in cell division. Zinc deficiency is associated with ANEMIA, short stature, HYPOGONADISM, impaired WOUND HEALING, and geophagia. It is known by the symbol Zn.
A 27-amino acid peptide with histidine at the N-terminal and isoleucine amide at the C-terminal. The exact amino acid composition of the peptide is species dependent. The peptide is secreted in the intestine, but is found in the nervous system, many organs, and in the majority of peripheral tissues. It has a wide range of biological actions, affecting the cardiovascular, gastrointestinal, respiratory, and central nervous systems.
Measurement of this acid in the urine after oral administration of histidine provides the basis for the diagnostic test of folic acid deficiency and of megaloblastic anemia of pregnancy.
The degree of similarity between sequences of amino acids. This information is useful for the analyzing genetic relatedness of proteins and species.
The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.
An amine derived by enzymatic decarboxylation of HISTIDINE. It is a powerful stimulant of gastric secretion, a constrictor of bronchial smooth muscle, a vasodilator, and also a centrally acting neurotransmitter.
The facilitation of a chemical reaction by material (catalyst) that is not consumed by the reaction.
The color-furnishing portion of hemoglobin. It is found free in tissues and as the prosthetic group in many hemeproteins.
A naturally occurring dipeptide neuropeptide found in muscles.
Histidine substituted in any position with one or more methyl groups.
Spectroscopic method of measuring the magnetic moment of elementary particles such as atomic nuclei, protons or electrons. It is employed in clinical applications such as NMR Tomography (MAGNETIC RESONANCE IMAGING).
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.
The level of protein structure in which combinations of secondary protein structures (alpha helices, beta sheets, loop regions, and motifs) pack together to form folded shapes called domains. Disulfide bridges between cysteines in two different parts of the polypeptide chain along with other interactions between the chains play a role in the formation and stabilization of tertiary structure. Small proteins usually consist of only one domain but larger proteins may contain a number of domains connected by segments of polypeptide chain which lack regular secondary structure.
Proteins prepared by recombinant DNA technology.
Derivatives of formic acids. Included under this heading are a broad variety of acid forms, salts, esters, and amides that are formed with a single carbon carboxy group.
The relationship between the chemical structure of a compound and its biological or pharmacological activity. Compounds are often classed together because they have structural characteristics in common including shape, size, stereochemical arrangement, and distribution of functional groups.
A transfer RNA which is specific for carrying histidine to sites on the ribosomes in preparation for protein synthesis.
The study of crystal structure using X-RAY DIFFRACTION techniques. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
A colorless inorganic compound (HONH2) used in organic synthesis and as a reducing agent, due to its ability to donate nitric oxide.
Large marine mammals of the order CETACEA. In the past, they were commercially valued for whale oil, for their flesh as human food and in ANIMAL FEED and FERTILIZERS, and for baleen. Today, there is a moratorium on most commercial whaling, as all species are either listed as endangered or threatened.
The naturally occurring or experimentally induced replacement of one or more AMINO ACIDS in a protein with another. If a functionally equivalent amino acid is substituted, the protein may retain wild-type activity. Substitution may also diminish, enhance, or eliminate protein function. Experimentally induced substitution is often used to study enzyme activities and binding site properties.
In bacteria, a group of metabolically related genes, with a common promoter, whose transcription into a single polycistronic MESSENGER RNA is under the control of an OPERATOR REGION.
Stable elementary particles having the smallest known positive charge, found in the nuclei of all elements. The proton mass is less than that of a neutron. A proton is the nucleus of the light hydrogen atom, i.e., the hydrogen ion.
A heavy metal trace element with the atomic symbol Cu, atomic number 29, and atomic weight 63.55.
A conjugated protein which is the oxygen-transporting pigment of muscle. It is made up of one globin polypeptide chain and one heme group.
A thiol-containing non-essential amino acid that is oxidized to form CYSTINE.
Proteins that contain an iron-porphyrin, or heme, prosthetic group resembling that of hemoglobin. (From Lehninger, Principles of Biochemistry, 1982, p480)
A serotype of Salmonella enterica that is a frequent agent of Salmonella gastroenteritis in humans. It also causes PARATYPHOID FEVER.
Any of the processes by which cytoplasmic or intercellular factors influence the differential control of gene action in bacteria.
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.
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.
One of the non-essential amino acids commonly occurring in the L-form. It is found in animals and plants, especially in sugar cane and sugar beets. It may be a neurotransmitter.
A bright bluish pink compound that has been used as a dye, biological stain, and diagnostic aid.
An enzyme that activates histidine with its specific transfer RNA. EC
Enzymes that catalyze the addition of a carboxyl group to a compound (carboxylases) or the removal of a carboxyl group from a compound (decarboxylases). EC 4.1.1.
The region of an enzyme that interacts with its substrate to cause the enzymatic reaction.
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).
The level of protein structure in which regular hydrogen-bond interactions within contiguous stretches of polypeptide chain give rise to alpha helices, beta strands (which align to form beta sheets) or other types of coils. This is the first folding level of protein conformation.
A characteristic feature of enzyme activity in relation to the kind of substrate on which the enzyme or catalytic molecule reacts.
Enzymes that catalyze the formation of a carbon-carbon double bond by the elimination of AMMONIA. EC 4.3.1.
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.
Organic compounds that contain the (-NH2OH) radical.
Analysis of the intensity of Raman scattering of monochromatic light as a function of frequency of the scattered light.
An enzyme that catalyzes the hydrolysis of histidinol-phosphate to histidinol. One of the regulatory enzymes in histidine biosynthesis. EC
A non-essential amino acid that occurs in high levels in its free state in plasma. It is produced from pyruvate by transamination. It is involved in sugar and acid metabolism, increases IMMUNITY, and provides energy for muscle tissue, BRAIN, and the CENTRAL NERVOUS SYSTEM.
A sequence of amino acids in a polypeptide or of nucleotides in DNA or RNA that is similar across multiple species. A known set of conserved sequences is represented by a CONSENSUS SEQUENCE. AMINO ACID MOTIFS are often composed of conserved sequences.
A low-energy attractive force between hydrogen and another element. It plays a major role in determining the properties of water, proteins, and other compounds.
The art or process of comparing photometrically the relative intensities of the light in different parts of the spectrum.
A molecule that binds to another molecule, used especially to refer to a small molecule that binds specifically to a larger molecule, e.g., an antigen binding to an antibody, a hormone or neurotransmitter binding to a receptor, or a substrate or allosteric effector binding to an enzyme. Ligands are also molecules that donate or accept a pair of electrons to form a coordinate covalent bond with the central metal atom of a coordination complex. (From Dorland, 27th ed)
An essential amino acid that is physiologically active in the L-form.
A trace element with the atomic symbol Ni, atomic number 28, and atomic weight 58.69. It is a cofactor of the enzyme UREASE.
Proteins obtained from ESCHERICHIA COLI.
A change from planar to elliptic polarization when an initially plane-polarized light wave traverses an optically active medium. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
The functional hereditary units of BACTERIA.
Amino acid transporter systems capable of transporting basic amino acids (AMINO ACIDS, BASIC).
An essential amino acid. It is often added to animal feed.
An essential amino acid that is necessary for normal growth in infants and for NITROGEN balance in adults. It is a precursor of INDOLE ALKALOIDS in plants. It is a precursor of SEROTONIN (hence its use as an antidepressant and sleep aid). It can be a precursor to NIACIN, albeit inefficiently, in mammals.
Determination of the spectra of ultraviolet absorption by specific molecules in gases or liquids, for example Cl2, SO2, NO2, CS2, ozone, mercury vapor, and various unsaturated compounds. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
Theoretical representations that simulate the behavior or activity of chemical processes or phenomena; includes the use of mathematical equations, computers, and other electronic equipment.
Amino acids that are not synthesized by the human body in amounts sufficient to carry out physiological functions. They are obtained from dietary foodstuffs.
An enzyme that is found in mitochondria and in the soluble cytoplasm of cells. It catalyzes reversible reactions of a nucleoside triphosphate, e.g., ATP, with a nucleoside diphosphate, e.g., UDP, to form ADP and UTP. Many nucleoside diphosphates can act as acceptor, while many ribo- and deoxyribonucleoside triphosphates can act as donor. EC
A urine test for formiminoglutamic acid, an intermediate metabolite in L-histidine catabolism in the conversion of L-histidine to L-glutamic acid. It may be an indicator of vitamin B12 or folic acid deficiency or liver disease.
The introduction of a phosphoryl group into a compound through the formation of an ester bond between the compound and a phosphorus moiety.
A species of gram-negative, aerobic bacteria that consist of slender vibroid cells.
A group of hydrolases which catalyze the hydrolysis of monophosphoric esters with the production of one mole of orthophosphate. EC 3.1.3.
The intracellular transfer of information (biological activation/inhibition) through a signal pathway. In each signal transduction system, an activation/inhibition signal from a biologically active molecule (hormone, neurotransmitter) is mediated via the coupling of a receptor/enzyme to a second messenger system or to an ion channel. Signal transduction plays an important role in activating cellular functions, cell differentiation, and cell proliferation. Examples of signal transduction systems are the GAMMA-AMINOBUTYRIC ACID-postsynaptic receptor-calcium ion channel system, the receptor-mediated T-cell activation pathway, and the receptor-mediated activation of phospholipases. Those coupled to membrane depolarization or intracellular release of calcium include the receptor-mediated activation of cytotoxic functions in granulocytes and the synaptic potentiation of protein kinase activation. Some signal transduction pathways may be part of larger signal transduction pathways; for example, protein kinase activation is part of the platelet activation signal pathway.
Process of generating a genetic MUTATION. It may occur spontaneously or be induced by MUTAGENS.
Partial proteins formed by partial hydrolysis of complete proteins or generated through PROTEIN ENGINEERING techniques.
Photochemistry is the study of chemical reactions induced by absorption of light, resulting in the promotion of electrons to higher energy levels and subsequent formation of radicals or excited molecules that can undergo various reaction pathways.
Compounds containing 1,3-diazole, a five membered aromatic ring containing two nitrogen atoms separated by one of the carbons. Chemically reduced ones include IMIDAZOLINES and IMIDAZOLIDINES. Distinguish from 1,2-diazole (PYRAZOLES).
Extrachromosomal, usually CIRCULAR DNA molecules that are self-replicating and transferable from one organism to another. They are found in a variety of bacterial, archaeal, fungal, algal, and plant species. They are used in GENETIC ENGINEERING as CLONING VECTORS.
Anserine is a muscle fiber protein, specifically a myosin heavy chain isoform, which is predominantly found in slow-twitch, type I muscle fibers and contributes to their contractile properties, playing a role in force production and fatigue resistance.
A rather large group of enzymes comprising not only those transferring phosphate but also diphosphate, nucleotidyl residues, and others. These have also been subdivided according to the acceptor group. (From Enzyme Nomenclature, 1992) EC 2.7.

Possible role for ligand binding of histidine 81 in the second transmembrane domain of the rat prostaglandin F2alpha receptor. (1/5209)

For the five principal prostanoids PGD2, PGE2, PGF2alpha, prostacyclin and thromboxane A2 eight receptors have been identified that belong to the family of G-protein-coupled receptors. They display an overall homology of merely 30%. However, single amino acids in the transmembrane domains such as an Arg in the seventh transmembrane domain are highly conserved. This Arg has been identified as part of the ligand binding pocket. It interacts with the carboxyl group of the prostanoid. The aim of the current study was to analyze the potential role in ligand binding of His-81 in the second transmembrane domain of the rat PGF2alpha receptor, which is conserved among all PGF2alpha receptors from different species. Molecular modeling suggested that this residue is located in close proximity to the ligand binding pocket Arg 291 in the 7th transmembrane domain. The His81 (H) was exchanged by site-directed mutagenesis to Gln (Q), Asp (D), Arg (R), Ala (A) and Gly (G). The receptor molecules were N-terminally extended by a Flag epitope for immunological detection. All mutant proteins were expressed at levels between 50% and 80% of the wild type construct. The H81Q and H81D receptor bound PGF2alpha with 2-fold and 25-fold lower affinity, respectively, than the wild type receptor. Membranes of cells expressing the H81R, H81A or H81G mutants did not bind significant amounts of PGF2alpha. Wild type receptor and H81Q showed a shallow pH optimum for PGF2alpha binding around pH 5.5 with almost no reduction of binding at higher pH. In contrast the H81D mutant bound PGF2alpha with a sharp optimum at pH 4.5, a pH at which the Asp side chain is partially undissociated and may serve as a hydrogen bond donor as do His and Gln at higher pH values. The data indicate that the His-81 in the second transmembrane domain of the PGF2alpha receptor in concert with Arg-291 in the seventh transmembrane domain may be involved in ligand binding, most likely not by ionic interaction with the prostaglandin's carboxyl group but rather as a hydrogen bond donor.  (+info)

R73A and H144Q mutants of the yeast mitochondrial cyclophilin Cpr3 exhibit a low prolyl isomerase activity in both peptide and protein-folding assays. (2/5209)

Previously we reported that the R73A and H144Q variants of the yeast cyclophilin Cpr3 were virtually inactive in a protease-coupled peptide assay, but retained activity as catalysts of a proline-limited protein folding reaction [Scholz, C. et al. (1997) FEBS Lett. 414, 69-73]. A reinvestigation revealed that in fact these two mutations strongly decrease the prolyl isomerase activity of Cpr3 in both the peptide and the protein-folding assay. The high folding activities found previously originated from a contamination of the recombinant Cpr3 proteins with the Escherichia coli protein SlyD, a prolyl isomerase that co-purifies with His-tagged proteins. SlyD is inactive in the peptide assay, but highly active in the protein-folding assay.  (+info)

A possible involvement of aberrant expression of the FHIT gene in the carcinogenesis of squamous cell carcinoma of the uterine cervix. (3/5209)

To investigate involvement of an aberrant expression of the FHIT (fragile histidine triad) gene in the process of carcinogenesis and progression in cervical carcinoma, we examined its expression by the reverse transcriptase polymerase chain reaction (RT-PCR) and cDNA sequence method in 32 cervical invasive carcinomas (25 squamous cell carcinomas and seven adeno- or adenosquamous carcinomas) and 18 of its precursor lesions [four low-grade and 14 high-grade cervical intraepithelial neoplasias (CINs)]. We also examined a link between the occurrence of the aberrant expression and human papillomavirus (HPV). We detected the aberrant FHIT transcripts in 11 of 25 (44%) cervical invasive squamous cell carcinomas and in 5 of 14 (36%) high-grade CINs (CIN 2 or 3), whereas they were not found in seven non-squamous type and four low-grade CINs (CIN 1). The alteration patterns of the FHIT gene expression in high-grade CINs were virtually similar to those found in invasive carcinomas, such that the exons 5-7 were consistently deleted associated or unassociated with loss of the exon 4 and/or 8. The incidence of the aberrant expression was not related to the presence of HPV and its type. These data indicate that the aberrant expression of the FHIT gene is observed in precursor lesions of cervical carcinoma as well as invasive carcinomas, with its incidence not increasing with advance of clinical stage. Given the squamous cell type dominant expression, the aberrant expression may play a critical role in the generation of squamous cell carcinoma of the uterine cervix, but not the consequence of the progression of the cancer.  (+info)

Breaking the low barrier hydrogen bond in a serine protease. (4/5209)

The serine protease subtilisin BPN' is a useful catalyst for peptide synthesis when dissolved in high concentrations of a water-miscible organic co-solvent such as N,N-dimethylformamide (DMF). However, in 50% DMF, the k(cat) for amide hydrolysis is two orders of magnitude lower than in aqueous solution. Surprisingly, the k(cat) for ester hydrolysis is unchanged in 50% DMF. To explain this alteration in activity, the structure of subtilisin 8397+1 was determined in 20, 35, and 50% (v/v) DMF to 1.8 A resolution. In 50% DMF, the imidazole ring of His64, the central residue of the catalytic triad, has rotated approximately 180 degrees around the Cbeta-Cgamma bond. Two new water molecules in the active site stabilize the rotated conformation. This rotation places His64 in an unfavorable geometry to interact with the other members of the catalytic triad, Ser221 and Asp32. NMR experiments confirm that the characteristic resonance due to the low barrier hydrogen bond between the His64 and Asp32 is absent in 50% DMF. These experiments provide a clear structural basis for the change in activity of serine proteases in organic co-solvents.  (+info)

His ... Asp catalytic dyad of ribonuclease A: histidine pKa values in the wild-type, D121N, and D121A enzymes. (5/5209)

Bovine pancreatic ribonuclease A (RNase A) has a conserved His ... Asp catalytic dyad in its active site. Structural analyses had indicated that Asp121 forms a hydrogen bond with His119, which serves as an acid during catalysis of RNA cleavage. The enzyme contains three other histidine residues including His12, which is also in the active site. Here, 1H-NMR spectra of wild-type RNase A and the D121N and D121A variants were analyzed thoroughly as a function of pH. The effect of replacing Asp121 on the microscopic pKa values of the histidine residues is modest: none change by more than 0.2 units. There is no evidence for the formation of a low-barrier hydrogen bond between His119 and either an aspartate or an asparagine residue at position 121. In the presence of the reaction product, uridine 3'-phosphate (3'-UMP), protonation of one active-site histidine residue favors protonation of the other. This finding is consistent with the phosphoryl group of 3'-UMP interacting more strongly with the two active-site histidine residues when both are protonated. Comparison of the titration curves of the unliganded enzyme with that obtained in the presence of different concentrations of 3'-UMP shows that a second molecule of 3'-UMP can bind to the enzyme. Together, the data indicate that the aspartate residue in the His ... Asp catalytic dyad of RNase A has a measurable but modest effect on the ionization of the adjacent histidine residue.  (+info)

Mutational analysis of Bacillus subtilis glutamine phosphoribosylpyrophosphate amidotransferase propeptide processing. (6/5209)

Glutamine phosphoribosylpyrophosphate amidotransferase from Bacillus subtilis is a member of an N-terminal nucleophile hydrolase enzyme superfamily, several of which undergo autocatalytic propeptide processing to generate the mature active enzyme. A series of mutations was analyzed to determine whether amino acid residues required for catalysis are also used for propeptide processing. Propeptide cleavage was strongly inhibited by replacement of the cysteine nucleophile and two residues of an oxyanion hole that are required for glutaminase function. However, significant propeptide processing was retained in a deletion mutant with multiple defects in catalysis that was devoid of enzyme activity. Intermolecular processing of noncleaved mutant enzyme subunits by active wild-type enzyme subunits was not detected in hetero-oligomers obtained from a coexpression experiment. While direct in vitro evidence for autocatalytic propeptide cleavage was not obtained, the results indicate that some but not all of the amino acid residues that have a role in catalysis are also needed for propeptide processing.  (+info)

Metal-catalyzed oxidation of phenylalanine-sensitive 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase from Escherichia coli: inactivation and destabilization by oxidation of active-site cysteines. (7/5209)

The in vitro instability of the phenylalanine-sensitive 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase [DAHPS(Phe)] from Escherichia coli has been found to be due to a metal-catalyzed oxidation mechanism. DAHPS(Phe) is one of three differentially feedback-regulated isoforms of the enzyme which catalyzes the first step of aromatic biosynthesis, the formation of DAHP from phosphoenolpyruvate and D-erythrose-4-phosphate. The activity of the apoenzyme decayed exponentially, with a half-life of about 1 day at room temperature, and the heterotetramer slowly dissociated to the monomeric state. The enzyme was stabilized by the presence of phosphoenolpyruvate or EDTA, indicating that in the absence of substrate, a trace metal(s) was the inactivating agent. Cu2+ and Fe2+, but none of the other divalent metals that activate the enzyme, greatly accelerated the rate of inactivation and subunit dissociation. Both anaerobiosis and the addition of catalase significantly reduced Cu2+-catalyzed inactivation. In the spontaneously inactivated enzyme, there was a net loss of two of the seven thiols per subunit; this value increased with increasing concentrations of added Cu2+. Dithiothreitol completely restored the enzymatic activity and the two lost thiols in the spontaneously inactivated enzyme but was only partially effective in reactivation of the Cu2+-inactivated enzyme. Mutant enzymes with conservative replacements at either of the two active-site cysteines, Cys61 or Cys328, were insensitive to the metal attack. Peptide mapping of the Cu2+-inactivated enzyme revealed a disulfide linkage between these two cysteine residues. All results indicate that DAHPS(Phe) is a metal-catalyzed oxidation system wherein bound substrate protects active-site residues from oxidative attack catalyzed by bound redox metal cofactor. A mechanism of inactivation of DAHPS is proposed that features a metal redox cycle that requires the sequential oxidation of its two active-site cysteines.  (+info)

Evidence for the head domain movement of the rieske iron-sulfur protein in electron transfer reaction of the cytochrome bc1 complex. (8/5209)

The three-dimensional structure of the mitochondrial cytochrome bc1 complex suggests that movement of the extramembrane domain (head) of the Rieske iron-sulfur protein (ISP) may play an important role in electron transfer. Such movement requires flexibility in the neck region of ISP, since the head and transmembrane domains of the protein are rather rigid. To test this hypothesis, Rhodobacter sphaeroides mutants expressing His-tagged cytochrome bc1 complexes with cysteine substitution at various positions in the ISP neck (residues 39-48) were generated and characterized. The mutants with a single cysteine substitution at Ala42 or Val44 and a double cysteine substitution at Val44 and Ala46 (VQA-CQC) or at Ala42 and Ala46 (ADVQA-CDVQC) have photosynthetic growth rates comparable with that of complement cells. Chromatophore membrane and intracytoplasmic membrane (ICM) prepared from these mutants have cytochrome bc1 complex activity similar to that in the complement membranes, indicating that flexibility of the neck region of ISP was not affected by these cysteine substitutions. Mutants with a double cysteine substitution at Ala42 and Val44 (ADV-CDC) or at Pro40 and Ala42 (PSA-CSC) have a retarded (50%) or no photosynthetic growth rate, respectively. The ADV-CDC or PSA-CSC mutant ICM contains 20 or 0% of the cytochrome bc1 complex activity found in the complement ICM. However, activity can be restored by the treatment with beta-mercaptoethanol (beta-ME). The restored activity is diminished upon removal of beta-ME but is retained if the beta-ME-treated membrane is treated with the sulfhydryl reagent N-ethylmaleimide or p-chloromercuribenzoic acid. These results indicate that the loss of bc1 complex activity in the ADV-CDC or PSA-CSC mutant membranes is due to disulfide bond formation, which increases the rigidity of ISP neck and, in turn, decreases the mobility of the head domain. Using the conditions developed for the isolation of His-tagged complement cytochrome bc1 complex, a two-subunit complex (cytochromes b and c1) is obtained from all of the double cysteine-substituted mutants. This suggests that introduction of two cysteines in the neck region of ISP weakens the interactions between cytochromes b, ISP, and subunit IV.  (+info)

Histidine is an essential amino acid, meaning it cannot be synthesized by the human body and must be obtained through dietary sources. Its chemical formula is C6H9N3O2. Histidine plays a crucial role in several physiological processes, including:

1. Protein synthesis: As an essential amino acid, histidine is required for the production of proteins, which are vital components of various tissues and organs in the body.

2. Hemoglobin synthesis: Histidine is a key component of hemoglobin, the protein in red blood cells responsible for carrying oxygen throughout the body. The imidazole side chain of histidine acts as a proton acceptor/donor, facilitating the release and uptake of oxygen by hemoglobin.

3. Acid-base balance: Histidine is involved in maintaining acid-base homeostasis through its role in the biosynthesis of histamine, which is a critical mediator of inflammatory responses and allergies. The decarboxylation of histidine results in the formation of histamine, which can increase vascular permeability and modulate immune responses.

4. Metal ion binding: Histidine has a high affinity for metal ions such as zinc, copper, and iron. This property allows histidine to participate in various enzymatic reactions and maintain the structural integrity of proteins.

5. Antioxidant defense: Histidine-containing dipeptides, like carnosine and anserine, have been shown to exhibit antioxidant properties by scavenging reactive oxygen species (ROS) and chelating metal ions. These compounds may contribute to the protection of proteins and DNA from oxidative damage.

Dietary sources of histidine include meat, poultry, fish, dairy products, and wheat germ. Histidine deficiency is rare but can lead to growth retardation, anemia, and impaired immune function.

Histidine Decarboxylase is a medical term that refers to an enzyme found in various organisms, including humans. This enzyme plays a crucial role in the conversion of the amino acid L-histidine into histamine, which is a biogenic amine that acts as a neurotransmitter and inflammatory mediator in the human body.

Histidine decarboxylase is found in several tissues, including the central nervous system, gastrointestinal tract, and skin. It requires pyridoxal 5'-phosphate (PLP) as a cofactor for its enzymatic activity. Abnormal levels or activity of histidine decarboxylase have been implicated in several medical conditions, including allergic reactions, inflammation, and neuropsychiatric disorders.

Inhibitors of histidine decarboxylase are being investigated as potential therapeutic agents for the treatment of various diseases, such as mast cell-mediated disorders, gastrointestinal disorders, and neurological conditions associated with abnormal histamine levels.

Diethyl pyrocarbonate (DEPC) is a chemical compound with the formula (C2H5O)2CO. It is a colorless, volatile liquid that is used as a disinfectant and sterilizing agent, particularly for laboratory equipment and solutions. DEPC works by reacting with amino groups in proteins, forming covalent bonds that inactivate enzymes and other proteins. This makes it effective at destroying bacteria, viruses, and spores.

However, DEPC is also reactive with nucleic acids, including DNA and RNA, so it must be removed or deactivated before using solutions treated with DEPC for molecular biology experiments. DEPC can be deactivated by heating the solution to 60-70°C for 30 minutes to an hour, which causes it to hydrolyze into ethanol and carbon dioxide.

It is important to handle DEPC with care, as it can cause irritation to the skin, eyes, and respiratory tract. It should be used in a well-ventilated area or under a fume hood, and protective clothing, gloves, and eye/face protection should be worn when handling the chemical.

Histidine Ammonia-Lyase (HAL) is an enzyme that catalyzes the conversion of the amino acid L-histidine into trans-urocanic acid, ammonia, and water. This reaction is a part of the histidine catabolism pathway in many organisms, including humans. The enzyme accomplishes this transformation by removing an ammonia group from the imidazole ring of L-histidine, resulting in the formation of trans-urocanic acid. Histidine Ammonia-Lyase plays a crucial role in histidine metabolism and has been studied for its potential implications in various physiological processes and diseases.

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.

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.

Hydrogen-ion concentration, also known as pH, is a measure of the acidity or basicity of a solution. It is defined as the negative logarithm (to the base 10) of the hydrogen ion activity in a solution. The standard unit of measurement is the pH unit. A pH of 7 is neutral, less than 7 is acidic, and greater than 7 is basic.

In medical terms, hydrogen-ion concentration is important for maintaining homeostasis within the body. For example, in the stomach, a high hydrogen-ion concentration (low pH) is necessary for the digestion of food. However, in other parts of the body such as blood, a high hydrogen-ion concentration can be harmful and lead to acidosis. Conversely, a low hydrogen-ion concentration (high pH) in the blood can lead to alkalosis. Both acidosis and alkalosis can have serious consequences on various organ systems if not corrected.

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.

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.

ATP phosphoribosyltransferase (ATP-PRT, or adenine phosphoribosyltransferase) is an enzyme involved in the purine nucleotide biosynthesis pathway. The enzyme catalyzes the conversion of ATP and 5-phosphoribosyl-1-pyrophosphate (PRPP) to adenosine monophosphate (AMP) and pyrophosphate (PPi). This reaction is part of the salvage pathway, which recycles purines by converting free purine bases back into nucleotides. A deficiency in ATP-PRT can lead to a rare genetic disorder known as adenine phosphoribosyltransferase deficiency or APRT deficiency, which is characterized by the accumulation of 2,8-dihydroxyadenine crystals in the renal tubules, resulting in kidney stones and potential kidney damage.

Histidinol is not typically considered a medical term, but it is a biochemical concept. Histidinol is an intermediate in the metabolic pathway for the synthesis of the amino acid histidine. It is a reduced form of histidine, where a hydroxyl group replaces the imidazole ring's double-bonded nitrogen atom.

In clinical or medical contexts, Histidinol may be mentioned in relation to inborn errors of metabolism, such as histidinemia, which is characterized by an accumulation of histidine and its metabolites, including histidinol, due to a deficiency in the enzyme histidase. However, it's worth noting that histidinemia is typically asymptomatic or associated with mild symptoms, such as delayed development, learning difficulties, or speech problems.

Urocanate hydratase is an enzyme that is involved in the metabolism of the amino acid histidine. The gene for this enzyme is located on chromosome 7q31-q32. Urocanate hydratase catalyzes the conversion of urocanate to imidazoleacetic acid, which is an important step in the degradation of histidine. Defects in this enzyme can lead to a rare genetic disorder called histidinemia, which is characterized by elevated levels of histidine and its metabolites in the blood and urine. However, it's important to note that histidinemia is generally considered a benign condition, and affected individuals usually do not experience any symptoms or complications.

Protein kinases are a group of enzymes that play a crucial role in many cellular processes by adding phosphate groups to other proteins, a process known as phosphorylation. This modification can activate or deactivate the target protein's function, thereby regulating various signaling pathways within the cell. Protein kinases are essential for numerous biological functions, including metabolism, signal transduction, cell cycle progression, and apoptosis (programmed cell death). Abnormal regulation of protein kinases has been implicated in several diseases, such as cancer, diabetes, and neurological disorders.

Amino acids are organic compounds that serve as the building blocks of proteins. They consist of a central carbon atom, also known as the alpha carbon, which is bonded to an amino group (-NH2), a carboxyl group (-COOH), a hydrogen atom (H), and a variable side chain (R group). The R group can be composed of various combinations of atoms such as hydrogen, oxygen, sulfur, nitrogen, and carbon, which determine the unique properties of each amino acid.

There are 20 standard amino acids that are encoded by the genetic code and incorporated into proteins during translation. These include:

1. Alanine (Ala)
2. Arginine (Arg)
3. Asparagine (Asn)
4. Aspartic acid (Asp)
5. Cysteine (Cys)
6. Glutamine (Gln)
7. Glutamic acid (Glu)
8. Glycine (Gly)
9. Histidine (His)
10. Isoleucine (Ile)
11. Leucine (Leu)
12. Lysine (Lys)
13. Methionine (Met)
14. Phenylalanine (Phe)
15. Proline (Pro)
16. Serine (Ser)
17. Threonine (Thr)
18. Tryptophan (Trp)
19. Tyrosine (Tyr)
20. Valine (Val)

Additionally, there are several non-standard or modified amino acids that can be incorporated into proteins through post-translational modifications, such as hydroxylation, methylation, and phosphorylation. These modifications expand the functional diversity of proteins and play crucial roles in various cellular processes.

Amino acids are essential for numerous biological functions, including protein synthesis, enzyme catalysis, neurotransmitter production, energy metabolism, and immune response regulation. Some amino acids can be synthesized by the human body (non-essential), while others must be obtained through dietary sources (essential).

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.

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.

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.

'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.

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.

Acid anhydride hydrolases are a class of enzymes that catalyze the hydrolysis (breakdown) of acid anhydrides, which are chemical compounds formed by the reaction between two carboxylic acids. This reaction results in the formation of a molecule of water and the release of a new carboxylic acid.

Acid anhydride hydrolases play important roles in various biological processes, including the metabolism of lipids, carbohydrates, and amino acids. They are also involved in the regulation of intracellular pH and the detoxification of xenobiotics (foreign substances).

Examples of acid anhydride hydrolases include esterases, lipases, and phosphatases. These enzymes have different substrate specificities and catalytic mechanisms, but they all share the ability to hydrolyze acid anhydrides.

The term "acid anhydride hydrolase" is often used interchangeably with "esterase," although not all esterases are capable of hydrolyzing acid anhydrides.

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.

Zinc is an essential mineral that is vital for the functioning of over 300 enzymes and involved in various biological processes in the human body, including protein synthesis, DNA synthesis, immune function, wound healing, and cell division. It is a component of many proteins and participates in the maintenance of structural integrity and functionality of proteins. Zinc also plays a crucial role in maintaining the sense of taste and smell.

The recommended daily intake of zinc varies depending on age, sex, and life stage. Good dietary sources of zinc include red meat, poultry, seafood, beans, nuts, dairy products, and fortified cereals. Zinc deficiency can lead to various health problems, including impaired immune function, growth retardation, and developmental delays in children. On the other hand, excessive intake of zinc can also have adverse effects on health, such as nausea, vomiting, and impaired immune function.

I'm sorry for the confusion, but "Peptide PHI" is not a widely recognized or established medical term. It seems that there might be some misunderstanding or miscommunication related to this term.

If you are referring to a specific type of peptide or a research study, could you please provide more context or clarify the source of the term? I would be happy to help you with accurate and reliable information once I have a better understanding of what you are asking about.

Formiminoglutamic acid (FIGLU) is not a medical condition, but rather a substance that is involved in the metabolism of the amino acid histidine. It's a product of the degradation of histidine by the enzyme histidase. Formiminoglutamic acid then gets further metabolized to glutamic acid by the enzyme formiminotransferase, which requires folate as a cofactor.

An increased excretion of FIGLU in urine can be used as a functional test for folate deficiency or defects in folate metabolism. This is because if there is a lack of folate, the conversion of FIGLU to glutamic acid cannot occur, leading to an accumulation of FIGLU and its excretion in the urine.

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.

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.

Histamine is defined as a biogenic amine that is widely distributed throughout the body and is involved in various physiological functions. It is derived primarily from the amino acid histidine by the action of histidine decarboxylase. Histamine is stored in granules (along with heparin and proteases) within mast cells and basophils, and is released upon stimulation or degranulation of these cells.

Once released into the tissues and circulation, histamine exerts a wide range of pharmacological actions through its interaction with four types of G protein-coupled receptors (H1, H2, H3, and H4 receptors). Histamine's effects are diverse and include modulation of immune responses, contraction and relaxation of smooth muscle, increased vascular permeability, stimulation of gastric acid secretion, and regulation of neurotransmission.

Histamine is also a potent mediator of allergic reactions and inflammation, causing symptoms such as itching, sneezing, runny nose, and wheezing. Antihistamines are commonly used to block the actions of histamine at H1 receptors, providing relief from these symptoms.

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.

Heme is not a medical term per se, but it is a term used in the field of medicine and biology. Heme is a prosthetic group found in hemoproteins, which are proteins that contain a heme iron complex. This complex plays a crucial role in various biological processes, including oxygen transport (in hemoglobin), electron transfer (in cytochromes), and chemical catalysis (in peroxidases and catalases).

The heme group consists of an organic component called a porphyrin ring, which binds to a central iron atom. The iron atom can bind or release electrons, making it essential for redox reactions in the body. Heme is also vital for the formation of hemoglobin and myoglobin, proteins responsible for oxygen transport and storage in the blood and muscles, respectively.

In summary, heme is a complex organic-inorganic structure that plays a critical role in several biological processes, particularly in electron transfer and oxygen transport.

Carnosine is a dipeptide molecule composed of the amino acids histidine and alanine, which is naturally found in high concentrations in certain tissues of the body, particularly in muscle and brain tissue. It acts as an antioxidant, helping to protect cells from damage caused by free radicals and other oxidative stressors. Carnosine also has anti-glycation properties, meaning it helps prevent the formation of advanced glycation end products (AGEs) that can contribute to aging and age-related diseases. Additionally, carnosine has been shown to have potential benefits in neuroprotection, cardioprotection, and anti-inflammation. It is being studied for its potential therapeutic uses in various health conditions, including diabetes, cataracts, Alzheimer's disease, and other neurological disorders.

Methylhistidines are not a medical condition or disease, but rather refer to a group of biochemical compounds that are derived from the amino acid histidine. Specifically, methylhistidines are formed when histidine undergoes methylation, which is the addition of a methyl group (-CH3) to the histidine molecule.

There are three main types of methylhistidines that are commonly studied: 1-methylhistidine, 2-methylhistidine, and 3-methylhistidine. These compounds can be found in various tissues and fluids throughout the body, including muscles, urine, and cerebrospinal fluid.

In the medical field, methylhistidines are often used as markers of muscle breakdown and turnover. For example, increased levels of 1-methylhistidine in the urine have been associated with muscle wasting and other conditions that cause muscle damage or degeneration, such as muscular dystrophy and kidney disease. Similarly, elevated levels of 3-methylhistidine have been observed in patients with certain neuromuscular disorders, such as amyotrophic lateral sclerosis (ALS) and spinal muscular atrophy (SMA).

Overall, while methylhistidines are not a medical condition themselves, they can provide valuable insights into various physiological processes and disease states.

Magnetic Resonance Spectroscopy (MRS) is a non-invasive diagnostic technique that provides information about the biochemical composition of tissues, including their metabolic state. It is often used in conjunction with Magnetic Resonance Imaging (MRI) to analyze various metabolites within body tissues, such as the brain, heart, liver, and muscles.

During MRS, a strong magnetic field, radio waves, and a computer are used to produce detailed images and data about the concentration of specific metabolites in the targeted tissue or organ. This technique can help detect abnormalities related to energy metabolism, neurotransmitter levels, pH balance, and other biochemical processes, which can be useful for diagnosing and monitoring various medical conditions, including cancer, neurological disorders, and metabolic diseases.

There are different types of MRS, such as Proton (^1^H) MRS, Phosphorus-31 (^31^P) MRS, and Carbon-13 (^13^C) MRS, each focusing on specific elements or metabolites within the body. The choice of MRS technique depends on the clinical question being addressed and the type of information needed for diagnosis or monitoring purposes.

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.

Tertiary protein structure refers to the three-dimensional arrangement of all the elements (polypeptide chains) of a single protein molecule. It is the highest level of structural organization and results from interactions between various side chains (R groups) of the amino acids that make up the protein. These interactions, which include hydrogen bonds, ionic bonds, van der Waals forces, and disulfide bridges, give the protein its unique shape and stability, which in turn determines its function. The tertiary structure of a protein can be stabilized by various factors such as temperature, pH, and the presence of certain ions. Any changes in these factors can lead to denaturation, where the protein loses its tertiary structure and thus its function.

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.

I'm sorry for any confusion, but "Formates" is not a recognized term in medical terminology. It is possible that you may be referring to "formic acid" or "formate," which are terms used in chemistry and biochemistry. Formic acid is a colorless, pungent, and corrosive liquid with the chemical formula HCOOH. Its salts are called formates.

Formate is the anion (negatively charged ion) of formic acid, with the chemical formula HCOO-. Formate can be found in various biological systems and is involved in several metabolic processes. If you could provide more context or clarify your question, I would be happy to help further.

A Structure-Activity Relationship (SAR) in the context of medicinal chemistry and pharmacology refers to the relationship between the chemical structure of a drug or molecule and its biological activity or effect on a target protein, cell, or organism. SAR studies aim to identify patterns and correlations between structural features of a compound and its ability to interact with a specific biological target, leading to a desired therapeutic response or undesired side effects.

By analyzing the SAR, researchers can optimize the chemical structure of lead compounds to enhance their potency, selectivity, safety, and pharmacokinetic properties, ultimately guiding the design and development of novel drugs with improved efficacy and reduced toxicity.

Transfer RNA (tRNA) is a type of RNA molecule that plays a crucial role in protein synthesis. It carries amino acids to the ribosome, where they are incorporated into growing polypeptide chains during translation, the process by which the genetic code in mRNA is translated into a protein sequence.

tRNAs have a characteristic cloverleaf-like secondary structure and a stem-loop tertiary structure, which allows them to recognize specific codons on the mRNA through base-pairing between their anticodon loops and the complementary codons. Each tRNA is specific for one amino acid, and there are multiple tRNAs for each amino acid that differ in their anticodon sequences, allowing them to recognize different codons that specify the same amino acid.

"His" refers to the amino acid Histidine, which is encoded by the codons CAU and CAC on mRNA. Therefore, tRNA-His is a type of tRNA molecule that carries the amino acid Histidine to the ribosome during protein synthesis.

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.

Hydroxylamine is not a medical term, but it is a chemical compound with the formula NH2OH. It's used in some industrial processes and can also be found as a byproduct of certain metabolic reactions in the body. In a medical context, exposure to high levels of hydroxylamine may cause irritation to the skin, eyes, and respiratory tract, and it may have harmful effects on the nervous system and blood if ingested or absorbed in large amounts. However, it is not a substance that is commonly encountered or monitored in medical settings.

I believe there may be some confusion in your question. Whales are not a medical term but rather large marine mammals. They belong to the Cetacean family, which includes dolphins and porpoises. If you're asking about a medical condition or something similar that might be associated with the word "whales," I would need more information to provide an accurate response.

An amino acid substitution is a type of mutation in which one amino acid in a protein is replaced by another. This occurs when there is a change in the DNA sequence that codes for a particular amino acid in a protein. The genetic code is redundant, meaning that most amino acids are encoded by more than one codon (a sequence of three nucleotides). As a result, a single base pair change in the DNA sequence may not necessarily lead to an amino acid substitution. However, if a change does occur, it can have a variety of effects on the protein's structure and function, depending on the nature of the substituted amino acids. Some substitutions may be harmless, while others may alter the protein's activity or stability, leading to disease.

An operon is a genetic unit in prokaryotic organisms (like bacteria) consisting of a cluster of genes that are transcribed together as a single mRNA molecule, which then undergoes translation to produce multiple proteins. This genetic organization allows for the coordinated regulation of genes that are involved in the same metabolic pathway or functional process. The unit typically includes promoter and operator regions that control the transcription of the operon, as well as structural genes encoding the proteins. Operons were first discovered in bacteria, but similar genetic organizations have been found in some eukaryotic organisms, such as yeast.

In the context of medicine, particularly in relation to cancer treatment, protons refer to positively charged subatomic particles found in the nucleus of an atom. Proton therapy, a type of radiation therapy, uses a beam of protons to target and destroy cancer cells with high precision, minimizing damage to surrounding healthy tissue. The concentrated dose of radiation is delivered directly to the tumor site, reducing side effects and improving quality of life during treatment.

Copper is a chemical element with the symbol Cu (from Latin: *cuprum*) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. Copper is found as a free element in nature, and it is also a constituent of many minerals such as chalcopyrite and bornite.

In the human body, copper is an essential trace element that plays a role in various physiological processes, including iron metabolism, energy production, antioxidant defense, and connective tissue synthesis. Copper is found in a variety of foods, such as shellfish, nuts, seeds, whole grains, and organ meats. The recommended daily intake of copper for adults is 900 micrograms (mcg) per day.

Copper deficiency can lead to anemia, neutropenia, impaired immune function, and abnormal bone development. Copper toxicity, on the other hand, can cause nausea, vomiting, abdominal pain, diarrhea, and in severe cases, liver damage and neurological symptoms. Therefore, it is important to maintain a balanced copper intake through diet and supplements if necessary.

Myoglobin is a protein found in the muscle tissue, particularly in red or skeletal muscles. It belongs to the globin family and has a similar structure to hemoglobin, another oxygen-binding protein found in red blood cells. Myoglobin's primary function is to store oxygen within the muscle cells, making it readily available for use during periods of increased oxygen demand, such as during physical exertion.

Myoglobin contains heme groups that bind to and release oxygen molecules. The protein has a higher affinity for oxygen than hemoglobin, allowing it to maintain its bound oxygen even in low-oxygen environments. When muscle cells are damaged or undergo necrosis (cell death), myoglobin is released into the bloodstream and can be detected in serum or urine samples. Elevated levels of myoglobin in the blood or urine may indicate muscle injury, trauma, or diseases affecting muscle integrity, such as rhabdomyolysis or muscular dystrophies.

Cysteine is a semi-essential amino acid, which means that it can be produced by the human body under normal circumstances, but may need to be obtained from external sources in certain conditions such as illness or stress. Its chemical formula is HO2CCH(NH2)CH2SH, and it contains a sulfhydryl group (-SH), which allows it to act as a powerful antioxidant and participate in various cellular processes.

Cysteine plays important roles in protein structure and function, detoxification, and the synthesis of other molecules such as glutathione, taurine, and coenzyme A. It is also involved in wound healing, immune response, and the maintenance of healthy skin, hair, and nails.

Cysteine can be found in a variety of foods, including meat, poultry, fish, dairy products, eggs, legumes, nuts, seeds, and some grains. It is also available as a dietary supplement and can be used in the treatment of various medical conditions such as liver disease, bronchitis, and heavy metal toxicity. However, excessive intake of cysteine may have adverse effects on health, including gastrointestinal disturbances, nausea, vomiting, and headaches.

Heme proteins are a type of protein that contain a heme group, which is a prosthetic group composed of an iron atom contained in the center of a large organic ring called a porphyrin. The heme group gives these proteins their characteristic red color. Hemeproteins have various important functions in biological systems, including oxygen transport (e.g., hemoglobin), electron transfer (e.g., cytochromes), and enzymatic catalysis (e.g., peroxidases and catalases). The heme group can bind and release gases, such as oxygen and carbon monoxide, and can participate in redox reactions due to the ease with which iron can change its oxidation state.

"Salmonella enterica" serovar "Typhimurium" is a subspecies of the bacterial species Salmonella enterica, which is a gram-negative, facultatively anaerobic, rod-shaped bacterium. It is a common cause of foodborne illness in humans and animals worldwide. The bacteria can be found in a variety of sources, including contaminated food and water, raw meat, poultry, eggs, and dairy products.

The infection caused by Salmonella Typhimurium is typically self-limiting and results in gastroenteritis, which is characterized by symptoms such as diarrhea, abdominal cramps, fever, and vomiting. However, in some cases, the infection can spread to other parts of the body and cause more severe illness, particularly in young children, older adults, and people with weakened immune systems.

Salmonella Typhimurium is a major public health concern due to its ability to cause outbreaks of foodborne illness, as well as its potential to develop antibiotic resistance. Proper food handling, preparation, and storage practices can help prevent the spread of Salmonella Typhimurium and other foodborne pathogens.

Gene expression regulation in bacteria refers to the complex cellular processes that control the production of proteins from specific genes. This regulation allows bacteria to adapt to changing environmental conditions and ensure the appropriate amount of protein is produced at the right time.

Bacteria have a variety of mechanisms for regulating gene expression, including:

1. Operon structure: Many bacterial genes are organized into operons, which are clusters of genes that are transcribed together as a single mRNA molecule. The expression of these genes can be coordinately regulated by controlling the transcription of the entire operon.
2. Promoter regulation: Transcription is initiated at promoter regions upstream of the gene or operon. Bacteria have regulatory proteins called sigma factors that bind to the promoter and recruit RNA polymerase, the enzyme responsible for transcribing DNA into RNA. The binding of sigma factors can be influenced by environmental signals, allowing for regulation of transcription.
3. Attenuation: Some operons have regulatory regions called attenuators that control transcription termination. These regions contain hairpin structures that can form in the mRNA and cause transcription to stop prematurely. The formation of these hairpins is influenced by the concentration of specific metabolites, allowing for regulation of gene expression based on the availability of those metabolites.
4. Riboswitches: Some bacterial mRNAs contain regulatory elements called riboswitches that bind small molecules directly. When a small molecule binds to the riboswitch, it changes conformation and affects transcription or translation of the associated gene.
5. CRISPR-Cas systems: Bacteria use CRISPR-Cas systems for adaptive immunity against viruses and plasmids. These systems incorporate short sequences from foreign DNA into their own genome, which can then be used to recognize and cleave similar sequences in invading genetic elements.

Overall, gene expression regulation in bacteria is a complex process that allows them to respond quickly and efficiently to changing environmental conditions. Understanding these regulatory mechanisms can provide insights into bacterial physiology and help inform strategies for controlling bacterial growth and behavior.

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.

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.

Aspartic acid is an α-amino acid with the chemical formula HO2CCH(NH2)CO2H. It is one of the twenty standard amino acids, and it is a polar, negatively charged, and hydrophilic amino acid. In proteins, aspartic acid usually occurs in its ionized form, aspartate, which has a single negative charge.

Aspartic acid plays important roles in various biological processes, including metabolism, neurotransmitter synthesis, and energy production. It is also a key component of many enzymes and proteins, where it often contributes to the formation of ionic bonds and helps stabilize protein structure.

In addition to its role as a building block of proteins, aspartic acid is also used in the synthesis of other important biological molecules, such as nucleotides, which are the building blocks of DNA and RNA. It is also a component of the dipeptide aspartame, an artificial sweetener that is widely used in food and beverages.

Like other amino acids, aspartic acid is essential for human health, but it cannot be synthesized by the body and must be obtained through the diet. Foods that are rich in aspartic acid include meat, poultry, fish, dairy products, eggs, legumes, and some fruits and vegetables.

Rose Bengal is not a medical term per se, but a chemical compound that is used in various medical applications. It's a dye that is primarily used as a diagnostic stain to test for damaged or denatured cells, particularly in the eye and mouth. In ophthalmology, a Rose Bengal stain is used to identify damage to the cornea's surface, while in dentistry, it can help detect injured oral mucosa or lesions.

The dye works by staining dead or damaged cells more intensely than healthy ones, allowing healthcare professionals to visualize and assess any abnormalities or injuries. However, it is important to note that Rose Bengal itself is not a treatment for these conditions; rather, it is a diagnostic tool used to inform appropriate medical interventions.

Histidine-tRNA ligase is an enzyme involved in the process of protein synthesis, specifically during the step of translation. Its primary function is to catalyze the attachment of the amino acid histidine to its corresponding transfer RNA (tRNA) molecule. This enzyme does this by forming a ester bond between the carboxyl group of histidine and the 3'-hydroxyl group of the tRNA, creating a charged histidine-tRNA complex.

The histidine-tRNA ligase enzyme plays a crucial role in maintaining the accuracy of protein synthesis, as it ensures that only the correct amino acid is attached to its specific tRNA. This helps to prevent errors in the genetic code and contributes to the proper folding and functioning of proteins.

The systematic name for this enzyme is "histidine:tRNA(His) ligase (AMP-forming)" and it belongs to the family of ligases, specifically the aminoacyl-tRNA ligases. The gene that encodes this enzyme in humans is known as HARS1 (Histidyl-tRNA Synthetase 1). Defects or mutations in this gene can lead to various genetic disorders, such as histidinemia and Charcot-Marie-Tooth disease.

Carboxy-lyases are a class of enzymes that catalyze the removal of a carboxyl group from a substrate, often releasing carbon dioxide in the process. These enzymes play important roles in various metabolic pathways, such as the biosynthesis and degradation of amino acids, sugars, and other organic compounds.

Carboxy-lyases are classified under EC number 4.2 in the Enzyme Commission (EC) system. They can be further divided into several subclasses based on their specific mechanisms and substrates. For example, some carboxy-lyases require a cofactor such as biotin or thiamine pyrophosphate to facilitate the decarboxylation reaction, while others do not.

Examples of carboxy-lyases include:

1. Pyruvate decarboxylase: This enzyme catalyzes the conversion of pyruvate to acetaldehyde and carbon dioxide during fermentation in yeast and other organisms.
2. Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO): This enzyme is essential for photosynthesis in plants and some bacteria, as it catalyzes the fixation of carbon dioxide into an organic molecule during the Calvin cycle.
3. Phosphoenolpyruvate carboxylase: Found in plants, algae, and some bacteria, this enzyme plays a role in anaplerotic reactions that replenish intermediates in the citric acid cycle. It catalyzes the conversion of phosphoenolpyruvate to oxaloacetate and inorganic phosphate.
4. Aspartate transcarbamylase: This enzyme is involved in the biosynthesis of pyrimidines, a class of nucleotides. It catalyzes the transfer of a carboxyl group from carbamoyl aspartate to carbamoyl phosphate, forming cytidine triphosphate (CTP) and fumarate.
5. Urocanase: Found in animals, this enzyme is involved in histidine catabolism. It catalyzes the conversion of urocanate to formiminoglutamate and ammonia.

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.

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.

Secondary protein structure refers to the local spatial arrangement of amino acid chains in a protein, typically described as regular repeating patterns held together by hydrogen bonds. The two most common types of secondary structures are the alpha-helix (α-helix) and the beta-pleated sheet (β-sheet). In an α-helix, the polypeptide chain twists around itself in a helical shape, with each backbone atom forming a hydrogen bond with the fourth amino acid residue along the chain. This forms a rigid rod-like structure that is resistant to bending or twisting forces. In β-sheets, adjacent segments of the polypeptide chain run parallel or antiparallel to each other and are connected by hydrogen bonds, forming a pleated sheet-like arrangement. These secondary structures provide the foundation for the formation of tertiary and quaternary protein structures, which determine the overall three-dimensional shape and function of the protein.

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.

Ammonia-lyases are a class of enzymes that catalyze the removal of an amino group from a substrate, releasing ammonia in the process. These enzymes play important roles in various biological pathways, including the biosynthesis and degradation of various metabolites such as amino acids, carbohydrates, and aromatic compounds.

The reaction catalyzed by ammonia-lyases typically involves the conversion of an alkyl or aryl group to a carbon-carbon double bond through the elimination of an amine group. This reaction is often reversible, allowing the enzyme to also catalyze the addition of an amino group to a double bond.

Ammonia-lyases are classified based on the type of substrate they act upon and the mechanism of the reaction they catalyze. Some examples of ammonia-lyases include aspartate ammonia-lyase, which catalyzes the conversion of aspartate to fumarate, and tyrosine ammonia-lyase, which converts tyrosine to p-coumaric acid.

These enzymes are important in both plant and animal metabolism and have potential applications in biotechnology and industrial processes.

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.

Hydroxylamines are organic compounds that contain a hydroxy group (-OH) and an amino group (-NH2) in their structure. More specifically, they have the functional group R-N-OH, where R represents a carbon-containing radical. Hydroxylamines can be considered as derivatives of ammonia (NH3), where one hydrogen atom is replaced by a hydroxy group.

These compounds are important in organic chemistry and biochemistry due to their ability to act as reducing agents, nitrogen donors, and intermediates in various chemical reactions. They can be found in some natural substances and are also synthesized for use in pharmaceuticals, agrochemicals, and other industrial applications.

Examples of hydroxylamines include:

* Hydroxylamine (NH2OH) itself, which is a colorless liquid at room temperature with an odor similar to ammonia.
* N-Methylhydroxylamine (CH3NHOH), which is a solid that can be used as a reducing agent and a nucleophile in organic synthesis.
* Phenylhydroxylamine (C6H5NHOH), which is a solid used as an intermediate in the production of dyes, pharmaceuticals, and other chemicals.

It's important to note that hydroxylamines can be unstable and potentially hazardous, so they should be handled with care during laboratory work or industrial processes.

Spectrum analysis in the context of Raman spectroscopy refers to the measurement and interpretation of the Raman scattering spectrum of a material or sample. Raman spectroscopy is a non-destructive analytical technique that uses the inelastic scattering of light to examine the vibrational modes of molecules.

When a monochromatic light source, typically a laser, illuminates a sample, a small fraction of the scattered light undergoes a shift in frequency due to interactions with the molecular vibrations of the sample. This shift in frequency is known as the Raman shift and is unique to each chemical bond or functional group within a molecule.

In a Raman spectrum, the intensity of the scattered light is plotted against the Raman shift, which is expressed in wavenumbers (cm-1). The resulting spectrum provides a "fingerprint" of the sample's molecular structure and composition, allowing for the identification and characterization of various chemical components within the sample.

Spectrum analysis in Raman spectroscopy can reveal valuable information about the sample's crystallinity, phase transitions, polymorphism, molecular orientation, and other properties. This technique is widely used across various fields, including materials science, chemistry, biology, pharmaceuticals, and forensics, to analyze a diverse range of samples, from simple liquids and solids to complex biological tissues and nanomaterials.

Histidinol-Phosphatase is not a widely recognized medical term, but it is a term used in biochemistry and molecular biology. It refers to an enzyme that catalyzes the dephosphorylation of histidinol phosphate to form histidinol during the biosynthesis of the amino acid histidine.

The medical relevance of this enzyme is related to genetic disorders affecting the metabolic pathway of histidine synthesis, such as histidinemia, which can result from deficiencies in the activity of this enzyme or other enzymes involved in the histidine biosynthetic pathway. However, it's important to note that a specific medical definition for 'Histidinol-Phosphatase' is not commonly used.

Alanine is an alpha-amino acid that is used in the biosynthesis of proteins. The molecular formula for alanine is C3H7NO2. It is a non-essential amino acid, which means that it can be produced by the human body through the conversion of other nutrients, such as pyruvate, and does not need to be obtained directly from the diet.

Alanine is classified as an aliphatic amino acid because it contains a simple carbon side chain. It is also a non-polar amino acid, which means that it is hydrophobic and tends to repel water. Alanine plays a role in the metabolism of glucose and helps to regulate blood sugar levels. It is also involved in the transfer of nitrogen between tissues and helps to maintain the balance of nitrogen in the body.

In addition to its role as a building block of proteins, alanine is also used as a neurotransmitter in the brain and has been shown to have a calming effect on the nervous system. It is found in many foods, including meats, poultry, fish, eggs, dairy products, and legumes.

A conserved sequence in the context of molecular biology refers to a pattern of nucleotides (in DNA or RNA) or amino acids (in proteins) that has remained relatively unchanged over evolutionary time. These sequences are often functionally important and are highly conserved across different species, indicating strong selection pressure against changes in these regions.

In the case of protein-coding genes, the corresponding amino acid sequence is deduced from the DNA sequence through the genetic code. Conserved sequences in proteins may indicate structurally or functionally important regions, such as active sites or binding sites, that are critical for the protein's activity. Similarly, conserved non-coding sequences in DNA may represent regulatory elements that control gene expression.

Identifying conserved sequences can be useful for inferring evolutionary relationships between species and for predicting the function of unknown genes or proteins.

Hydrogen bonding is not a medical term per se, but it is a fundamental concept in chemistry and biology that is relevant to the field of medicine. Here's a general definition:

Hydrogen bonding is a type of attractive force between molecules or within a molecule, which occurs when a hydrogen atom is bonded to a highly electronegative atom (like nitrogen, oxygen, or fluorine) and is then attracted to another electronegative atom. This attraction results in the formation of a partially covalent bond known as a "hydrogen bond."

In biological systems, hydrogen bonding plays a crucial role in the structure and function of many biomolecules, such as DNA, proteins, and carbohydrates. For example, the double helix structure of DNA is stabilized by hydrogen bonds between complementary base pairs (adenine-thymine and guanine-cytosine). Similarly, the three-dimensional structure of proteins is maintained by a network of hydrogen bonds that help to determine their function.

In medical contexts, hydrogen bonding can be relevant in understanding drug-receptor interactions, where hydrogen bonds between a drug molecule and its target protein can enhance the binding affinity and specificity of the interaction, leading to more effective therapeutic outcomes.

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.

A ligand, in the context of biochemistry and medicine, is a molecule that binds to a specific site on a protein or a larger biomolecule, such as an enzyme or a receptor. This binding interaction can modify the function or activity of the target protein, either activating it or inhibiting it. Ligands can be small molecules, like hormones or neurotransmitters, or larger structures, like antibodies. The study of ligand-protein interactions is crucial for understanding cellular processes and developing drugs, as many therapeutic compounds function by binding to specific targets within the body.

Arginine is an α-amino acid that is classified as a semi-essential or conditionally essential amino acid, depending on the developmental stage and health status of the individual. The adult human body can normally synthesize sufficient amounts of arginine to meet its needs, but there are certain circumstances, such as periods of rapid growth or injury, where the dietary intake of arginine may become necessary.

The chemical formula for arginine is C6H14N4O2. It has a molecular weight of 174.20 g/mol and a pKa value of 12.48. Arginine is a basic amino acid, which means that it contains a side chain with a positive charge at physiological pH levels. The side chain of arginine is composed of a guanidino group, which is a functional group consisting of a nitrogen atom bonded to three methyl groups.

In the body, arginine plays several important roles. It is a precursor for the synthesis of nitric oxide, a molecule that helps regulate blood flow and immune function. Arginine is also involved in the detoxification of ammonia, a waste product produced by the breakdown of proteins. Additionally, arginine can be converted into other amino acids, such as ornithine and citrulline, which are involved in various metabolic processes.

Foods that are good sources of arginine include meat, poultry, fish, dairy products, nuts, seeds, and legumes. Arginine supplements are available and may be used for a variety of purposes, such as improving exercise performance, enhancing wound healing, and boosting immune function. However, it is important to consult with a healthcare provider before taking arginine supplements, as they can interact with certain medications and have potential side effects.

I'm sorry for any confusion, but "Nickel" is not a medical term. It is a chemical element with the symbol Ni and atomic number 28. Nickel is a hard, silvery-white lustrous metal with a slight golden tinge. It is one of four elements that are ferromagnetic and is used as a common component in various alloys due to its properties such as resistance to corrosion and heat.

However, in a medical context, nickel may refer to:

* Nickel allergy: A type of allergic contact dermatitis caused by an immune system response to the presence of nickel in jewelry, clothing fasteners, or other items that come into contact with the skin. Symptoms can include redness, itching, and rash at the site of exposure.
* Nickel carbonyl: A highly toxic chemical compound (Ni(CO)4) that can cause respiratory and neurological problems if inhaled. It is produced during some industrial processes involving nickel and carbon monoxide and poses a health risk to workers if proper safety measures are not taken.

If you have any concerns about exposure to nickel or symptoms related to nickel allergy, it's best to consult with a healthcare professional for further evaluation and treatment.

'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.

Circular dichroism (CD) is a technique used in physics and chemistry to study the structure of molecules, particularly large biological molecules such as proteins and nucleic acids. It measures the difference in absorption of left-handed and right-handed circularly polarized light by a sample. This difference in absorption can provide information about the three-dimensional structure of the molecule, including its chirality or "handedness."

In more technical terms, CD is a form of spectroscopy that measures the differential absorption of left and right circularly polarized light as a function of wavelength. The CD signal is measured in units of millidegrees (mdeg) and can be positive or negative, depending on the type of chromophore and its orientation within the molecule.

CD spectra can provide valuable information about the secondary and tertiary structure of proteins, as well as the conformation of nucleic acids. For example, alpha-helical proteins typically exhibit a strong positive band near 190 nm and two negative bands at around 208 nm and 222 nm, while beta-sheet proteins show a strong positive band near 195 nm and two negative bands at around 217 nm and 175 nm.

CD spectroscopy is a powerful tool for studying the structural changes that occur in biological molecules under different conditions, such as temperature, pH, or the presence of ligands or other molecules. It can also be used to monitor the folding and unfolding of proteins, as well as the binding of drugs or other small molecules to their targets.

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.

Amino acid transport systems are specialized cellular mechanisms responsible for the active transport of amino acids across cell membranes. These systems are essential for maintaining proper amino acid homeostasis within cells and organisms. They consist of several types of transporters that can be categorized based on their energy source, electrochemical gradient, substrate specificity, and functional characteristics.

The term 'basic' in this context typically refers to the fundamental understanding of these transport systems, including their structure, function, regulation, and physiological roles. Amino acid transport systems play a crucial role in various biological processes, such as protein synthesis, neurotransmission, cell signaling, and energy metabolism.

There are two primary types of amino acid transport systems:

1. **Na+-dependent transporters:** These transporters utilize the sodium gradient across the cell membrane to drive the uptake of amino acids. They can be further divided into subtypes based on their substrate specificity and functional properties, such as system A, system ASC, system B0, system B, system L, and system y+.
2. **Na+-independent transporters:** These transporters do not rely on the sodium gradient for amino acid transport. Instead, they use other energy sources like proton gradients or direct coupling to membrane potential. Examples of Na+-independent transporters include system L, system y+, and system x-AG.

Understanding the basic aspects of amino acid transport systems is essential for elucidating their roles in health and disease. Dysregulation of these systems has been implicated in various pathological conditions, such as neurological disorders, cancer, and metabolic diseases.

Lysine is an essential amino acid, which means that it cannot be synthesized by the human body and must be obtained through the diet. Its chemical formula is (2S)-2,6-diaminohexanoic acid. Lysine is necessary for the growth and maintenance of tissues in the body, and it plays a crucial role in the production of enzymes, hormones, and antibodies. It is also essential for the absorption of calcium and the formation of collagen, which is an important component of bones and connective tissue. Foods that are good sources of lysine include meat, poultry, fish, eggs, and dairy products.

Tryptophan is an essential amino acid, meaning it cannot be synthesized by the human body and must be obtained through dietary sources. Its chemical formula is C11H12N2O2. Tryptophan plays a crucial role in various biological processes as it serves as a precursor to several important molecules, including serotonin, melatonin, and niacin (vitamin B3). Serotonin is a neurotransmitter involved in mood regulation, appetite control, and sleep-wake cycles, while melatonin is a hormone that regulates sleep-wake patterns. Niacin is essential for energy production and DNA repair.

Foods rich in tryptophan include turkey, chicken, fish, eggs, cheese, milk, nuts, seeds, and whole grains. In some cases, tryptophan supplementation may be recommended to help manage conditions related to serotonin imbalances, such as depression or insomnia, but this should only be done under the guidance of a healthcare professional due to potential side effects and interactions with other medications.

Spectrophotometry, Ultraviolet (UV-Vis) is a type of spectrophotometry that measures how much ultraviolet (UV) and visible light is absorbed or transmitted by a sample. It uses a device called a spectrophotometer to measure the intensity of light at different wavelengths as it passes through a sample. The resulting data can be used to determine the concentration of specific components within the sample, identify unknown substances, or evaluate the physical and chemical properties of materials.

UV-Vis spectroscopy is widely used in various fields such as chemistry, biology, pharmaceuticals, and environmental science. It can detect a wide range of substances including organic compounds, metal ions, proteins, nucleic acids, and dyes. The technique is non-destructive, meaning that the sample remains unchanged after the measurement.

In UV-Vis spectroscopy, the sample is placed in a cuvette or other container, and light from a source is directed through it. The light then passes through a monochromator, which separates it into its component wavelengths. The monochromatic light is then directed through the sample, and the intensity of the transmitted or absorbed light is measured by a detector.

The resulting absorption spectrum can provide information about the concentration and identity of the components in the sample. For example, if a compound has a known absorption maximum at a specific wavelength, its concentration can be determined by measuring the absorbance at that wavelength and comparing it to a standard curve.

Overall, UV-Vis spectrophotometry is a versatile and powerful analytical technique for quantitative and qualitative analysis of various samples in different fields.

A chemical model is a simplified representation or description of a chemical system, based on the laws of chemistry and physics. It is used to explain and predict the behavior of chemicals and chemical reactions. Chemical models can take many forms, including mathematical equations, diagrams, and computer simulations. They are often used in research, education, and industry to understand complex chemical processes and develop new products and technologies.

For example, a chemical model might be used to describe the way that atoms and molecules interact in a particular reaction, or to predict the properties of a new material. Chemical models can also be used to study the behavior of chemicals at the molecular level, such as how they bind to each other or how they are affected by changes in temperature or pressure.

It is important to note that chemical models are simplifications of reality and may not always accurately represent every aspect of a chemical system. They should be used with caution and validated against experimental data whenever possible.

Essential amino acids are a group of 9 out of the 20 standard amino acids that cannot be synthesized by the human body and must be obtained through diet. They include: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. These amino acids are essential for various biological processes such as protein synthesis, growth, and repair of body tissues. A deficiency in any of these essential amino acids can lead to impaired physical development and compromised immune function. Foods that provide all nine essential amino acids are considered complete proteins and include animal-derived products like meat, poultry, fish, eggs, and dairy, as well as soy and quinoa.

Nucleoside-diphosphate kinase (NDK) is an enzyme that plays a crucial role in the regulation of intracellular levels of nucleoside triphosphates and diphosphates. These nucleotides are essential for various cellular processes, including DNA replication, transcription, translation, and energy metabolism.

NDK catalyzes the transfer of a phosphate group from a nucleoside triphosphate (most commonly ATP or GTP) to a nucleoside diphosphate (NDP), converting it into a nucleoside triphosphate (NTP). The reaction can be summarized as follows:


The enzyme has several isoforms, which are differentially expressed in various tissues and cellular compartments. In humans, there are nine known isoforms of NDK, classified into three subfamilies: NM23-H (NME1), NM23-H2 (NME2), and NME4-8. These isoforms share a conserved catalytic core but differ in their regulatory domains and cellular localization.

NDK has been implicated in several physiological processes, such as cell proliferation, differentiation, and survival. Dysregulation of NDK activity has been associated with various pathological conditions, including cancer, neurodegenerative diseases, and viral infections.

The FIGLU (Formiminoglutamic acid excretion) test is not a medical definition itself, but it is a test used to help diagnose Phenylketonuria (PKU), an inherited disorder of amino acid metabolism.

In PKU, the body cannot break down the amino acid phenylalanine properly due to a deficiency in the enzyme phenylalanine hydroxylase. As a result, phenylalanine and its toxic byproducts accumulate in the body, which can cause brain damage and intellectual disability if left untreated.

The FIGLU test measures the amount of formiminoglutamic acid (FIGLU) in the urine after a patient is given a load of histidine, another amino acid. In people with PKU, the accumulation of phenylalanine inhibits the conversion of histidine to glutamic acid, leading to an increase in FIGLU excretion in the urine. Therefore, a positive FIGLU test can indicate the presence of PKU. However, it is not a definitive diagnostic test and should be confirmed with other tests such as plasma amino acid analysis and/or genetic testing.

Phosphorylation is the process of adding a phosphate group (a molecule consisting of one phosphorus atom and four oxygen atoms) to a protein or other organic molecule, which is usually done by enzymes called kinases. This post-translational modification can change the function, localization, or activity of the target molecule, playing a crucial role in various cellular processes such as signal transduction, metabolism, and regulation of gene expression. Phosphorylation is reversible, and the removal of the phosphate group is facilitated by enzymes called phosphatases.

'Caulobacter crescentus' is a gram-negative, oligotrophic aquatic bacterium that is commonly found in freshwater environments. It is known for its distinctive curved or "crescent" shape and the presence of a holdfast structure at one end, which allows it to attach to surfaces. 'Caulobacter crescentus' has a complex life cycle involving two distinct cell types: swarmer cells, which are motile and can swim in search of new surfaces to colonize, and stalked cells, which are non-motile and have a long, thin stalk that extends from the holdfast end. This bacterium is often used as a model organism for studying cell differentiation, asymmetric cell division, and the regulation of gene expression in response to environmental signals.

Phosphoric monoester hydrolases are a class of enzymes that catalyze the hydrolysis of phosphoric monoesters into alcohol and phosphate. This class of enzymes includes several specific enzymes, such as phosphatases and nucleotidases, which play important roles in various biological processes, including metabolism, signal transduction, and regulation of cellular processes.

Phosphoric monoester hydrolases are classified under the EC number 3.1.3 by the Nomenclature Committee of the International Union of Biochemistry and Molecular Biology (IUBMB). The enzymes in this class share a common mechanism of action, which involves the nucleophilic attack on the phosphorus atom of the substrate by a serine or cysteine residue in the active site of the enzyme. This results in the formation of a covalent intermediate, which is then hydrolyzed to release the products.

Phosphoric monoester hydrolases are important therapeutic targets for the development of drugs that can modulate their activity. For example, inhibitors of phosphoric monoester hydrolases have been developed as potential treatments for various diseases, including cancer, neurodegenerative disorders, and infectious diseases.

Signal transduction is the process by which a cell converts an extracellular signal, such as a hormone or neurotransmitter, into an intracellular response. This involves a series of molecular events that transmit the signal from the cell surface to the interior of the cell, ultimately resulting in changes in gene expression, protein activity, or metabolism.

The process typically begins with the binding of the extracellular signal to a receptor located on the cell membrane. This binding event activates the receptor, which then triggers a cascade of intracellular signaling molecules, such as second messengers, protein kinases, and ion channels. These molecules amplify and propagate the signal, ultimately leading to the activation or inhibition of specific cellular responses.

Signal transduction pathways are highly regulated and can be modulated by various factors, including other signaling molecules, post-translational modifications, and feedback mechanisms. Dysregulation of these pathways has been implicated in a variety of diseases, including cancer, diabetes, and neurological disorders.

Mutagenesis is the process by which the genetic material (DNA or RNA) of an organism is changed in a way that can alter its phenotype, or observable traits. These changes, known as mutations, can be caused by various factors such as chemicals, radiation, or viruses. Some mutations may have no effect on the organism, while others can cause harm, including diseases and cancer. Mutagenesis is a crucial area of study in genetics and molecular biology, with implications for understanding evolution, genetic disorders, and the development of new medical treatments.

A peptide fragment is a short chain of amino acids that is derived from a larger peptide or protein through various biological or chemical processes. These fragments can result from the natural breakdown of proteins in the body during regular physiological processes, such as digestion, or they can be produced experimentally in a laboratory setting for research or therapeutic purposes.

Peptide fragments are often used in research to map the structure and function of larger peptides and proteins, as well as to study their interactions with other molecules. In some cases, peptide fragments may also have biological activity of their own and can be developed into drugs or diagnostic tools. For example, certain peptide fragments derived from hormones or neurotransmitters may bind to receptors in the body and mimic or block the effects of the full-length molecule.

I'm sorry for any confusion, but "photochemistry" is not a term typically used in medical definitions. Photochemistry is a branch of chemistry that deals with the chemical effects of light. It involves the absorption of light by a substance, which can lead to the promotion of an electron to a higher energy state, and subsequently result in various chemical reactions.

In a medical context, photochemical processes might be discussed in relation to certain therapies or diagnostic techniques, such as photodynamic therapy for cancer treatment, where a photosensitizing agent is used that reacts with light to produce singlet oxygen or other reactive species to destroy nearby cells. However, it's not a term used to define a specific medical condition or concept in the same way that one might define "inflammation" or "metabolism."

Imidazoles are a class of heterocyclic organic compounds that contain a double-bonded nitrogen atom and two additional nitrogen atoms in the ring. They have the chemical formula C3H4N2. In a medical context, imidazoles are commonly used as antifungal agents. Some examples of imidazole-derived antifungals include clotrimazole, miconazole, and ketoconazole. These medications work by inhibiting the synthesis of ergosterol, a key component of fungal cell membranes, leading to increased permeability and death of the fungal cells. Imidazoles may also have anti-inflammatory, antibacterial, and anticancer properties.

A plasmid is a small, circular, double-stranded DNA molecule that is separate from the chromosomal DNA of a bacterium or other organism. Plasmids are typically not essential for the survival of the organism, but they can confer beneficial traits such as antibiotic resistance or the ability to degrade certain types of pollutants.

Plasmids are capable of replicating independently of the chromosomal DNA and can be transferred between bacteria through a process called conjugation. They often contain genes that provide resistance to antibiotics, heavy metals, and other environmental stressors. Plasmids have also been engineered for use in molecular biology as cloning vectors, allowing scientists to replicate and manipulate specific DNA sequences.

Plasmids are important tools in genetic engineering and biotechnology because they can be easily manipulated and transferred between organisms. They have been used to produce vaccines, diagnostic tests, and genetically modified organisms (GMOs) for various applications, including agriculture, medicine, and industry.

Anserine is a type of protein that belongs to the family of muscle proteins called myofibrillar proteins. It is found in high concentrations in the muscles of birds, especially in the breast muscle, and is also present in the muscles of some mammals, including humans. Anserine is composed of three peptide chains: two actin molecules and one tropomyosin molecule. It plays a role in the contraction and relaxation of muscles, and has been studied for its potential role in muscle function and disease. In humans, anserine is found primarily in type II (fast-twitch) muscle fibers, which are responsible for powerful, quick movements.

Phosphotransferases are a group of enzymes that catalyze the transfer of a phosphate group from a donor molecule to an acceptor molecule. This reaction is essential for various cellular processes, including energy metabolism, signal transduction, and biosynthesis.

The systematic name for this group of enzymes is phosphotransferase, which is derived from the general reaction they catalyze: D-donor + A-acceptor = D-donor minus phosphate + A-phosphate. The donor molecule can be a variety of compounds, such as ATP or a phosphorylated protein, while the acceptor molecule is typically a compound that becomes phosphorylated during the reaction.

Phosphotransferases are classified into several subgroups based on the type of donor and acceptor molecules they act upon. For example, kinases are a subgroup of phosphotransferases that transfer a phosphate group from ATP to a protein or other organic compound. Phosphatases, another subgroup, remove phosphate groups from molecules by transferring them to water.

Overall, phosphotransferases play a critical role in regulating many cellular functions and are important targets for drug development in various diseases, including cancer and neurological disorders.

Humans and other animals must ingest histidine or histidine-containing proteins. The biosynthesis of histidine has been widely ... In a histidine proton shuttle, histidine is used to quickly shuttle protons. It can do this by abstracting a proton with its ... For histidine, for adults 19 years and older, 14 mg/kg body weight/day. Supplemental histidine is being investigated for use in ... Histidine forms complexes with many metal ions. The imidazole sidechain of the histidine residue commonly serves as a ligand in ...
In terms of enzymology, a histidine kinase (EC, EnvZ, histidine protein kinase, protein histidine kinase, protein ... protein L-histidine ⇌ {\displaystyle \rightleftharpoons } ADP + protein N-phospho-L-histidine. Thus, the two substrates of this ... the widespread existence of protein histidine phosphorylation distinct from that of two-component histidine kinases has been ... The histidine phosphorylation site is located at His-260. The N, G1, F and G2 boxes are contained in the C-terminal catalytic ...
In enzymology, a histidine transaminase (EC is an enzyme that catalyzes the chemical reaction L-histidine + 2- ... Other names in common use include histidine aminotransferase, and histidine-2-oxoglutarate aminotransferase. This enzyme ... Wickremasinghe R, Hedegaard J, Roche J (1967). "Degradation de la L-histidine chez Escherichia coli B: formation de l'acide ... The systematic name of this enzyme class is L-histidine:2-oxoglutarate aminotransferase. ...
HDC decarboxylates histidine through the use of a PLP cofactor initially bound in a Schiff base to lysine 305. Histidine ... In humans, histidine decarboxylase is encoded by the HDC gene. Histidine decarboxylase is a group II pyridoxal-dependent ... "Entrez Gene: histidine decarboxylase". Riley WD, Snell EE (October 1968). "Histidine decarboxylase of Lactobacillus 30a. IV. ... HDC is highly specific for its histidine substrate. Histidine decarboxylase is the primary biological source of histamine. ...
... histidine):pyruvate aminotransferase, histidine:pyruvate aminotransferase, and L-phenylalanine(L-histidine):pyruvate ... In enzymology, a phenylalanine(histidine) transaminase (EC is an enzyme that catalyzes the chemical reaction L- ... Minatogawa Y, Noguchi T, Kido R (January 1977). "Species distribution and properties of hepatic phenylalanine (histidine): ... Other names in common use include phenylalanine (histidine) aminotransferase, phenylalanine( ...
... may refer to: Histidine kinase, an enzyme Protein-histidine tele-kinase, an enzyme Protein-histidine ... pros-kinase, an enzyme This disambiguation page lists articles associated with the title Protein histidine kinase. If an ...
In enzymology, a histidine-tRNA ligase (EC is an enzyme that catalyzes the chemical reaction ATP + L-histidine + ... This enzyme participates in histidine metabolism and aminoacyl-trna biosynthesis. Histidine-tRNA ligase belongs to the family ... The systematic name of this enzyme class is L-histidine:tRNAHis ligase (AMP-forming). Other names in common use include ... L-histidine, and tRNA(His), whereas its 3 products are AMP, diphosphate, and L-histidyl-tRNA(His). ...
N-acetyl-L-histidine Thus, the two substrates of this enzyme are acetyl-CoA and L-histidine, whereas its two products are CoA ... In enzymology, a histidine N-acetyltransferase (EC is an enzyme that catalyzes the chemical reaction acetyl-CoA + L- ... The systematic name of this enzyme class is acetyl-CoA:L-histidine N-acetyltransferase. Other names in common use include ... Baslow MH (December 1966). "N -acetyl-L-histidine synthetase activity from the brain of the killifish". Brain Research. 3 (2): ...
... together with intensive buffering of the extracellular space by means of histidine/histidine hydrochloride, so as to prolong ... Histidine-tryptophan-ketoglutarate, or Custodiol HTK solution, is a high-flow, low-potassium preservation solution used for ... Finally, histidine is thought to aid buffering, mannitol and tryptophan to improve membrane stability, and ketoglutarate to ... 4. Pokorny H., et al.: Histidine-tryptophan-ketoglutarate solution for organ preservation in human liver transplantation - a ...
a EINECS number 200-745-3 (D-histidine) ^a EINECS number 206-513-8 (L-histidine) ^a CID 71083 from PubChem (D-histidine) ^a CID ... 6274 from PubChem (L-histidine) (Articles with short description, Short description matches Wikidata, PubChem ID (CID) not in ...
It converts histidine into ammonia and urocanic acid. Its systematic name is L-histidine ammonia-lyase (urocanate-forming). ... Histidine ammonia-lyase is a cytosolic enzyme catalyzing the first reaction in histidine catabolism, the nonoxidative ... Histidine ammonia-lyase (EC, histidase, histidinase) is an enzyme that in humans is encoded by the HAL gene. ... "Entrez Gene: histidine ammonia-lyase". Suchi M, Sano H, Mizuno H, Wada Y (September 1995). "Molecular cloning and structural ...
... (HME) is an irreversible histidine decarboxylase inhibitor. It is the methyl ester of histidine. ... Histidine decarboxylase Alpha-Fluoromethylhistidine Lane, Roger S; Manning, James M; Snell, Esmond E (2002). "Histidine ... Alston, Theodore A; Abeles, Robert H (2002). "Reaction of Lactobacillus histidine decarboxylase with L-histidine methyl ester ... Histidine decarboxylase inhibitors, Amino acid derivatives, Imidazoles, Methyl esters, Carboxylate esters, All stub articles, ...
... s and histidine phosphotransferases (both often abbreviated HPt) are protein domains involved ... In orthodox two-component signaling, a histidine kinase protein autophosphorylates on a histidine residue in response to an ... with similarity to the structure of histidine kinases. Monomeric HPt domains possess only one phosphorylatable histidine ... In some cases, a phosphorelay system is constructed from four separate proteins rather than a hybrid histidine kinase with an ...
The Histidine operon leader is an RNA element found in the bacterial histidine operon. At least 6 amino acid operons are known ... Page for Histidine operon leader at Rfam v t e (Cis-regulatory RNA elements, All stub articles, Molecular and cellular biology ...
"Entrez Gene: HRG histidine-rich glycoprotein". Wakabayashi S (2013). New insights into the functions of histidine-rich ... The high concentration of both histidine and proline residues has resulted in HRG also being termed 'histidine-proline-rich ... Histidine-rich glycoprotein (HRG) is a glycoprotein that in humans is encoded by the HRG gene. The HRG protein is produced in ... This histidine-rich glycoprotein contains two cystatin-like domains and is located in plasma and platelets. It is known that ...
... histidine kinase, histidine protein kinase, protein histidine kinase, protein kinase (histidine), and HK3. Fujitaki JM, Fung G ... protein-histidine kinases). The systematic name of this enzyme class is ATP:protein-L-histidine Ntau-phosphotransferase. Other ... protein L-histidine ⇌ {\displaystyle \rightleftharpoons } ADP + protein Nτ-phospho-L-histidine Thus, the two substrates of this ... In enzymology, a protein-histidine tele-kinase (EC is an enzyme that catalyzes the chemical reaction ATP + ...
... (FruHis) is a ketosamine combining the d-isomer of fructose and the l-isomer of histidine into a ... Valeri V. Mossine and Thomas P. Mawhinney (2007). "Nα-(1-Deoxy-D-fructos-1-yl)-L-histidine ("D-Fructose-L-histidine"): a Potent ...
Other names in common use include protein methylase IV, protein (histidine) methyltransferase, actin-specific histidine ... protein L-histidine ⇌ {\displaystyle \rightleftharpoons } S-adenosyl-L-homocysteine + protein Ntau-methyl-L-histidine Thus, the ... In enzymology, a protein-histidine N-methyltransferase (EC is an enzyme that catalyzes the chemical reaction S- ... The systematic name of this enzyme class is S-adenosyl-L-methionine:protein-L-histidine N-tele-methyltransferase. ...
... histidine kinase, histidine protein kinase, protein histidine kinase, protein kinase (histidine), and HK2. Fujitaki JM, Fung G ... protein-histidine kinases). The systematic name of this enzyme class is ATP:protein-L-histidine Npi-phosphotransferase. Other ... protein L-histidine ⇌ {\displaystyle \rightleftharpoons } ADP + protein Nπ-phospho-L-histidine Thus, the two substrates of this ... In enzymology, a protein-histidine pros-kinase (EC is an enzyme that catalyzes the chemical reaction ATP + ...
Like nucleotides, biosynthesis of histidine is initiated by the conversion of R5P to PRPP. The step of histidine biosynthesis ... Histidine biosynthesis is carefully regulated by feedback inhibition/ R5P can be converted to adenosine diphosphate ribose, ... cite book}}: ,journal= ignored (help) Ingle RA (January 2011). "Histidine biosynthesis". The Arabidopsis Book. 9: e0141. doi: ... and histidine. Nucleotides serve as the building blocks for nucleic acids, DNA and RNA. They are composed of a nitrogenous base ...
Examples include cystine from hydrolysis of hair, tryptophane from casein, histidine from red blood cells, and arginine from ... Foster, G. L.; Shemin, D. (1938). "L-Histidine Monohydrochloride". Organic Syntheses. 18: 43. doi:10.15227/orgsyn.018.0043. ...
3-Methyl-L-histidine. 23 December 2017. Retrieved 25 December 2017. {{cite encyclopedia}}: ,work= ignored (help) Chinkes DL ( ... 3-Methylhistidine is a metabolic product that is produced in the body via the enzymatic methylation of histidine during peptide ...
This enzyme participates in histidine metabolism as it is involved in the 6th step of histidine biosynthesis as part of a nine ... AMES BN (1957). "The biosynthesis of histidine; D-erythro-imidazoleglycerol phosphate dehydrase". J. Biol. Chem. 228 (1): 131- ... "Structure and function of the Salmonella typhimurium and Escherichia coli K-12 histidine operons". J. Mol. Biol. 203 (3): 585- ...
There are also protein kinases that phosphorylate other amino acids, including histidine kinases that phosphorylate histidine ... Histidine kinases are structurally distinct from most other protein kinases and are found mostly in prokaryotes as part of two- ... Histidine kinases are found widely in prokaryotes, as well as in plants, fungi and eukaryotes. The pyruvate dehydrogenase ... A phosphate group from ATP is first added to a histidine residue within the kinase, and later transferred to an aspartate ...
Ames BN (June 1957). "The biosynthesis of histidine; L-histidinol phosphate phosphatase". The Journal of Biological Chemistry. ... phosphate This enzyme participates in histidine metabolism. This enzyme belongs to the family of hydrolases, to be specific, ...
Carbon atoms from ribose in PRPP form the linear chain and part of the imidazole ring in histidine. The same is true for the ... The histidine biosynthesis pathway involves the reaction between PRPP and ATP, which activates the latter to ring cleavage. ... Stepansky, A.; Leustek, T. (2006). "Histidine biosynthesis in plants". Amino Acids. 30 (2): 127-142. doi:10.1007/s00726-005- ... L-histidine biosynthesis". MetaCyc Metabolic Pathway Database. Retrieved 2022-02-17. ...
It is a secondary disorder of histidine metabolism. Urocanic aciduria is thought to be relatively benign. Although aggressive ... The amino acid histidine, when catalyzed by the enzyme histidase, forms urocanic acid. Disruptions in this pathway, caused by a ... With normal to only slightly elevated levels of histidine present in the liver during urocanic aciduria, the only true ... Disorders of histidine metabolism. ...
Phosphorylation usually occurs on serine, threonine, tyrosine and histidine residues in eukaryotic proteins. Histidine ... Histidine and aspartate phosphorylation occurs in prokaryotes as part of two-component signaling and in some cases in ... Once histidine is phosphorylated the regulatory domain of the response regulator catalyzes the transfer of the phosphate to ... and In prokaryotes, archea, and some lower eukaryotes histidine's nitrogen act as a nucleophile and binds to a phosphate group ...
Lysine, Histidine, Arginine, and Valine". Proceedings of the Society for Experimental Biology and Medicine. 61 (2): 158-161. ... Rosenthaler, J.; Guirard, B. M.; Chang, G. W.; Snell, E. E. (1965-07-01). "Purification and properties of histidine ... Guirard, B M; Tanase, S; Snell, E E (1984-01-01). "Pyridoxal-P dependent bacterial histidine decarboxylase". Progress in ... Rosenthaler, J.; Guirard, B. M.; Chang, G. W.; Snell, E. E. (1965-07-01). "Purification and properties of histidine ...
Rose's later work showed that eight amino acids are essential for adult human beings, with histidine also being essential for ... Kopple JD, Swendseid ME (May 1975). "Evidence that histidine is an essential amino acid in normal and chronically uremic man". ... Of the twenty amino acids common to all life forms (not counting selenocysteine), humans cannot synthesize nine: histidine, ... The role of threonine and histidine". The Journal of Biological Chemistry. 188 (1): 49-58. doi:10.1016/S0021-9258(18)56144-5. ...
Humans and other animals must ingest histidine or histidine-containing proteins. The biosynthesis of histidine has been widely ... In a histidine proton shuttle, histidine is used to quickly shuttle protons. It can do this by abstracting a proton with its ... For histidine, for adults 19 years and older, 14 mg/kg body weight/day. Supplemental histidine is being investigated for use in ... Histidine forms complexes with many metal ions. The imidazole sidechain of the histidine residue commonly serves as a ligand in ...
L-Histidine , EC Number: 200-745-3; Synonym: (S)-2-Amino-3-(4-imidazolyl)propionic acid, NSC 137773; Linear Formula: C6H9N3O2 ... L-Histidine is an essential amino acid.. It binds to metal ions and may aid in the transport of copper.. Histidine is widely ... L-histidine has been used for the selection of transformed cells.. It has also been used to study its effects on the formation ...
J:71004 Hulett MD, et al., Murine histidine-rich glycoprotein: cloning, characterization and cellular origin. Immunol Cell Biol ...
To prevent the binding of host cell proteins with exposed histidines, it is essential to include imidazole at a low ... The chromatography medium provides very high binding capacity for histidine-tagged proteins and shows negligible leakage of Ni ... Figure 1.Ni Sepharose High Performance precharged with Ni2+ for high-performance purification of histidine-tagged proteins. ... concentration in the sample and binding buffer (Optimizing purification of histidine-tagged proteins). ...
Crystal Structure of Histidine-containing Phosphotransfer Protein MtHPt1 from Medicago truncatula ... Histidine-containing Phosphotransfer Protein type 1, MtHPt1. A. 153. Medicago truncatula. Mutation(s): 0 Gene Names: MtHPt, ... HPts function in histidine-aspartate phosphorelays in which they mediate the signal from sensory kinases (usually membrane ... Histidine-containing phosphotransfer proteins (HPts) take part in hormone signal transduction in higher plants. The overall ...
GE Healthcare has announced the availability of its single-use spin column designed for purification of histidine-tagged ... GEs launch histidine-tagged protein spin columns. By Wai Lang Chu 08-Dec-2005. - Last updated on 19-Jul-2008 at 14:21. GMT ... Ni Sepharose provides a high binding capacity-up to 750 µg of pure histidine-tagged protein per column-and compatibility with a ... column designed for purification of histidine-tagged proteins using a standard microcentrifuge. It saves researchers time as it ...
AMR Network/Working Group on Histidine Kinase Inhibitors as Novel Anti-infectives. Status: Completed Start project:. Jan 1, ... International Working Group on Histidine Kinase Inhibitors as Novel Anti-infectives. New antibacterials are urgently needed ... We have previously identified a panel of inhibitors targeting bacterial histidine kinases in bacteria that inhibit targets ... and combining expertise to devise the most efficient strategy to further develop new anti-infective drugs targeted to histidine ...
histidine. J. Huang and J. A. Cowan, Chem. Commun., 2009, 3071 DOI: 10.1039/B902676B ...
Antibodies for proteins involved in histidine catabolic process to glutamate and formamide pathways, according to their Panther ...
Major Threat to Malaria Control Programs by Plasmodium falciparum Lacking Histidine-Rich Protein 2, Eritrea Araia Berhane, ... Major Threat to Malaria Control Programs by Plasmodium falciparum Lacking Histidine-Rich Protein 2, Eritrea. ... for analysis of a major threat to malaria control programs by Plasmodium falciparum lacking histidine-rich protein 2. Inset ...
Copper binding and reactivity at the histidine brace motif: insights from mutational analysis of the Pseudomonas fluorescens ...
Structure Determination from Backbone Amide Pseudocontact Shifts Generated by Double-histidine Cobalt Tags. ...
Sensor histidine kinase TM0853 [140494] (1 species). *. Species Thermotoga maritima [TaxId:2336] [140495] (1 PDB entry). ... Timeline for Family a.30.2.1: Homodimeric domain of signal transducing histidine kinase: *Family a.30.2.1: Homodimeric domain ... Lineage for Family a.30.2.1: Homodimeric domain of signal transducing histidine kinase. *Root: SCOPe 2.08 *. Class a: All alpha ... More info for Family a.30.2.1: Homodimeric domain of signal transducing histidine kinase. ...
Poly-histidine peptides such as H6 (HHHHHH) are used in protein biotechnologies as purification tags, pro- tein-assembling ... In this study, we have explored several humanized histidine-rich peptides in tumor-targeted modular proteins, which can ... CitationLopez-Laguna, H. [et al.]. Endosomal escape of protein nanoparticles engineered through humanized histidine-rich ... self-assembling and endosomal escape perform in proteins containing the variant histidine-rich tags. Among the tested ...
Histidine dipeptides are key regulators of excitation-contraction coupling in cardiac muscle: Evidence from a novel CARNS1 ... Histidine-containing dipeptides (HCDs) are abundantly expressed in striated muscles. Although important properties have been ... Histidine dipeptides are key regulators of excitation-contraction coupling in cardiac muscle: Evidence from a novel CARNS1 ... Histidine-containing dipeptides (HCDs) are abundantly expressed in striated muscles. Although important properties have been ...
CIL) offers product CLM-2264-0.25 L-Histidine·HCl·H₂O (¹³C₆, 97-99%) ,5% D ...
HISTIDINE (UNII: 4QD397987E) (HISTIDINE - UNII:4QD397987E) HISTIDINE. 200 [kp_C] in 1 mL. ... Label: NEURO 3 (oxitriptan, acetylcholinesterase human, choline chloride, dopamine, glutamic acid, glycine, histidine, levodopa ... NEURO 3 (oxitriptan, acetylcholinesterase human, choline chloride, dopamine, glutamic acid, glycine, histidine, levodopa, ... NEURO 3 (oxitriptan, acetylcholinesterase human, choline chloride, dopamine, glutamic acid, glycine, histidine, levodopa, ...
Histidine kinase 2 (Hik2) is a sensor histidine kinase found in all known cyanobacteria and as chloroplast sensor kinase in ... Oligomeric states in sodium ion-dependent regulation of cyanobacterial histidine kinase-2. View ORCID ProfileIskander M. ... Histidine kinase 2 is a sensor of sodium ion concentration and redox potential, regulating transcription of genes for light- ... The sensor component is a protein that becomes covalently modified by a phosphate group on a histidine side chain. The response ...
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... activity against Plasmodium falciparum isolates assessed as parasite growth inhibition after 72 hrs by ELISA based histidine- ...
Interaction of a Histidine-Rich Antimicrobial Saliva Peptide with Model Cell Membranes : The Role of Histidines. *Mark ... Interaction of a Histidine-Rich Antimicrobial Saliva Peptide with Model Cell Membranes : The Role of Histidines}}, url = {{http ... where all variants except the one with zero histidines were found below the bilayer. A decrease in the number of histidine from ... where all variants except the one with zero histidines were found below the bilayer. A decrease in the number of histidine from ...
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A comparative study of Plasmodium falciparum histidine-rich protein 2 (PfHRP2) blood levels and peripheral blood parasitemia as ... 2021). A comparative study of Plasmodium falciparum histidine-rich protein 2 (PfHRP2) blood levels and peripheral blood ... A_comparative_study_of_Plasmodium_falciparum_histidine_rich_protein_2_PfHRP2_.pdf ...
In the present study, essential histidine and cysteine residues of MATE1 family were elucidated. When 7 histidine and 12 ... Identification of Essential Histidine and Cysteine Residues of the H+/Organic Cation Antiporter Multidrug and Toxin Extrusion ( ... Identification of Essential Histidine and Cysteine Residues of the H+/Organic Cation Antiporter Multidrug and Toxin Extrusion ( ... Identification of Essential Histidine and Cysteine Residues of the H+/Organic Cation Antiporter Multidrug and Toxin Extrusion ( ...
The pH-dependent Client Release from the Collagen-specific Chaperone HSP47 Is Triggered by a Tandem Histidine Pair. J. Biol. ... We present here an extensive theoretical and experimental study of the 14 histidine residues present in canine HSP47, where we ... The pH-dependent Client Release from the Collagen-specific Chaperone HSP47 Is Triggered by a Tandem Histidine Pair ... Histidine residues have been suggested as triggers due to their approximate textbook pK(a) value of 6.1 for their side chains. ...
Identification of specific histidines as pH sensors in flavivirus membrane fusion Richard Fritz, Richard Fritz ... Five histidine residues, located in DI, II, and III as well as in the stem region (Fig. 1, B and C), are conserved among all ... To replace the histidines, we used alanine as a first choice, but, if an alanine mutation did not yield RSPs conforming to all ... A conserved histidine in the ij loop of the Semliki Forest virus E1 protein plays an important role in membrane fusion. J. ...
"Histidine" is a descriptor in the National Library of Medicines controlled vocabulary thesaurus, MeSH (Medical Subject ... This graph shows the total number of publications written about "Histidine" by people in this website by year, and whether " ... Below are the most recent publications written about "Histidine" by people in Profiles. ...
Essential amino acids are in some of the powders to improve our athletic performance. Amino acids are the foundational proteins from which we are built.. ...

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