Compounds based on 5,6,7,8-tetrahydrofolate.
A member of the vitamin B family that stimulates the hematopoietic system. It is present in the liver and kidney and is found in mushrooms, spinach, yeast, green leaves, and grasses (POACEAE). Folic acid is used in the treatment and prevention of folate deficiencies and megaloblastic anemia.
An enzyme that catalyzes the formation of methionine by transfer of a methyl group from 5-methyltetrahydrofolate to homocysteine. It requires a cobamide coenzyme. The enzyme can act on mono- or triglutamate derivatives. EC
A subclass of enzymes of the transferase class that catalyze the transfer of a methyl group from one compound to another. (Dorland, 28th ed) EC 2.1.1.
Cell surface receptors that bind to and transport FOLIC ACID, 5-methyltetrahydrofolate, and a variety of folic acid derivatives. The receptors are essential for normal NEURAL TUBE development and transport folic acid via receptor-mediated endocytosis.
An FAD-dependent oxidoreductase found primarily in BACTERIA. It is specific for the reduction of 5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate. This enzyme was formerly listed as EC and
An enzyme that catalyzes the transfer of a methyl group from S-ADENOSYLMETHIONINE to the 5-position of CYTOSINE residues in DNA.
A cobalt-containing coordination compound produced by intestinal micro-organisms and found also in soil and water. Higher plants do not concentrate vitamin B 12 from the soil and so are a poor source of the substance as compared with animal tissues. INTRINSIC FACTOR is important for the assimilation of vitamin B 12.
Tetrahydrofolates which are substituted by a formyl group at either the nitrogen atom in the 5 position or the nitrogen atom in the 10 position. N(5)-Formyltetrahydrofolate is leukovorin (citrovorum factor) while N(10)-formyltetrahydrofolate is an active coenzyme which functions as a carrier of the formyl group in a number of enzymatic reactions.
Physiologic methyl radical donor involved in enzymatic transmethylation reactions and present in all living organisms. It possesses anti-inflammatory activity and has been used in treatment of chronic liver disease. (From Merck, 11th ed)
A flavoprotein amine oxidoreductase that catalyzes the reversible conversion of 5-methyltetrahydrofolate to 5,10-methylenetetrahydrofolate. This enzyme was formerly classified as EC
Derivatives of folic acid (pteroylglutamic acid). In gamma-glutamyl linkage they are found in many tissues. They are converted to folic acid by the action of pteroylpolyglutamate hydrolase or synthesized from folic acid by the action of folate polyglutamate synthetase. Synthetic pteroylpolyglutamic acids, which are in alpha-glutamyl linkage, are active in bacterial growth assays.
Results of conception and ensuing pregnancy, including LIVE BIRTH; STILLBIRTH; SPONTANEOUS ABORTION; INDUCED ABORTION. The outcome may follow natural or artificial insemination or any of the various ASSISTED REPRODUCTIVE TECHNIQUES, such as EMBRYO TRANSFER or FERTILIZATION IN VITRO.
Condition in which the plasma levels of homocysteine and related metabolites are elevated (>13.9 µmol/l). Hyperhomocysteinemia can be familial or acquired. Development of the acquired hyperhomocysteinemia is mostly associated with vitamins B and/or folate deficiency (e.g., PERNICIOUS ANEMIA, vitamin malabsorption). Familial hyperhomocysteinemia often results in a more severe elevation of total homocysteine and excretion into the urine, resulting in HOMOCYSTINURIA. Hyperhomocysteinemia is a risk factor for cardiovascular and neurodegenerative diseases, osteoporotic fractures and complications during pregnancy.
An enzyme that catalyzes the METHYLATION of GLYCINE using S-ADENOSYLMETHIONINE to form SARCOSINE with the concomitant production of S-ADENOSYLHOMOCYSTEINE.
5'-S-(3-Amino-3-carboxypropyl)-5'-thioadenosine. Formed from S-adenosylmethionine after transmethylation reactions.
A group of cytosine ribonucleotides in which the phosphate residues of each cytosine ribonucleotide act as bridges in forming diester linkages between the ribose moieties.
A thiol-containing amino acid formed by a demethylation of METHIONINE.
Enzymes catalyzing the dehydrogenation of secondary amines, introducing a C=N double bond as the primary reaction. In some cases this is later hydrolyzed.
Enzymes that catalyze the methylation of amino acids after their incorporation into a polypeptide chain. S-Adenosyl-L-methionine acts as the methylating agent. EC 2.1.1.
A ubiquitously expressed folic acid transporter that functions via an antiporter mechanism which is coupled to the transport of organic phosphates.
An enzyme that transfers methyl groups from O(6)-methylguanine, and other methylated moieties of DNA, to a cysteine residue in itself, thus repairing alkylated DNA in a single-step reaction. EC
A ZINC metalloenzyme that catalyzes the transfer of a methyl group from BETAINE to HOMOCYSTEINE to produce dimethylglycine and METHIONINE, respectively. This enzyme is a member of a family of ZINC-dependent METHYLTRANSFERASES that use THIOLS or selenols as methyl acceptors.
Anemia characterized by larger than normal erythrocytes, increased mean corpuscular volume (MCV) and increased mean corpuscular hemoglobin (MCH).
A nutritional condition produced by a deficiency of VITAMIN B 12 in the diet, characterized by megaloblastic anemia. Since vitamin B 12 is not present in plants, humans have obtained their supply from animal products, from multivitamin supplements in the form of pills, and as additives to food preparations. A wide variety of neuropsychiatric abnormalities is also seen in vitamin B 12 deficiency and appears to be due to an undefined defect involving myelin synthesis. (From Cecil Textbook of Medicine, 19th ed, p848)
An enzyme that catalyzes the methylation of the epsilon-amino group of lysine residues in proteins to yield epsilon mono-, di-, and trimethyllysine. EC
Enzymes that catalyze the S-adenosyl-L-methionine-dependent methylation of ribonucleotide bases within a transfer RNA molecule. EC 2.1.1.
A group of water-soluble vitamins, some of which are COENZYMES.
A plant genus of the family SALICACEAE. Balm of Gilead is a common name used for P. candicans, or P. gileadensis, or P. jackii, and sometimes also used for ABIES BALSAMEA or for COMMIPHORA.
Enzymes that catalyze the methylation of arginine residues of proteins to yield N-mono- and N,N-dimethylarginine. This enzyme is found in many organs, primarily brain and spleen.
A nutritional condition produced by a deficiency of FOLIC ACID in the diet. Many plant and animal tissues contain folic acid, abundant in green leafy vegetables, yeast, liver, and mushrooms but destroyed by long-term cooking. Alcohol interferes with its intermediate metabolism and absorption. Folic acid deficiency may develop in long-term anticonvulsant therapy or with use of oral contraceptives. This deficiency causes anemia, macrocytic anemia, and megaloblastic anemia. It is indistinguishable from vitamin B 12 deficiency in peripheral blood and bone marrow findings, but the neurologic lesions seen in B 12 deficiency do not occur. (Merck Manual, 16th ed)
Injectable form of VITAMIN B 12 that has been used therapeutically to treat VITAMIN B 12 DEFICIENCY.
Cyclic TETRAPYRROLES based on the corrin skeleton.
Methylases that are specific for CYTOSINE residues found on DNA.
A PROTEIN O-METHYLTRANSFERASE that recognizes and catalyzes the methyl esterification of ISOASPARTIC ACID and D-ASPARTIC ACID residues in peptides and proteins. It initiates the repair of proteins damaged by the spontaneous decomposition of normal L-aspartic acid and L-asparagine residues.
Enzymes that are part of the restriction-modification systems. They are responsible for producing a species-characteristic methylation pattern, on either adenine or cytosine residues, in a specific short base sequence in the host cell's own DNA. This methylated sequence will occur many times in the host-cell DNA and remain intact for the lifetime of the cell. Any DNA from another species which gains entry into a living cell and lacks the characteristic methylation pattern will be recognized by the restriction endonucleases of similar specificity and destroyed by cleavage. Most have been studied in bacterial systems, but a few have been found in eukaryotic organisms.
An enzyme responsible for producing a species-characteristic methylation pattern on adenine residues in a specific short base sequence in the host cell DNA. The enzyme catalyzes the methylation of DNA adenine in the presence of S-adenosyl-L-methionine to form DNA containing 6-methylaminopurine and S-adenosyl-L-homocysteine. EC
A naturally occurring compound that has been of interest for its role in osmoregulation. As a drug, betaine hydrochloride has been used as a source of hydrochloric acid in the treatment of hypochlorhydria. Betaine has also been used in the treatment of liver disorders, for hyperkalemia, for homocystinuria, and for gastrointestinal disturbances. (From Martindale, The Extra Pharmacopoeia, 30th ed, p1341)
Inhibitors of the enzyme, dihydrofolate reductase (TETRAHYDROFOLATE DEHYDROGENASE), which converts dihydrofolate (FH2) to tetrahydrofolate (FH4). They are frequently used in cancer chemotherapy. (From AMA, Drug Evaluations Annual, 1994, p2033)
Addition of methyl groups to DNA. DNA methyltransferases (DNA methylases) perform this reaction using S-ADENOSYLMETHIONINE as the methyl group donor.
A multifunctional pyridoxal phosphate enzyme. In the second stage of cysteine biosynthesis it catalyzes the reaction of homocysteine with serine to form cystathionine with the elimination of water. Deficiency of this enzyme leads to HYPERHOMOCYSTEINEMIA and HOMOCYSTINURIA. EC
Compounds based on 2-amino-4-hydroxypteridine.
A peptide that is a homopolymer of glutamic acid.
Products in capsule, tablet or liquid form that provide dietary ingredients, and that are intended to be taken by mouth to increase the intake of nutrients. Dietary supplements can include macronutrients, such as proteins, carbohydrates, and fats; and/or MICRONUTRIENTS, such as VITAMINS; MINERALS; and PHYTOCHEMICALS.
A subtype of GPI-anchored folate receptors that is expressed in tissues of epithelial origin. This protein is also identified as an ovarian-tumor-specific antigen.
A symporter protein that couples the transport of FOLIC ACID with HYDROGEN IONS. The transporter functions most effectively under acidic conditions.
Nitrogen oxide (N2O). A colorless, odorless gas that is used as an anesthetic and analgesic. High concentrations cause a narcotic effect and may replace oxygen, causing death by asphyxia. It is also used as a food aerosol in the preparation of whipping cream.
Transport proteins that carry specific substances in the blood or across cell membranes.
Compounds based on pyrazino[2,3-d]pyrimidine which is a pyrimidine fused to a pyrazine, containing four NITROGEN atoms.
Catalyzes the hydrolysis of pteroylpolyglutamic acids in gamma linkage to pterolylmonoglutamic acid and free glutamic acid. EC
Cell surface proteins that bind signalling molecules external to the cell with high affinity and convert this extracellular event into one or more intracellular signals that alter the behavior of the target cell (From Alberts, Molecular Biology of the Cell, 2nd ed, pp693-5). Cell surface receptors, unlike enzymes, do not chemically alter their ligands.
A genus of motile or nonmotile gram-positive bacteria of the family Clostridiaceae. Many species have been identified with some being pathogenic. They occur in water, soil, and in the intestinal tract of humans and lower animals.
A CALCIUM-dependent endopeptidase that has specificity for cleavage at ARGININE that is near paired basic residues. It cleaves a variety of prohormones including PRO-OPIOMELANOCORTIN; PRORENIN; proenkephalins; prodynorphin; prosomatostatin; and PROINSULIN.
VITAMIN B 6 refers to several PICOLINES (especially PYRIDOXINE; PYRIDOXAL; & PYRIDOXAMINE) that are efficiently converted by the body to PYRIDOXAL PHOSPHATE which is a coenzyme for synthesis of amino acids, neurotransmitters (serotonin, norepinephrine), sphingolipids, and aminolevulinic acid. During transamination of amino acids, pyridoxal phosphate is transiently converted into PYRIDOXAMINE phosphate. Although pyridoxine and Vitamin B 6 are still frequently used as synonyms, especially by medical researchers, this practice is erroneous and sometimes misleading (EE Snell; Ann NY Acad Sci, vol 585 pg 1, 1990). Most of vitamin B6 is eventually degraded to PYRIDOXIC ACID and excreted in the urine.
The extent to which the active ingredient of a drug dosage form becomes available at the site of drug action or in a biological medium believed to reflect accessibility to a site of action.
The movement of materials (including biochemical substances and drugs) through a biological system at the cellular level. The transport can be across cell membranes and epithelial layers. It also can occur within intracellular compartments and extracellular compartments.
Liquid chromatographic techniques which feature high inlet pressures, high sensitivity, and high speed.
Congenital malformations of the central nervous system and adjacent structures related to defective neural tube closure during the first trimester of pregnancy generally occurring between days 18-29 of gestation. Ectodermal and mesodermal malformations (mainly involving the skull and vertebrae) may occur as a result of defects of neural tube closure. (From Joynt, Clinical Neurology, 1992, Ch55, pp31-41)
A megaloblastic anemia occurring in children but more commonly in later life, characterized by histamine-fast achlorhydria, in which the laboratory and clinical manifestations are based on malabsorption of vitamin B 12 due to a failure of the gastric mucosa to secrete adequate and potent intrinsic factor. (Dorland, 27th ed)
A natural product that has been considered as a growth factor for some insects.
A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances.
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.
Red blood cells. Mature erythrocytes are non-nucleated, biconcave disks containing HEMOGLOBIN whose function is to transport OXYGEN.
An enzyme that catalyses three sequential METHYLATION reactions for conversion of phosphatidylethanolamine to PHOSPHATIDYLCHOLINE.
Small chromosomal proteins (approx 12-20 kD) possessing an open, unfolded structure and attached to the DNA in cell nuclei by ionic linkages. Classification into the various types (designated histone I, histone II, etc.) is based on the relative amounts of arginine and lysine in each.
The genetic constitution of the individual, comprising the ALLELES present at each GENETIC LOCUS.
An enzyme that catalyzes the transfer of methyl groups from S-adenosylmethionine to free carboxyl groups of a protein molecule forming methyl esters. EC 2.1.1.-.
This enzyme catalyzes the last step of CREATINE biosynthesis by catalyzing the METHYLATION of guanidinoacetate to CREATINE.
An enzyme that catalyzes the METHYLATION of phosphatidyl-N-methylethanolamine to produce phosphatidyl-N-dimethylethanolamine. This enzyme can also methylate phosphatidyl-N-dimethylethanolamine to produce phosphatidyl-N-trimethylethanolamine (PHOSPHATIDYLCHOLINE).
An enzyme that catalyzes the demethylation of L-homocysteine to L-METHIONINE.
Autosomal recessive inborn error of methionine metabolism usually caused by a deficiency of CYSTATHIONINE BETA-SYNTHASE and associated with elevations of homocysteine in plasma and urine. Clinical features include a tall slender habitus, SCOLIOSIS, arachnodactyly, MUSCLE WEAKNESS, genu varus, thin blond hair, malar flush, lens dislocations, an increased incidence of MENTAL RETARDATION, and a tendency to develop fibrosis of arteries, frequently complicated by CEREBROVASCULAR ACCIDENTS and MYOCARDIAL INFARCTION. (From Adams et al., Principles of Neurology, 6th ed, p979)
Acetyl CoA participates in the biosynthesis of fatty acids and sterols, in the oxidation of fatty acids and in the metabolism of many amino acids. It also acts as a biological acetylating agent.
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.
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 pyrimidine analogue that inhibits DNA methyltransferase, impairing DNA methylation. It is also an antimetabolite of cytidine, incorporated primarily into RNA. Azacytidine has been used as an antineoplastic agent.
The regular and simultaneous occurrence in a single interbreeding population of two or more discontinuous genotypes. The concept includes differences in genotypes ranging in size from a single nucleotide site (POLYMORPHISM, SINGLE NUCLEOTIDE) to large nucleotide sequences visible at a chromosomal level.
Derivatives of GLUTAMIC ACID. Included under this heading are a broad variety of acid forms, salts, esters, and amides that contain the 2-aminopentanedioic acid structure.
An individual in which both alleles at a given locus are identical.
A characteristic feature of enzyme activity in relation to the kind of substrate on which the enzyme or catalytic molecule reacts.
A tumor-like inflammatory lesion of the lung that is composed of PLASMA CELLS and fibrous tissue. It is also known as an inflammatory pseudotumor, often with calcification and measuring between 2 and 5 cm in diameter.
A multisubunit polycomb protein complex that catalyzes the METHYLATION of chromosomal HISTONE H3. It works in conjunction with POLYCOMB REPRESSIVE COMPLEX 1 to effect EPIGENETIC REPRESSION.
An enzyme of the oxidoreductase class that catalyzes the reaction 7,8-dihyrofolate and NADPH to yield 5,6,7,8-tetrahydrofolate and NADPH+, producing reduced folate for amino acid metabolism, purine ring synthesis, and the formation of deoxythymidine monophosphate. Methotrexate and other folic acid antagonists used as chemotherapeutic drugs act by inhibiting this enzyme. (Dorland, 27th ed) EC
The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.
Membrane proteins whose primary function is to facilitate the transport of molecules across a biological membrane. Included in this broad category are proteins involved in active transport (BIOLOGICAL TRANSPORT, ACTIVE), facilitated transport and ION CHANNELS.
Composition of images of EARTH or other planets from data collected during SPACE FLIGHT by remote sensing instruments onboard SPACECRAFT. The satellite sensor systems measure and record absorbed, emitted, or reflected energy across the spectra, as well as global position and time.
A malonic acid derivative which is a vital intermediate in the metabolism of fat and protein. Abnormalities in methylmalonic acid metabolism lead to methylmalonic aciduria. This metabolic disease is attributed to a block in the enzymatic conversion of methylmalonyl CoA to succinyl CoA.
Established cell cultures that have the potential to propagate indefinitely.
Stable carbon atoms that have the same atomic number as the element carbon, but differ in atomic weight. C-13 is a stable carbon isotope.
An essential amino acid. It is often added to animal feed.
A genetic process by which the adult organism is realized via mechanisms that lead to the restriction in the possible fates of cells, eventually leading to their differentiated state. Mechanisms involved cause heritable changes to cells without changes to DNA sequence such as DNA METHYLATION; HISTONE modification; DNA REPLICATION TIMING; NUCLEOSOME positioning; and heterochromatization which result in selective gene expression or repression.
A pyrimidine base that is a fundamental unit of nucleic acids.
Interruption or suppression of the expression of a gene at transcriptional or translational levels.
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).
Elements of limited time intervals, contributing to particular results or situations.
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)
Chromatography on non-ionic gels without regard to the mechanism of solute discrimination.
Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.
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.
A thiol-containing non-essential amino acid that is oxidized to form CYSTINE.
The phenomenon whereby compounds whose molecules have the same number and kind of atoms and the same atomic arrangement, but differ in their spatial relationships. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 5th ed)
A method of studying a drug or procedure in which both the subjects and investigators are kept unaware of who is actually getting which specific treatment.
A mass spectrometry technique using two (MS/MS) or more mass analyzers. With two in tandem, the precursor ions are mass-selected by a first mass analyzer, and focused into a collision region where they are then fragmented into product ions which are then characterized by a second mass analyzer. A variety of techniques are used to separate the compounds, ionize them, and introduce them to the first mass analyzer. For example, for in GC-MS/MS, GAS CHROMATOGRAPHY-MASS SPECTROMETRY is involved in separating relatively small compounds by GAS CHROMATOGRAPHY prior to injecting them into an ionization chamber for the mass selection.
DNA sequences which are recognized (directly or indirectly) and bound by a DNA-dependent RNA polymerase during the initiation of transcription. Highly conserved sequences within the promoter include the Pribnow box in bacteria and the TATA BOX in eukaryotes.
An enzyme which catalyzes the catabolism of S-ADENOSYLHOMOCYSTEINE to ADENOSINE and HOMOCYSTEINE. It may play a role in regulating the concentration of intracellular adenosylhomocysteine.
The 4-methanol form of VITAMIN B 6 which is converted to PYRIDOXAL PHOSPHATE which is a coenzyme for synthesis of amino acids, neurotransmitters (serotonin, norepinephrine), sphingolipids, aminolevulinic acid. Although pyridoxine and Vitamin B 6 are still frequently used as synonyms, especially by medical researchers, this practice is erroneous and sometimes misleading (EE Snell; Ann NY Acad Sci, vol 585 pg 1, 1990).
Body organ that filters blood for the secretion of URINE and that regulates ion concentrations.
Areas of increased density of the dinucleotide sequence cytosine--phosphate diester--guanine. They form stretches of DNA several hundred to several thousand base pairs long. In humans there are about 45,000 CpG islands, mostly found at the 5' ends of genes. They are unmethylated except for those on the inactive X chromosome and some associated with imprinted genes.
Highly reactive compounds produced when oxygen is reduced by a single electron. In biological systems, they may be generated during the normal catalytic function of a number of enzymes and during the oxidation of hemoglobin to METHEMOGLOBIN. In living organisms, SUPEROXIDE DISMUTASE protects the cell from the deleterious effects of superoxides.
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 property of objects that determines the direction of heat flow when they are placed in direct thermal contact. The temperature is the energy of microscopic motions (vibrational and translational) of the particles of atoms.
Nucleic acid structures found on the 5' end of eukaryotic cellular and viral messenger RNA and some heterogeneous nuclear RNAs. These structures, which are positively charged, protect the above specified RNAs at their termini against attack by phosphatases and other nucleases and promote mRNA function at the level of initiation of translation. Analogs of the RNA caps (RNA CAP ANALOGS), which lack the positive charge, inhibit the initiation of protein synthesis.
The degree of similarity between sequences of amino acids. This information is useful for the analyzing genetic relatedness of proteins and species.
A vitamin found in green vegetables. It is used in the treatment of peptic ulcers, colitis, and gastritis and has an effect on secretory, acid-forming, and enzymatic functions of the intestinal tract.
An amino acid intermediate in the metabolism of choline.
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.
An aspect of personal behavior or lifestyle, environmental exposure, or inborn or inherited characteristic, which, on the basis of epidemiologic evidence, is known to be associated with a health-related condition considered important to prevent.
Proteins which maintain the transcriptional quiescence of specific GENES or OPERONS. Classical repressor proteins are DNA-binding proteins that are normally bound to the OPERATOR REGION of an operon, or the ENHANCER SEQUENCES of a gene until a signal occurs that causes their release.
An antineoplastic agent. It has significant activity against melanomas. (from Martindale, The Extra Pharmacopoeia, 31st ed, p564)
A class of drugs that differs from other alkylating agents used clinically in that they are monofunctional and thus unable to cross-link cellular macromolecules. Among their common properties are a requirement for metabolic activation to intermediates with antitumor efficacy and the presence in their chemical structures of N-methyl groups, that after metabolism, can covalently modify cellular DNA. The precise mechanisms by which each of these drugs acts to kill tumor cells are not completely understood. (From AMA, Drug Evaluations Annual, 1994, p2026)
Myeloid-lymphoid leukemia protein is a transcription factor that maintains high levels of HOMEOTIC GENE expression during development. The GENE for myeloid-lymphoid leukemia protein is commonly disrupted in LEUKEMIA and combines with over 40 partner genes to form FUSION ONCOGENE PROTEINS.
The biosynthesis of RNA carried out on a template of DNA. The biosynthesis of DNA from an RNA template is called REVERSE TRANSCRIPTION.
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.
A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine).
The parts of a macromolecule that directly participate in its specific combination with another molecule.
A condition due to deficiency in any member of the VITAMIN B COMPLEX. These B vitamins are water-soluble and must be obtained from the diet because they are easily lost in the urine. Unlike the lipid-soluble vitamins, they cannot be stored in the body fat.
A group of carrier proteins which bind with VITAMIN B12 in the BLOOD and aid in its transport. Transcobalamin I migrates electrophoretically as a beta-globulin, while transcobalamins II and III migrate as alpha-globulins.
Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control of gene action in enzyme synthesis.
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.
Models used experimentally or theoretically to study molecular shape, electronic properties, or interactions; includes analogous molecules, computer-generated graphics, and mechanical structures.
An ASPARTIC ACID residue in polypeptide chains that is linked at the beta-carboxyl group instead of at the normal, alpha-carboxyl group, polypeptide linkage. It is a result of the spontaneous decomposition of aspartic acid or ASPARAGINE residues.
The facilitation of a chemical reaction by material (catalyst) that is not consumed by the reaction.
RNA sequences that serve as templates for protein synthesis. Bacterial mRNAs are generally primary transcripts in that they do not require post-transcriptional processing. Eukaryotic mRNA is synthesized in the nucleus and must be exported to the cytoplasm for translation. Most eukaryotic mRNAs have a sequence of polyadenylic acid at the 3' end, referred to as the poly(A) tail. The function of this tail is not known for certain, but it may play a role in the export of mature mRNA from the nucleus as well as in helping stabilize some mRNA molecules by retarding their degradation in the cytoplasm.
The material of CHROMOSOMES. It is a complex of DNA; HISTONES; and nonhistone proteins (CHROMOSOMAL PROTEINS, NON-HISTONE) found within the nucleus of a cell.
A nutritional condition produced by a deficiency of VITAMIN B 6 in the diet, characterized by dermatitis, glossitis, cheilosis, and stomatitis. Marked deficiency causes irritability, weakness, depression, dizziness, peripheral neuropathy, and seizures. In infants and children typical manifestations are diarrhea, anemia, and seizures. Deficiency can be caused by certain medications, such as isoniazid.
The time frame after a meal or FOOD INTAKE.
An antibiotic purine ribonucleoside that readily substitutes for adenosine in the biological system, but its incorporation into DNA and RNA has an inhibitory effect on the metabolism of these nucleic acids.
A methylated nucleotide base found in eukaryotic DNA. In ANIMALS, the DNA METHYLATION of CYTOSINE to form 5-methylcytosine is found primarily in the palindromic sequence CpG. In PLANTS, the methylated sequence is CpNpGp, where N can be any base.

Folate and homocysteine metabolism in copper-deficient rats. (1/254)

To investigate the effect of copper deficiency on folate and homocysteine metabolism, we measured plasma, red-cell and hepatic folate, plasma homocysteine and vitamin B-12 concentrations, and hepatic methionine synthase activities in rats. Two groups of male Sprague-Dawley rats were fed semi-purified diets containing either 0. 1 mg (copper-deficient group) or 9.2 mg (control group) of copper per kg. After 6 weeks of dietary treatment, copper deficiency was established as evidenced by markedly decreased plasma and hepatic copper concentrations in rats fed the low-copper diet. Plasma, red-cell, hepatic folate, and plasma vitamin B-12 concentrations were similar in both groups, whereas plasma homocysteine concentrations in the copper-deficient group were significantly higher than in the control group (P<0.05). Copper deficiency resulted in a 21% reduction in hepatic methionine synthase activity as compared to the control group (P<0.01). This change most likely caused the increased hepatic 5-methyltetrahydrofolate and plasma homocysteine concentrations in the copper-deficient group. Our results indicate that hepatic methionine synthase may be a cuproenzyme, and plasma homocysteine concentrations are influenced by copper nutriture in rats. These data support the concept that copper deficiency can be a risk factor for cardiovascular disease.  (+info)

Co-ordinate variations in methylmalonyl-CoA mutase and methionine synthase, and the cobalamin cofactors in human glioma cells during nitrous oxide exposure and the subsequent recovery phase. (2/254)

We investigated the co-ordinate variations of the two cobalamin (Cbl)-dependent enzymes, methionine synthase (MS) and methylmalonyl-CoA mutase (MCM), and measured the levels of their respective cofactors, methylcobalamin (CH3Cbl) and adenosylcobalamin (AdoCbl) in cultured human glioma cells during nitrous oxide exposure and during a subsequent recovery period of culture in a nitrous oxide-free atmosphere (air). In agreement with published data, MS as the primary target of nitrous oxide was inactivated rapidly (initial rate of 0.06 h(-1)), followed by reduction of CH3Cbl (to <20%). Both enzyme activity and cofactor levels recovered rapidly when the cells were subsequently cultured in air, but the recovery was completely blocked by the protein-synthesis inhibitor, cycloheximide. During MS inactivation, there was a reduction of cellular AdoCbl and holo-MCM activity (measured in the absence of exogenous AdoCbl) to about 50% of pre-treatment levels. When the cells were transferred to air, both AdoCbl and holo-MCM activity recovered, albeit more slowly than the MS system. Notably, the regain of the holo-MCM and AdoCbl was enhanced rather than inhibited by cycloheximide. These findings confirm irreversible damage of MS by nitrous oxide; hence, synthesis of the enzyme is required to restore its activity. In contrast, restoration of holo-MCM activity is only dependent on repletion of the AdoCbl cofactor. We also observed a synchronous fluctuation in AdoCbl and the much larger hydroxycobalamin pool during the inactivation and recovery phase, suggesting that the loss and repletion of AdoCbl reflect changes in intracellular Cbl homoeostasis. Our data demonstrate that the nitrous oxide-induced changes in MS and CH3Cbl are associated with reversible changes in both MCM holoactivity and the AdoCbl level, suggesting co-ordinate distribution of Cbl cofactors during depletion and repletion.  (+info)

Reversal of ethanol-induced hepatic steatosis and lipid peroxidation by taurine: a study in rats. (3/254)

Alcohol (ethanol) was administered chronically to female Sprague-Dawley rats in a nutritionally adequate, totally liquid diet for 28 days. This resulted in significant hepatic steatosis and lipid peroxidation. When taurine was administered for 2 days following alcohol withdrawal it was found to reduce alcohol-induced lipid peroxidation and completely reversed hepatic steatosis. The reversal of hepatic steatosis was demonstrated both biochemically and histologically. Two days following alcohol withdrawal, the apparent activity of the alcohol-inducible form of cytochrome P450 (CYP2E1) was unchanged although total cytochrome P450 content was increased. In addition, alcohol significantly inhibited hepatic methionine synthase activity and increased homocysteine excretion in urine. Although alcohol did not affect the urinary excretion of taurine (a non-invasive marker of liver damage), levels of serum and hepatic taurine were markedly raised in animals given taurine following their treatment with alcohol, compared to animals given taurine alone. There was evidence of slight bile duct injury in animals treated with alcohol and with alcohol followed by taurine, as indicated by raised serum alkaline phosphatase (ALP) and cholesterol. Aspartate aminotransferase (AST) was also slightly raised. The effects of taurine on reversing hepatic steatosis may be due to the enhanced secretion of hepatic triglycerides. It is suggested that increased bile flow as a result of taurine treatment may have contributed to the removal of lipid peroxides. These in-vivo findings demonstrate for the first time that hepatic steatosis and lipid peroxidation, occurring as a result of chronic alcohol consumption, can be reversed by administration of taurine to rats for 2 days.  (+info)

A new class of cobalamin transport mutants (btuF) provides genetic evidence for a periplasmic binding protein in Salmonella typhimurium. (4/254)

No periplasmic binding protein has been demonstrated for the ATP-binding cassette (ABC)-type cobalamin transporter BtuCD. New mutations (btuF) are described that affect inner-membrane transport. The BtuF protein has a signal sequence and resembles the periplasmic binding proteins of several other ABC transporters.  (+info)

Molecular basis for methionine synthase reductase deficiency in patients belonging to the cblE complementation group of disorders in folate/cobalamin metabolism. (5/254)

Methionine synthase reductase (MSR) deficiency is an autosomal recessive disorder of folate/cobalamin metabolism leading to hyperhomocysteinemia, hypo- methioninemia and megaloblastic anemia. Deficiency in MSR activity occurs as the result of a defect in the MSR enzyme, which is required for the reductive activation of methionine synthase (MS). MS itself is responsible for the folate/cobalamin-dependent conversion of homo- cysteine to methionine. We have recently cloned the cDNA corresponding to the MSR protein, a novel member of the ferredoxin-NADP(+)reductase (FNR) family of electron transferases. We have used RT-PCR, heteroduplex, single-strand conformation poly- morphism (SSCP) and DNA sequence analyses to reveal 11 mutations in eight patients from seven families belonging to the cblE complementation group of patients of cobalamin metabolism that is defective in the MSR protein. The mutations include splicing defects leading to large insertions or deletions, as well as a number of smaller deletions and point mutations. Apart from an intronic substitution found in two unrelated patients, the mutations appear singular among individuals. Of the eleven, three are nonsense mutations, allowing for the identification of two patients for whom little if any MSR protein should be produced. The remaining eight involve point mutations or in-frame disruptions of the coding sequence and are distributed throughout the coding region, including proposed FMN, FAD and NADPH binding sites. These data demonstrate a unique requirement for MSR in the reductive activation of MS.  (+info)

A polymorphism of the methionine synthase gene: association with plasma folate, vitamin B12, homocyst(e)ine, and colorectal cancer risk. (6/254)

We previously reported (J. Chen et al., Cancer Res., 56: 4862-4864, 1996; J. Ma et al., Cancer Res., 57: 1098-1102, 1997) that a 5,10-methylenetetrahydrofolate reductase (MTHFR) polymorphism (677C-->T, ala-->val) was associated with lower risk of colorectal cancer. In this study, we examined the relationship of a polymorphism (2756A-->G, asp-->gly) in the gene (MTR) for methionine synthase, another important enzyme in the same folate/methionine/homocyst(e)ine metabolic pathway, with risk of colorectal cancer among 356 cases and 476 cancer-free controls. The frequency of the homozygous variant genotype (gly/gly) was slightly lower among cases (3%) than controls (5%). The odds ratio for the gly/gly genotype was 0.59 [95% confidence interval (CI), 0.27-1.27] compared with those with the homozygous wild type (asp/asp). There were no significant differences in plasma levels of folate, vitamin B12, and homocyst(e)ine (tHcy) among the MTR genotypes, in contrast to the MTHFR polymorphism. However, similar to the interaction observed for the MTHFR polymorphism among men who consumed less than 1 alcoholic drink/day, those with the gly/gly genotype had a lower risk of colorectal cancer with an odds ratio of 0.27 (95% CI, 0.09-0.81) compared with those with the asp/asp genotype. The possible association of the MTR polymorphism with lower risk of colorectal cancer especially among those with low alcohol consumption, in the same direction as for the MTHFR polymorphism, is intriguing. However, our study had limited statistical power because of the low frequency of the MTR variant genotype, which is reflected in the wide CIs. Hence, these findings need to be confirmed in larger populations.  (+info)

Heterologous high level expression, purification, and enzymological properties of recombinant rat cobalamin-dependent methionine synthase. (7/254)

Rat methionine synthase was expressed chiefly as apoenzyme in recombinant baculovirus-infected insect cells (Yamada, K., Tobimatsu, T., and Toraya, T. (1998) Biosci. Biotech. Biochem. 62, 2155-2160). The apoenzyme produced was very unstable, and therefore, after complexation with methylcobalamin, the functional holoenzyme was purified to homogeneity. The specific activity and apparent K(m) values for substrates were in good agreement with those obtained with purified rat liver enzyme. The electronic spectrum of the purified recombinant enzyme resembled that of cob(II)alamin and changed to a methylcobalamin-like one upon incubation of the enzyme with titanium(III) and S-adenosylmethionine. The rate of oxidative inactivation of the enzyme in the absence of S-adenosylmethionine was slower with a stronger reducing agent like titanium(III). The nucleotide moiety, especially the phosphodiester group, was shown to play an important role in the binding of the coenzyme to apoprotein and thus for catalysis. Upon incubation with the apoenzyme in the absence of a reducing agent, cyano- and aquacobalamin were not effective or were effective only slightly in reconstituting holoenzyme. Ethyl- and propylcobalamin formed inactive complexes with apoenzyme, which were converted to holoenzyme by photolytic activation. Adenosylcobalamin was not able to form a complex with apoenzyme, which was convertible to holoenzyme by photoirradiation.  (+info)

Characterization and functional expression of cDNAs encoding methionine-sensitive and -insensitive homocysteine S-methyltransferases from Arabidopsis. (8/254)

Plants synthesize S-methylmethionine (SMM) from S-adenosylmethionine (AdoMet), and methionine (Met) by a unique reaction and, like other organisms, use SMM as a methyl donor for Met synthesis from homocysteine (Hcy). These reactions comprise the SMM cycle. Two Arabidopsis cDNAs specifying enzymes that mediate the SMM --> Met reaction (SMM:Hcy S-methyltransferase, HMT) were identified by homology and authenticated by complementing an Escherichia coli yagD mutant and by detecting HMT activity in complemented cells. Gel blot analyses indicate that these enzymes, AtHMT-1 and -2, are encoded by single copy genes. The deduced polypeptides are similar in size (36 kDa), share a zinc-binding motif, lack obvious targeting sequences, and are 55% identical to each other. The recombinant enzymes exist as monomers. AtHMT-1 and -2 both utilize l-SMM or (S,S)-AdoMet as a methyl donor in vitro and have higher affinities for SMM. Both enzymes also use either methyl donor in vivo because both restore the ability to utilize AdoMet or SMM to a yeast HMT mutant. However, AtHMT-1 is strongly inhibited by Met, whereas AtHMT-2 is not, a difference that could be crucial to the control of flux through the HMT reaction and the SMM cycle. Plant HMT is known to transfer the pro-R methyl group of SMM. This enabled us to use recombinant AtHMT-1 to establish that the other enzyme of the SMM cycle, AdoMet:Met S-methyltransferase, introduces the pro-S methyl group. These opposing stereoselectivities suggest a way to measure in vivo flux through the SMM cycle.  (+info)

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Methylenetetrahydrofolate reductase and cobalamin-dependent methionine synthase catalyze the penultimate and ultimate steps in the biosynthesis of methionine in prokaryotes, and are required for the r
Methionine synthase, a vitamin B12-dependent enzyme, plays an important role in folate metabolism (1) . It catalyzes the transfer of a methyl group from 5-methyltetrahydrofolate to homocysteine, producing methionine and tetrahydrofolate. Methionine synthase is critical for maintaining adequate intracellular methionine, an essential amino acid and the precursor of SAM.4 SAM is a crucial methyl group donor involved in over 100 methylation reactions including DNA methylation. Hypomethylation of the promoter regions of proto-oncogenes ,(2) or hypermethylation of these regions of tumor suppressor genes (3) may cause selective growth and transformation of cells. De novo methylation of CpG islands within the promoter regions of growth-regulatory genes, which may inactivate their transcription, is frequently observed in colonic tumors (4) . Methionine synthase is also essential for maintaining adequate intracellular folate pools and ensuring that homocysteine concentrations do not reach toxic levels. ...
TY - JOUR. T1 - Methionine Synthase D919G Polymorphism, Folate Metabolism, and Colorectal Adenoma Risk. AU - Goode, Ellen L.. AU - Potter, John D.. AU - Bigler, Jeannette. AU - Ulrich, Cornelia M.. PY - 2004/1/1. Y1 - 2004/1/1. N2 - Methionine synthase [5-methyltetrahydrofolate-homocysteine S-methyltransferase (MTR)] is involved in folate-mediated one-carbon metabolism, a pathway known to play a role in colorectal carcinogenesis. We investigated whether the MTR D919G polymorphism was associated with risk of colorectal adenoma in a colonoseopy-based study of 513 cases and 609 controls from Minneapolis, MN. Adenoma risk appeared nonsignificantly increased among women with DG or GG genotype [adjusted odds ratio (OR) versus DD, 1.4; 95% confidence interval (CI), 0.9-2.1] but not men (OR, 1.0; 95% CI, 0.7-1.5). An interaction with methionine intake was observed among women, such that low versus high intake was associated with a 2.3-fold increased risk only among those with DG or GG genotype (95% CI, ...
In this study, we examined polymorphisms in the rate-limiting enzyme MTHFR and a polymorphism in an associated enzyme, MTR. Both enzymes are important in one-carbon metabolism. None of these polymorphisms, however, were associated with an alteration in breast cancer risk in either premenopausal or postmenopausal women. We did find some evidence of an interaction of MTHFR C677T and alcohol with risk of breast cancer among postmenopausal women with the homozygote variant genotype (TT), but there was no evidence of that interaction for the other two polymorphisms.. The biochemical reactions involved in one-carbon metabolism are necessary for the synthesis of purines and pyrimidines as well as for the formation of S-adenosylmethionine, important for the methylation of substrates such as DNA and therefore essential to gene regulation (4). The fundamental acceptor molecule for one-carbon metabolism is folate (4). Alcohol consumption can affect the intake, absorption, activation, and storage of folate ...
Coronary artery disease (CAD) is an important cause of morbidity and mortality in cardiac patients. Atherosclerosis, as the underlying pathology of coronary heart disease, is a common multifactorial disorder with both genetic and environmental components (1). Smoking and high blood pressure are the main risk factors for cardiovascular diseases.. Lately, plasma homocysteine has been introduced as a risk factor for CAD (1, 2). It is reported that mutations in 100 genes result in the development of CAD (3). Mutations in genes affecting plasma homocysteine level may be associated with CAD. The association of CAD with single nucleotide polymorphisms (SNPs) in 2 important genes, ie, 10-methylene tetrahydrofolate reductase (MTHFR) and methyltetrahydrofolate-homocysteine methyltransferase (MTR), has been reported in the literature. Several studies on different populations have demonstrated a significant association between polymorphisms, rs1801131 and rs1805087, and development of CAD (4, 5); ...
This article was originally written in March of 1998 and appeared in RWJ Today during my first year of medical school. It is a good glimpse into my thinking at that time and the research background that I had come from at Cornell University:. The connection between blood cholesterol levels, dietary saturated fats, and vascular pathologies such as coronary artery disease and stroke is well known. Less well known, is the link between blood homocysteine levels and these same vascular diseases.. Homocysteine is an amino acid that is normally remethylated by methionine synthase, a vitamin B12 and folate-dependent enzyme, to produce methionine. Methionine is then utilized for protein synthesis directly, and indirectly as S-adenosylmethionine, for a multitude of methylation reactions throughout the cell. Disruption in methionine synthase activity, either by genetic mutation or cofactor deficiency, causes abnormal buildup of plasma homocysteine levels.. An alternative route for homocysteine disposal is ...
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जाता; काळजाच्या शिरांक हो रोग जातकच, काळजाक जाय तितलें रगत पावना आनी ताका लागून छातयेंत दुखूंक लागता. ह्या लक्षणांक ह्र्दशुल (angina) अशें म्हण्टात. जेन्ना शिरेंतल्यान रगत वचपाचें सामकेंच बंद जाता, तेन्ना चड दुखूंक लागता, घाम येता आनी रक्तदाब (blood pressure) देंवत वा चडटा. हाकाच काळजाचो ॲटॅक अशें म्हण्टात. ही पीडा चड घातक आशिल्ल्यान, हाचेर सुरवातीचो उपचार हॉस्पिटलांत जाल्लो बरो आसता. पयल्या ...
TY - JOUR. T1 - Hepatic betaine-homocysteine methyltransferase and methionine synthase activity and intermediates of the methionine cycle are altered by choline supply during negative energy balance in Holstein cows. AU - Coleman, Danielle N.. AU - Vailati-Riboni, M.. AU - Elolimy, Ahmed A.. AU - Cardoso, Felipe C.. AU - Rodriguez-Zas, Sandra L.. AU - Miura, Makoto. AU - Pan, Yuan Xiang. AU - Loor, Juan J.. PY - 2019/9. Y1 - 2019/9. N2 - Although choline requirements are unknown, enhanced postruminal supply may decrease liver triacylglycerol (TAG) storage and increase flux through the methionine cycle, helping cows during a negative energy balance (NEB). The objective was to investigate effects of postruminal choline supply during NEB on hepatic activity of betaine-homocysteine methyltransferase (BHMT), methionine synthase (MTR), methionine adenosyltransferase, transcription of enzymes, and metabolite concentrations in the methionine cycle. Ten primiparous rumen-cannulated Holstein cows (158 ± ...
Key enzyme in methionine and folate homeostasis responsible for the reactivation of methionine synthase (MTR/MS) activity by catalyzing the reductive methylation of MTR-bound cob(II)alamin. Cobalamin (vitamin B12) forms a complex with MTR to serve as an intermediary in methyl transfer reactions that cycles between MTR-bound methylcob(III)alamin and MTR bound-cob(I)alamin forms, and occasional oxidative escape of the cob(I)alamin intermediate during the catalytic cycle leads to the inactive cob(II)alamin species. The processing of cobalamin in the cytosol occurs in a multiprotein complex composed of at least MMACHC, MMADHC, MTRR and MTR which may contribute to shuttle safely and efficiently cobalamin towards MTR in order to produce methionine (By similarity). Also necessary for the utilization of methyl groups from the folate cycle, thereby affecting transgenerational epigenetic inheritance (By similarity). Also acts as a molecular chaperone for methionine synthase by stabilizing apoMTR and incorporating
This gene encodes a member of the ferredoxin-NADP(+) reductase (FNR) family of electron transferases. This protein functions in the synthesis of methionine by regenerating methionine synthase to a functional state. Because methionine synthesis requires methyl-group transfer by a folate donor, activity of the encoded enzyme is important for folate metabolism and cellular methylation. Mutations in this gene can cause homocystinuria-megaloblastic anemia, cbl E type. Alternative splicing of this gene results in multiple transcript variants. [provided by RefSeq, Dec 2015 ...
Vitamin B12 is a complex organometallic cofactor associated with three subfamilies of enzymes: the adenosylcobalamin-dependent isomerases, the methylcobalamin-dependent methyltransferases, and the dehalogenases. Different chemical aspects of the cofactor are exploited during catalysis by the isomerases and the methyltransferases. Thus, the cobalt-carbon bond ruptures homolytically in the isomerases, whereas it is cleaved heterolytically in the methyltransferases. The reaction mechanism of the dehalogenases, the most recently discovered class of B12 enzymes, is poorly understood. Over the past decade our understanding of the reaction mechanisms of B12 enzymes has been greatly enhanced by the availability of large amounts of enzyme that have afforded detailed structure-function studies, and these recent advances are the subject of this review.
What Is It?. Methylcobalamin is an activated, highly bioavailable form of vitamin B12, which acts as the principal circulating form of cobalamin in the body. It is available in liquid and capsule form.*. Uses For Methylcobalamin. Nervous System Health: In recent studies, methylcobalamin has demonstrated an enhanced ability to support neurological function. This form of vitamin B12 promotes protein synthesis for maintaining healthy nerve cells and myelin. Methylcobalamin may also help to moderate levels of glutamate in the brain, encouraging healthy brain cell activity, as well as memory, mood, and cognitive function. In general, vitamin B12 works with folate to promote DNA and red blood cell health. Additionally, vitamin B12 is an important cofactor for energy metabolism and a vital component of the methionine synthase pathway, which supports healthy homocysteine metabolism and S-adenosylmethionine (SAMe) production.*. What Is The Source?. Pure Encapsulations methylcobalamin is produced from ...
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PubMed journal article Polymorphisms in the methylenetetrahydrofolate reductase and methionine synthase reductase genes and homocysteine levels in Brazilian childre were found in PRIME PubMed. Download Prime PubMed App to iPhone or iPad.
Diatoms are responsible for ∼40% of marine primary production and are key players in global carbon cycling. There is mounting evidence that diatom growth is influenced by cobalamin (vitamin B12) availability. This cobalt-containing micronutrient is only produced by some bacteria and archaea but is required by many diatoms and other eukaryotic phytoplankton. Despite its potential importance, little is known about mechanisms of cobalamin acquisition in diatoms or the impact of cobalamin scarcity on diatom molecular physiology. Proteomic profiling and RNA-sequencing transcriptomic analysis of the cultured diatoms Phaeodactylum tricornutum and Thalassiosira pseudonana revealed three distinct strategies used by diatoms to cope with low cobalamin: increased cobalamin acquisition machinery, decreased cobalamin demand, and management of reduced methionine synthase activity through changes in folate and S-adenosyl methionine metabolism. One previously uncharacterized protein, cobalamin acquisition ...
The inhalation of Nitrous Oxide is NOT RECOMMENDED. The preparation of the gas as detailed elsewhere on this site is extremely dangerous (propensity of ammonium nitrate to detonate), and produces an impure gas which will poison you. Nitrous users who inhale from bottled gas risk frozen vocal chords, hypoxic irreversible brain damage, induced neuropathy and myeloneuropathy, inhibition of methionine synthase activity because of interaction with cobalt in vitamin B12, death by suffocation, unconciousness and laughter ...
Objective: This study was aimed to evaluate the Methionine synthase reductase (MTRR) A66G mutation in Yadav and Scheduled Caste (SC) population of Uttar Pradesh. Materials and Methods: Blood samples were collected from 100 subjects after taking infor
Homocysteine S -methyltransferases (HMTs, EC catalyze the conversion of homocysteine to methionine using S -methylmethionine or S -adenosylmethionine as the methyl donor. HMTs play an important role in methionine biosynthesis and are widely distributed among microorganisms, plants, and animals. Additionally, HMTs play a role in metabolite repair of S -adenosylmethionine by removing an inactive diastereomer from the pool. The mmuM gene product from Escherichia coli is an archetypal HMT family protein and contains a predicted Zn-binding motif in the enzyme active site. Here we present X-ray structures for MmuM in oxidized, apo, and metallated forms, representing the first such structures for any member of the HMT family. The structures reveal a metal/substrate binding pocket distinct from those in related enzymes. The presented structure analysis and modelling of co-substrate interactions provide valuable insight into the function of MmuM in both methionine biosynthesis and cofactor ...
Methylcobalamin is a more predominant and active form of Vitamin B-12. Regular Vitamin B-12 supplements must be converted in the body to Methylcobalamin before they can provide any benefits - taking Methylcobalamin allows you to bypass this step for quicker absorption. B-12 may not be as readily absorbable as you age, so older adults may especially benefit from taking a Methylcobalamin supplement. This biologically active form of B-12 promotes heart health and energy metabolism. Our vegetarian-friendly microlozenges supply you with a high-potency source of B-12.. ...
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PRODUCT DESCRIPTION Essential for Energy Production* Methylcobalamin Hypoallergenic Vitamin B-12 is necessary for the production of energy from fats and proteins and is well known for its critical role in DNA synthesis, as well as in homocysteine metabolism.* Methylcobalamin is the co-enzyme form of vitamin B-12 that h
There are some compelling reasons to question the routine use of nitrous oxide (N2O), also known as laughing gas. Despite being the first anaesthetic drug introduced, and still widely used, there is sufficient doubt as to the risk-benefit profile.. There is strong evidence that N2O is a major risk factor for postoperative nausea and vomiting. It is clear that (even) brief exposure to N2O impairs methionine synthetase, an enzyme required for DNA production, red and white blood cell formation. Tissue hypoxia may be more common. These adverse effects are enhanced in sick patients (ie. those at highest risk, increased hospital length of stay and healthcare expenditure), and will be more likely in longer surgery. The extent of wound infection and cardiac morbidity associated with N2O is not known.. Large outcome trial data are lacking. When considering its widespread use in about 90% of all surgery around the world, small differences in outcome would have major implications for healthcare ...
Pregabalin+Mecobalamin can reduce the release of neurotransmitters and promotes regeneration of neuronal myelin sheath. Pregabalin possess analgesic property and reduce neuropathy-related pain symptoms. Mecobalamin is a cofactor of methionine synthase for the transfer of methyl groups to generate methionine from homocysteine. Elevated level of homocysteine is a predominant risk factor of CAD. Methionine can be converted into s-adenosylmethionine, which involve in methylation reactions related to reduction of depressive disorders.. Pregabalin selectively binds to voltage-dependent calcium channel and reduce the release of substance P, glutamate, calcitonin-related peptide and norepinephrine. Contrary to other anxiolytics, Pregabalin neither binds to GABA receptors nor increase/influence GABA currents or metabolism.. Pharmacokinetics ...
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PRODUCT DESCRIPTION Essential for Energy Production* Methylcobalamin Hypoallergenic Vitamin B-12 is necessary for the production of energy from fats and proteins and is well known for its critical role in DNA synthesis, as well as in homocysteine metabolism.* Methylcobalamin is the co-enzyme form of vitamin B-12 that h
Methylcobalamin is the metabolically active form of B-12. Tired and exhausted, the needed incitement is missing? B12 as methylcobalamin is an excellent supplement for you.. ...
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Diversity of protein and mRNA forms of mammalian methionine sulfoxide reductase B1 due to intronization and protein processing. PLoS One. 2010 Jul 09; 5(7):e11497 ...
Background: Polymorphisms of genes encoding enzymes involved in folate metabolism have long been hypothesized to be maternal risk factors for Down syndrome, however, results are conflicting and inconclusive.. Aim of the study: To analyze the effect of methionine synthase (MTR) A2756G, and reduced folate carrier (RFC1) A80G gene polymorphisms on the maternal risk for DS.. Patients: This study was conducted in the Medical Genetics Center, Ain-Shams University hospitals, on a total of 170 mothers of children, diagnosed with Down syndrome, who were attending the center. Eighty-five control mothers were also enrolled in the study.. Methods: Genotype analyses were performed using PCR-RFLP to detect RFC1A80G and MTRA2756G gene polymorphisms in all case and control mothers.. Results: Comparing RFC1A80G genotype frequency between both groups revealed, that the frequency of the AA genotype in case mothers (94.11%) is highly significantly (p, 0.001) greater than its frequency in control mothers (74.11%), ...
Polymorphisms in the methylenetetrahydrofolate reductase (MTHFR), methionine synthase reductase (MTRR) and cystathionine β-synthase (CBS) genes, involved in the intracellular metabolism of homocysteine (Hcy), can result in hyperhomocysteinemia. The objective of this study was to evaluate prevalence estimates of CBS T833C, G919A and the insertion of 68-bp (844ins68) polymorphisms and their correlation with Hcy, folate and B12 in 220 children previously genotyped for MTHFR C677T, A1298C, and MTRR A66G. The prevalence of heterozygote children for 844ins68 was 19.5%. The T833C CBS mutation was identified in association with 844ins68 in all the carriers of the insertion. Genotyping for CBS G919A mutation showed that all the children presented the GG genotype. Analysis of Hcy, B12 and folate, according to the combination of the different genotypes of the C677T and A1298C MTHFR, A66G MTRR, and 844ins68 CBS showed that the 677TT/1298AA/68WW genotype is associated with an increase in Hcy, when compared ...
A cobalamin-dependent N5-methyltetra-hydrofolate-homocysteine methyltransferase (methyl-transferase) was demonstrated in unfractioned extracts of human normal and leukemia leukocytes. Activity was substantially reduced in the absence of an added cobalamin derivative. Presumably, this residual activity reflects the endogeneous level of holoenzyme. Enzyme activity was notably higher in lymphoid cells than in myeloid cells. Thus, mean specific activities (+/-SD) were: chronic lymphocytic leukemia lymphocytes, 2.15+/-1.16; normal lymphocytes, 0.91+/-0.59; normal mature granulocytes, 0.15+/-0.10; chronic myelocytic leukemia granulocytes, barely detectable activity. Properties of leukocytes enzymes resembled those of methyltransferases previously studied in bacteria and other animal cells. Granulocytes and chronic myelocytic leukemia cells contain a factor or factors that inhibits Escherichia coli enzyme. The data suggest that the prominence of this cobalamin-dependent enzyme in lymphocytes and other ...
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Methylenetetrahydrofolate reductase required to generate the methyl groups necessary for methionine synthetase to convert homocysteine to methionine.
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Methylcobalamin Max is a higher concentration of B12 at 10,000 mcg/ml, allowing for subcutaneous administration. Methylcobalamin is the most active form of the B12 family. This is what the body converts Cyanocobalamin into, so it is more readily available to the body.. This form of B12 is better absorbed than Cyanocobalamin because it is more bioavailable. Vitamin B12 is an essential component for proper digestion and absorption of foods and for normal metabolism of carbohydrates, and fat. It aids in maintaining healthy nerve cells and red blood cells and is needed to make DNA. Vitamin B12 is also involved in homocysteine metabolism and plays a critical role in proper energy metabolism, immune function, and nerve function. Several disorders have recently been linked to possible vitamin B12 deficiencies. Methylcobalamin also interacts differently with certain neurotransmitters within the brain and appears to be helpful in treating Autism.. *** This product is not intended to diagnose, treat, ...
Sigma-Aldrich offers abstracts and full-text articles by [Halina Jurkowska, Julie Niewiadomski, Lawrence L Hirschberger, Heather B Roman, Kevin M Mazor, Xiaojing Liu, Jason W Locasale, Eunkyue Park, Martha H Stipanuk].
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Betaine-homocysteine S-methyltransferase GRCh38: Ensembl release 89: ENSG00000116984 - Ensembl, May 2017 GRCm38: Ensembl ... Zhu H, Wicker NJ, Shaw GM, Lammer EJ, Hendricks K, Suarez L, Canfield M, Finnell RH (March 2003). "Homocysteine remethylation ... Methionine synthase also known as MS, MeSe, MetH is responsible for the regeneration of methionine from homocysteine. In humans ... Methionine synthase catalyzes the final step in the regeneration of methionine (Met) from homocysteine (Hcy). The overall ...
Chronic homocysteine elevation increases s-adenosyl-L-homocysteine levels, consequently inhibiting methyltransferase activity ... Prenatal diagnosis of this condition is possible using [14C] methyltetrahydrofolate. Mutation analysis in native chorionic ... Homocysteine, a sulfur based amino acid is the main product of methionine demethylation. Elevated homocysteine is an ... A major product of methionine demethylation is homocysteine. Remethylation of homocysteine occurs via a cobalamin dependent ...
PRMT6: Protein arginine methyltransferase 6. *PSRC1: Proline/serine-rich coiled-coil protein 1 ... doi:10.1186/gb-2010-11-5-206. PMC 2898077. PMID 20441615.. *^ "Statistics & Downloads for chromosome 1". HUGO Gene Nomenclature ... Chromosome 1 spans about 249 million nucleotide base pairs, which are the basic units of information for DNA.[5] It represents ... FRA1J encoding protein Fragile site, 5-azacytidine type, common, fra(1)(q12) ...
Ang kromosomang 1 o kulaylawas[1] na 1 (Ingles: Chromosome 1) ang pagtatakda ng pinakamalaking kromosomang pantao. Ang mga tao ay may dalawang mga kopya ng kromosomang 1 gaya ng sa lahat ng mga autosoma na hindi mga kromosomang kasarian. Ang kromosomang 1 ay sumasaklaw sa mga 247 milyong mga nucleotide na mga base na pares na mga pundamental na unit ng impormasyon para sa DNA. [2] It represents about 8% of the total DNA in human cells.[3]. Ang pagtukoy ng mga gene sa bawat kromosoma ay isang aktibong sakop ng henetikong pagsasaliksik. Ang kromosomang 1 ay kasalukuyang pinaniniwalaang may 4,220 gene na lappas sa nakaraang mga hula batay sa sukat nito. [2] Ito ang huling nakumpletong kromosoma na sinekwensiya pagkatapos ng dalawang dekada pagkatapos simulan ang proyektong genome ng tao.. ...
... may refer to: 5-methyltetrahydrofolate-homocysteine methyltransferase reductase, a human gene Memory Type Range Registers ...
Changes to chromosome 5 include an extra segment of the short (p) or long (q) arm of the chromosome in each cell (partial ... Chromosome 5 spans about 181 million base pairs (the building blocks of DNA) and represents almost 6% of the total DNA in cells ... Chromosome 5 is the 5th largest human chromosome, yet has one of the lowest gene densities. This is partially explained by ... Chromosome 5 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. ...
... vitamer is one of two active coenzymes used by vitamin B12-dependent enzymes and is the specific vitamin B12 form used by 5- ... methyltetrahydrofolate-homocysteine methyltransferase (MTR), also known as methionine synthase.[citation needed] ...
Canada 5-Methyltetrahydrofolate-homocysteine methyltransferase, or Methionine synthase, an enzyme responsible for the ...
Protein arginine methyltransferase 6 PSRC1: Proline/serine-rich coiled-coil protein 1 RAD54L: RAD54-like RAP1A (1p13) RBM15 ( ... 11 (5): 206. doi:10.1186/gb-2010-11-5-206. PMC 2898077. PMID 20441615. "Statistics & Downloads for chromosome 1". HUGO Gene ... TRE-CTC1-5: Transfer RNA-Glu (CTC) 1-5 TRP (1q31) UAP1: UDP-N-acetylhexosamine pyrophosphorylase USH2A: Usher syndrome 2A ( ... 5-azacytidine type, common, fra(1)(q12) GAS5 (1q25) GBA: glucosidase, beta; acid (includes glucosylceramidase) (gene for ...
SAM is converted to S-Adenosyl homocysteine (SAH) during this process. The breaking of the SAM-methyl bond and the formation of ... Methanol, methyl tetrahydrofolate, mono-, di-, and trimethylamine, methanethiol, methyltetrahydromethanopterin, and ... These types include protein methyltransferases, DNA/RNA methyltransferases, natural product methyltransferases, and non-SAM ... Examples include: Catechol-O-methyltransferase DNA methyltransferase Histone methyltransferase 5-Methyltetrahydrofolate- ...
PRMT6 protein arginine methyltransferase 6 [ Homo sapiens (human) ]». Gene. NCBI. 8. juni 2017. Henta 26. juni 2017.. ... Am J Med Genet 42 (5): 728-32. PMID 1632448. doi:10.1002/ajmg.1320420521.. CS1 maint: Multiple names: authors list (link) ... Science 333 (6048): 1453-5. PMC 3170506. PMID 21817013. doi:10.1126/science.1210557.. CS1 maint: Explicit use of et al. (link) ... DPH5 diphthamide biosynthesis 5 [ Homo sapiens (human) ]». Gene. NCBI. 4. juni 2017. Henta 26. juni 2017.. ...
Other cobalamin-requiring methyltransferase enzymes are also known in bacteria, such as Me-H4-MPT, coenzyme M methyltransferase ... van der Put NM, van Straaten HW, Trijbels FJ, Blom HJ (April 2001). "Folate, homocysteine and neural tube defects: an overview ... Methyltransferases Methyl (-CH3) group transfers between two molecules. These use MeB12 (methylcobalamin) form of the vitamin. ... Methionine synthase, coded by MTR gene, is a methyltransferase enzyme which uses the MeB12 and reaction type 2 to transfer a ...
10-methyltetrahydrofolate; BAX: Bcl-2-associated X protein; BHMT: betaine-homocysteine S-methyltransferase; CBS: cystathionine ... S-adenosyl-L-homocysteine; SAME: S-adenosyl-L-methionine; THF: tetrahydrofolate. ... 5,10-Methenyltetrahydrofolate. References[edit]. *^ "Entrez Gene: MTHFR methylenetetrahydrofolate reductase (NAD(P)H)".. .mw- ... 5,10-Methylenetetrahydrofolate (N5,N10-Methylenetetrahydrofolate; 5,10-CH2-THF) is cofactor in several biochemical reactions. ...
"Transfer of the methyl group from N5-methyltetrahydrofolates to homocysteine in Escherichia coli" (Free full text). The ... Other names in common use include tetrahydropteroyltriglutamate methyltransferase, homocysteine methylase, methyltransferase, ... homocysteine methyltransferase, cobalamin-independent methionine synthase, methionine synthase (cobalamin-independent), and ... Homocysteine is coordinated to a zinc ion, as initially suggested by spectroscopy and mutagenesis . Pejchal R, Ludwig ML ( ...
... that homocysteine can also be converted to methionine by the folate-independent enzyme betaine-homocysteine methyltransferase ( ... and recommended supplementation of methyltetrahydrofolate to potentially prevent and treat dementia (along with depression). A ... 677TT (but not 677CC/CT) individuals with lower plasma folate levels are at risk for elevated plasma homocysteine levels. In ... It does not result in thermolabile MTHFR and does not appear to affect homocysteine levels. It does, however, affect the ...
... histamine N-methyltransferase MeSH D08.811.913.555.500.625 - homocysteine S-methyltransferase MeSH D08.811.913.555.500.645 - 5- ... methyltetrahydrofolate-homocysteine s-methyltransferase MeSH D08.811.913.555.500.650 - nicotinamide N-methyltransferase MeSH ... betaine-homocysteine S-methyltransferase MeSH D08.811.913.555.500.250 - catechol O-methyltransferase MeSH D08.811.913.555. ... histone-lysine n-methyltransferase MeSH D08.811.913.555.500.800.650 - o-6-methylguanine-DNA methyltransferase MeSH D08.811. ...
The formation of Me-CpG is catalyzed by the enzyme DNA methyltransferase. In mammals, DNA methylation is common in body cells, ... Methionine synthase regenerates methionine (Met) from homocysteine (Hcy). The overall reaction transforms 5- ... methyltetrahydrofolate (N5-MeTHF) into tetrahydrofolate (THF) while transferring a methyl group to Hcy to form Met. Methionine ... This process, catalyzed by enzymes such as caffeoyl-CoA O-methyltransferase, is a key reaction in the biosynthesis of lignols, ...
S-adenosyl-L-homocysteine + sarcosine Thus, the two substrates of this enzyme are S-adenosyl methionine and glycine, whereas ... Other names in common use include glycine methyltransferase, S-adenosyl-L-methionine:glycine methyltransferase, and GNMT. This ... In enzymology, a glycine N-methyltransferase (EC is an enzyme that catalyzes the chemical reaction S-adenosyl-L- ... Pakhomova S, Luka Z, Grohmann S, Wagner C, Newcomer ME (2004). "Glycine N-methyltransferases: a comparison of the crystal ...
Homocysteine is an intermediate that is responsible for maintaining methylation reactions in critical metabolic processes. It ... Recent studies have shown that diabetic patients have decreased H3K9me3 and an increase in the Histone methyltransferase called ... This reaction is a critical step in the conversion of homocysteine to methionine. The resulting product is a methyl donor that ... After examining Type 2 diabetes patients, it was found that levels of homocysteine were exceptionally high when compared to ...
Additionally, a defect in homocysteine methyltransferase or a deficiency of Vitamin B12 may lead to a so-called "methyl-trap" ... measured as methyltetrahydrofolate (in practice, "folate" refers to all derivatives of folic acid, but methylhydrofolate is the ... Plasma total homocysteine is only measured in special circumstances. A level above 15 μmol/l could be indicative of a folate ... High homocysteine levels in the blood can lead to vascular injuries by oxidative mechanisms which can contribute to cerebral ...
... can be recycled into methionine. This process uses N5-methyl tetrahydrofolate as the methyl donor and cobalamin ( ... DNA methyltransferase as an intermediate acceptor in the process of DNA methylation). The adenosine is then hydrolyzed to yield ... Homocysteine MS Spectrum Homocysteine at Lab Tests Online Homocysteine: analyte monograph[permanent dead link] - The ... Homocysteine also acts as an allosteric antagonist at Dopamine D2 receptors. It has been proposed that both homocysteine and ...
This is hydrolysed to homocysteine and adenosine by S-adenosylhomocysteine hydrolase EC and the homocysteine recycled ... DNA methyltransferase SAM-I riboswitch SAM-II riboswitch SAM-III riboswitch SAM-IV riboswitch SAM-V riboswitch SAM-VI ... that use SAM-e as a substrate produce S-adenosyl homocysteine as a product. S-Adenosyl homocysteine is a strong negative ... Methyltransferases are also responsible for the addition of methyl groups to the 2′ hydroxyls of the first and second ...
... in a reaction catalyzed by homocysteine methyltransferase, to methionine. A defect in homocysteine methyltransferase or a ... methyltetrahydrofolate (5-MTHF), a direct target of methyl donors such as S-adenosyl methionine (SAMe), recycles the inactive ... Increased homocysteine levels suggest tissue folate deficiency, but homocysteine is also affected by vitamin B12 and vitamin B6 ... Conversion of homocysteine to methionine requires folate and vitamin B12. Elevated plasma homocysteine and low folate are ...
... histamine N-methyltransferase EC thiol S-methyltransferase EC homocysteine S-methyltransferase EC ... betaine-homocysteine S-methyltransferase EC catechol O-methyltransferase EC nicotinate N-methyltransferase EC ... EC nicotinamide N-methyltransferase EC guanidinoacetate N-methyltransferase EC thetin-homocysteine S ... sterol 24-C-methyltransferase EC luteolin O-methyltransferase EC histone-lysine N-methyltransferase EC 2.1. ...
... in a reaction catalyzed by homocysteine methyltransferase, to methionine. A defect in homocysteine methyltransferase or a ... This reaction provides the largest part of the one-carbon units available to the cell.[77]Methyl tetrahydrofolate (CH3-THF, or ... Increased homocysteine levels suggest tissue folate deficiency, but homocysteine is also affected by vitamin B12 and vitamin B6 ... Varela-Moreiras G, Murphy MM, Scott JM (2009). "Cobalamin, folic acid, and homocysteine". Nutrition Reviews. 67 Suppl 1: S69- ...
... methyltetrahydrofolate homocysteine methyltransferase reductase (MTRR) A66G were shown to be positively associatiated with ... This family includes cobalamin-dependent methyltransferases such as methyltetrahydrofolate, corrinoid iron-sulfur protein ... This family includes cobalamin-dependent methyltransferases such as methyltetrahydrofolate, corrinoid iron-sulfur protein ... This family includes cobalamin-dependent methyltransferases such as methyltetrahydrofolate, corrinoid iron-sulfur protein ...
The PDB archive contains information about experimentally-determined structures of proteins, nucleic acids, and complex assemblies. As a member of the wwPDB, the RCSB PDB curates and annotates PDB data according to agreed upon standards. The RCSB PDB also provides a variety of tools and resources. Users can perform simple and advanced searches based on annotations relating to sequence, structure and function. These molecules are visualized, downloaded, and analyzed by users who range from students to specialized scientists.
5-methyltetrahydrofolate-homocysteine methyltransferase reductaseImported. ,p>Information which has been imported from another ... Annotation score:2 out of 5. ,p>The annotation score provides a heuristic measure of the annotation content of a UniProtKB ... Annotation score:1 out of 5. ,p>The annotation score provides a heuristic measure of the annotation content of a UniProtKB ... tr,F6Y2F2,F6Y2F2_MACMU 5-methyltetrahydrofolate-homocysteine methyltransferase reductase OS=Macaca mulatta OX=9544 GN=MTRR PE=4 ...
homocysteine catabolic process Source: Ensembl. *homocysteine metabolic process Source: GO_CentralInferred from biological ... 5-methyltetrahydrofolate-homocysteine methyltransferase reductaseImported. ,p>Information which has been imported from another ... Annotation score:2 out of 5. ,p>The annotation score provides a heuristic measure of the annotation content of a UniProtKB ... tr,F6UGP3,F6UGP3_MONDO 5-methyltetrahydrofolate-homocysteine methyltransferase reductase OS=Monodelphis domestica OX=13616 GN= ...
The 2756A,G variant in the gene encoding methionine synthase: its relation with plasma homocysteine levels and risk of coronary ... Gene-environment and gene-gene interaction in the determination of plasma homocysteine levels in healthy middle-aged men. ... Influence of a methionine synthase (D919G) polymorphism on plasma homocysteine and folate levels and relation to risk of ... Polymorphism of the methionine synthase gene: association with homocysteine metabolism and late-onset vascular diseases in the ...
Homocysteine-methyl tetrahydrofolate methyltransferase. *METH_HUMAN. *Methionine Synthase. *Tetrahydropteroylglutamate ... Some of the excess homocysteine is excreted in urine. Researchers have not determined how altered levels of homocysteine and ... Without functional methionine synthase, homocysteine cannot be converted to methionine. As a result, homocysteine builds up in ... Carmel R, Green R, Rosenblatt DS, Watkins D. Update on cobalamin, folate, and homocysteine. Hematology Am Soc Hematol Educ ...
MT-ND5: mitochondrially encoded NADH:ubiquinone oxidoreductase core subunit 5. *MT-ND6: mitochondrially encoded NADH:ubiquinone ... MTR: 5-methyltetrahydrofolate-homocysteine methyltransferase. *MTRR: 5-methyltetrahydrofolate-homocysteine methyltransferase ...
2015 May;208(5):241-52. doi: 10.1016/j.cancergen.2015.03.008. Epub 2015 Mar 18. Research Support, Non-U.S. Govt ... Subsequently occurring regulatory processes can induce an aberrant stimulation of DNA methyltransferase (DNMT1) as well as ... Karlic H1, Thaler R2, Gerner C3, Grunt T4, Proestling K5, Haider F2, Varga F2. ... 5. Signaling Networks Program, Division of Oncology, Department of Medicine I, Medical University Vienna, Vienna, Austria; ...
Human thiopurine methyltransferase pharmacogenetics: Gene sequence polymorphisms. Clin. Pharmacol. Ther. 62, 60-73.CrossRef ... 5.. Adam de Beaumais T., Fakhoury M., et al. 2011. Determinants of mercaptopurine toxicity in paediatric acute lymphoblastic ... 5-methyltetrahydrofolate-homocysteine methyltransferase reductase gene. NR3C1. nuclear receptor subfamily 3 group C member 1 ...
Structure Of the Pterin-Binding Domain Metr of 5- Methyltetrahydrofolate-Homocysteine Methyltransferase From Bacteroides ... Methyltetrahydrofolate-Homocysteine Methyltransferase From Bacteroides Thetaiotaomicron (pdb code 3k13). This binding sites ... Methyltetrahydrofolate-Homocysteine Methyltransferase From Bacteroides Thetaiotaomicron (pdb 3k13). ... The binding sites of Potassium atom in the structure of Structure Of the Pterin-Binding Domain Metr of 5- ...
November 18, 2016 at 5:31 PM Hi my grandson is missing .21-32 near the tip of the short arm of chromosome 1! His other ...
Homocysteine methyltransferase activity in extracts from normal, malignant and embryonic tissue culture cells. Biochem. Biophys ... Homocysteine (Hcy) is a key junction metabolite that lies at the nexus of two pathways involved in methionine (Met) and ... Sulfur amino acid metabolism: Pathways for production and removal of homocysteine and cysteine. Annu. Rev. Nutr. 24, 539-577 ( ... The precursor homocysteine is metabolized either through the methionine cycle to produce methionine or through the ...
5-methyltetrahydrofolate-homocysteine methyltransferase reductase. MGI:1891037 Go Annotations as Summary Text (Tabular View) ( ... Orthologous to human MTRR (5-methyltetrahydrofolate-homocysteine methyltransferase reductase).. Go Annotations in Tabular Form ...
methionine synthase reductase , [methionine synthase]-cobalamin methyltransferase (cob(II)alamin reducing) , methionine ... MTRR ELISA Kit (5-Methyltetrahydrofolate-Homocysteine Methyltransferase Reductase) ELISA Kit MTRR Reactivity: Rat Colorimetric ... MTRR ELISA Kit (5-Methyltetrahydrofolate-Homocysteine Methyltransferase Reductase) ELISA Kit MTRR Reactivity: Cow Colorimetric ... MTRR ELISA Kit (5-Methyltetrahydrofolate-Homocysteine Methyltransferase Reductase) ELISA Kit MTRR Reactivity: Mouse ...
... homocysteine methyltransferase [EC:] K01761 E4.4.1.11; methionine-gamma-lyase [EC:] K11717 sufS; cysteine ... BBR47_36130 trmD; tRNA (guanine-N1-)-methyltransferase BBR47_20800 trmK; tRNA (adenine-N(1)-)-methyltransferase BBR47_10780 ... homocysteine methyltransferase BBR47_55420 megL; probable methionine gamma-lyase BBR47_48560 sufS; cysteine desulfurase BBR47_ ... methyltransferase [EC:] K03216 trmL; tRNA (cytidine/uridine-2-O-)-methyltransferase [EC:] K03437 spoU; RNA ...
PRMT6: Protein arginine methyltransferase 6. *PSRC1: Proline/serine-rich coiled-coil protein 1 ... doi:10.1186/gb-2010-11-5-206. PMC 2898077. PMID 20441615.. *^ "Statistics & Downloads for chromosome 1". HUGO Gene Nomenclature ... Chromosome 1 spans about 249 million nucleotide base pairs, which are the basic units of information for DNA.[5] It represents ... FRA1J encoding protein Fragile site, 5-azacytidine type, common, fra(1)(q12) ...
... homocysteine methyltransferase [EC:] K11717 sufS; cysteine desulfurase / selenocysteine lyase [EC:] ... homocysteine S-methyltransferase ABLL_0746 selenocysteine lyase/cysteine desulfurase ABLL_0004 thioredoxin reductase ABLL_2586 ... methyltransferase [EC:] K03216 trmL; tRNA (cytidine/uridine-2-O-)-methyltransferase [EC:] K00566 mnmA; tRNA- ... methyltransferase ABLL_2517 tRNA (guanine-N(1)-)-methyltransferase ABLL_1432 RNA methylase ABLL_0625 tRNA-specific 2- ...
Betaine-homocysteine S-methyltransferase GRCh38: Ensembl release 89: ENSG00000116984 - Ensembl, May 2017 GRCm38: Ensembl ... Zhu H, Wicker NJ, Shaw GM, Lammer EJ, Hendricks K, Suarez L, Canfield M, Finnell RH (March 2003). "Homocysteine remethylation ... Methionine synthase also known as MS, MeSe, MetH is responsible for the regeneration of methionine from homocysteine. In humans ... Methionine synthase catalyzes the final step in the regeneration of methionine (Met) from homocysteine (Hcy). The overall ...
... betaine-homocysteine methyltransferase (EC2.1.1.5); (7) methyleneTHF reductase (EC1.1.1.68); (8) AdoMet synthetase (EC2.5.1.6). ... 1995) Plasma homocysteine in acute myocardial infarction: homocysteine-lowering effect of folic acid. J. Intern. Med. 237:381- ... MeTHF-homocysteine methyltransferase (methionine synthase) (EC2.1.1.13); Cbl, cobalamin; CH3-Cbl, methylcobalamin; PLP, ... a key cofactor in homocysteine metabolism, which should be considered in homocysteine lowering strategies for the prevention of ...
Chronic homocysteine elevation increases s-adenosyl-L-homocysteine levels, consequently inhibiting methyltransferase activity ... Prenatal diagnosis of this condition is possible using [14C] methyltetrahydrofolate. Mutation analysis in native chorionic ... Homocysteine, a sulfur based amino acid is the main product of methionine demethylation. Elevated homocysteine is an ... A major product of methionine demethylation is homocysteine. Remethylation of homocysteine occurs via a cobalamin dependent ...
... plasma B12 and betaine-homocysteine S-methyltransferase 2 (BHMT2); and 4) homocysteine and methylenetetrahydrofolate reductase ... methyltransferase 3β (DNMT3B), methionine adenosyltransferase I α (MAT1A), MTHFD1, and MTRR (nominal P < .05; adjusted P, not ... and homocysteine) and self-reported alcohol consumption were measured at the baseline. Conditional logistic regression was ... level of erythrocyte folate and plasma homocysteine (tHcy), and genotype of 19bp del-DHFR. Dietary folate intake, erythrocyte ...
Keywords: homocysteine, methionine, folate, cobalamin, vitamin b12, TRANSFERASE. Deposited on 2003-08-20, released 2004-03-23. ... Compound: 5-methyltetrahydrofolate S-homocysteine methyltransferase. Species: Thermotoga maritima [TaxId:2336]. Database cross- ... Compound: 5-methyltetrahydrofolate S-homocysteine methyltransferase. Species: Thermotoga maritima [TaxId:2336]. Database cross- ...
5 Treanor LM, Zhou S, Janke L, Churchman ML, Ma Z, Lu T, Chen SC, Mullighan CG and Sorrentino BP: Interleukin-7 receptor ... For FACS analysis, 5×106 cells were suspended in 0.5 ml 0.5% bovine serum albumin (BSA) (Sigma-Aldrich) in PBS; fixed in PBS ... Next, the specimens were fixed for 5 min at RT in 1% formaldehyde solution; washed in PBS for 5 min at RT; dehydrated in 70% ... The FISH probe mix was centrifuged and denatured at 73°C for 5 min. Upon addition of the denaturated probe, the specimens were ...
Genetic or nutritional deficiencies in homocysteine (Hcy) metabolism lead to hyperhomocysteinemia (HHcy) and cause endothelial ... These include histone-lysine methyltransferase genes SEDT2, SEDT7, EZH2, EHMT1, EHMT2, which were up-regulated, and SUV420H2, ... Jakubowski H (2002b) Homocysteine is a protein amino acid in humans. Implications for homocysteine-linked disease. J Biol Chem ... Jakubowski H (2013) Homocysteine in protein structure/function and human disease-chemical biology of homocysteine-containing ...
... homocysteine methyltransferase 8488. 1bmtA02 - 97.4. 1081 Methylmalonyl-CoA mutase 1906. - - 49.3. 4769 Glutamate mutase sigma ...
methyltransferase like 2A. protein-coding. MTRR. 5-methyltetrahydrofolate-homocysteine methyltransferase reductase. protein- ... 0 1 2 3 4 5 6 7 8 9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z ...
Betaine-homocysteine methyltransferase (BHMT) and BHMT2 are the only enzymes that can metabolize betaine. This reaction is ... methyltetrahydrofolate, which is the active form of folate. Mutations in this gene cause the accumulation of homocysteine and a ... The adverse effects of homocysteine accumulation in the body are related to the substitution of homocysteine for methionine in ... The accumulation of homocysteine, which is caused by mutations in this pathway, has been directly linked to oxidative stress ...
... homocysteine S-methyltransferase activity, metal ion binding, methionine synthase activity, methyltransferase activity, protein ... 5. Razak AR, Siu LL, Liu FF. et al. Nasopharyngeal carcinoma: the next challenges. Eur J Cancer. 2010;46:1967-78 ... Kuang-Ming Liao1, Tung-Bo Chao2,3, Yu-Feng Tian4,5, Ching-Yih Lin6,7, Sung-Wei Lee8, Hua-Ying Chuang1, Ti-Chun Chan9, Tzu-Ju ... 5. Department of Health and Nutrition, Chia Nan University of Pharmacy & Science, Tainan, Taiwan. 6. Department of Internal ...
5-methyltetrahydrofolate-homocysteine methyltransferase Detailed info. catalyzes the cobalamin-dependent conversion of 5- ... methyltetrahydrofolate and L-homocysteine to tetrahydrofolate and L-methionine [RGD]. Gene Symbol:. UniGene #:. Refseq ...
... homocysteine methyltransferase [EC:] K01758 CTH; cystathionine gamma-lyase [EC:] K01763 SCLY; selenocysteine ... 11185 INMT; indolethylamine N-methyltransferase 9060 PAPSS2; 3-phosphoadenosine 5-phosphosulfate synthase 2 9061 PAPSS1; 3- ... methyltransferase [EC:] K13811 PAPSS; 3-phosphoadenosine 5-phosphosulfate synthase [EC:] ... 10681 GNB5; G protein subunit beta 5 54331 GNG2; G protein subunit gamma 2 2785 GNG3; G protein subunit gamma 3 2786 GNG4; G ...
  • The methylenetetrahydrofolate reductase ( MTHFR ) and 5-methyltetrahydrofolate-homocysteine methyltransferase ( MTR ) genes express key enzymes in this pathway. (
  • Two key enzymes in this pathway are methylenetetrahydrofolate reductase (MTHFR) and 5-methyltetrahydrofolate-homocysteine methyltransferase (MTR), also referred to as methionine synthase ( 5 ). (
  • Orthologous to human MTRR (5-methyltetrahydrofolate-homocysteine methyltransferase reductase). (
  • 4 5-Methyltetrahydrofolate-Homocysteine Methyltransferase Reductase (MTRR) ELISA Kits from 1 manufacturers are available on (
  • Deficiency or deregulation of the enzyme due to deficient methionine synthase reductase can directly result in elevated levels of homocysteine (hyperhomocysteinemia), which is associated with blindness, neurological symptoms, and birth defects. (
  • The observed metabolic changes suggest that S-adenosylmethionine, at least in concentrations obtained in this study, does not inhibit 5,10-methylenetetrahydrofolate reductase, the 5-methyltetrahydrofolate forming enzyme. (
  • and as an allosteric inhibitor of methyleneTHF reductase that is crucial for MeTHF synthesis and therefore for homocysteine remethylation ( Jencks and Matthews, 1987 ). (
  • Methionine synthase reductase (MTRR) is primarily involved in the reductive methylation of homocysteine to methionine, utilizing methylcob(I)alamin as an intermediate methyl carrier. (
  • 5-Methyltetrahydrofolate-Homocysteine Methyltransferase Reductase MSR [Methionine Synthase]- Cobalamin Methyltransferase (Cob(II)Alamin Reducing) Methionine Synthase Reductase, Mitochondrial EC CblE The gene was mapped to human chromosome 5. (
  • While the functional dihydrofolate reductase gene has been mapped to chromosome 5, multiple intronless processed pseudogenes or dihydrofolate reductase-like genes have been identified on separate chromosomes. (
  • Mtrr (5-methyltetrahydrofolate-homocysteine methyltransferase reductase), Fastkd3 (FAST kinase domains 3), 1700001L19Rik, Adcy2 (adenylate cyclase 2). (
  • The transgene integrated into chromosome 13 causing a 241.3 Kb deletion and disrupting the following genes: Mtrr (5-methyltetrahydrofolate-homocysteine methyltransferase reductase), Fastkd3 (FAST kinase domains 3), 1700001L19Rik, Adcy2 (adenylate cyclase 2). (
  • This research will also study whether persons having particular types of genes involved in the metabolism of methionine (5-methyltetrahydrofolate-homocysteine S-methyltransferase-MTR, MTFH reductase-MTFHR, transcobalamin 2-Tc2), and apolipoprotein E (APOE) are more likely to have delayed adverse effects after treatment for their tumors. (
  • The observation that methylenetetrahydrofolate reductase is increased in hyperthyroidism and decreased in hypothyroidism may be relevant to the relationship between plasma homocysteine levels and thyroid status. (
  • Using data from a population-based incident case-control study (1,600 cases and 1,962 controls), we investigated associations between genetic variants in the reduced folate carrier (RFC), thymidylate synthase (TS), methionine synthase (MTR), and 5,10-methylenetetrahydrofolate reductase (MTHFR) and colon cancer risk. (
  • Single nucleotide variants (SNVs) in the folate pathway affecting methylenetetrahydrofolate reductase ( MTHFR ), methionine synthase reductase ( MTRR ), 5-methyltetrahydrofolate-homocysteine S -methyltransferase (MTR), cystathionine beta-synthase ( CBS ) and methionine adenosyltransferase ( MAT1A ) were examined in 55 BWS patients with KCNQ1OT1 TSS-DMR LOM and in 100 unaffected cases. (
  • Biological processes influenced by MTRR include: sulfur amino acid metabolic process, DNA methylation, methionine metabolic process, methionine biosynthetic process, methylation, S-adenosylmethionine cycle, homocysteine catabolic process, folic acid metabolic process, oxidation-reduction process and negative regulation of cystathionine beta-synthase activity. (
  • MTHFR plays a role in the directing of one-carbon moieties from nucleic acid synthesis to methionine synthesis and methylation reactions ( 4 , 5 , 9 , 10 ). (
  • The RFC1 enzyme is responsible for absorption and intracellular transport of folate, besides transporting 5-MTHFR to the interior of variety cells, being an important determinant of folate intracellularly concentrations. (
  • The MTHFR enzyme, encoded by the MTHFR gene, is responsible for the catalysis of the irreversible reaction of 5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate , which interferes in DNA synthesis and methylation. (
  • Our Take on The MTHFR Gene ," is a 23andMe blog posting (January 5, 2017), a meta-analysis finding that the past two decades of scientific evidence as it relates to specific MTHFR-influenced health conditions to be inconclusive or conflicting, with two exceptions, 1. (
  • Considering the central role of MTHFR in folate metabolism and in control of homocysteine levels this is not surprising. (
  • This gene encodes the 5-methyltetrahydrofolate-homocysteine methyltransferase. (
  • MTR encodes the 5-methyltetrahydrofolate-homocysteine methyltransferase, which is also known as cobalamin-dependent methionine synthase, catalyzes the final step in methionine biosynthesis. (
  • The effect of oral S-adenosylmethionine on homocysteine metabolism in humans is unknown. (
  • Rather they indicate a positive effect on 5-methyltetrahydrofolate, a key cofactor in homocysteine metabolism, which should be considered in homocysteine lowering strategies for the prevention of vascular disease. (
  • These findings, in patients without a known inborn error of methionine metabolism, have established increased plasma homocysteine (hyperhomocysteinemia) as an independent risk factor for vascular events. (
  • Additionally, an interruption of the coordinate regulatory function of AdoMet in homocysteine metabolism, has recently been proposed ( Selhub and Miller, 1992 ). (
  • Further metabolism yields homocysteine that is either catabolized via transsulfuration or recycled via remethylation to methionine. (
  • The folate cycle is linked to homocysteine metabolism via MTR. (
  • Genetic or nutritional deficiencies in homocysteine (Hcy) metabolism lead to hyperhomocysteinemia (HHcy) and cause endothelial dysfunction, a hallmark of atherosclerosis. (
  • Homocysteine (Hcy) is an important intermediate in one-carbon metabolism that involves the conversion of methionine to cysteine (Mudd et al. (
  • Methionine synthase [5-methyltetrahydrofolate-homocysteine S-methyltransferase (MTR)] is involved in folate-mediated one-carbon metabolism, a pathway known to play a role in colorectal carcinogenesis. (
  • Homocysteine metabolism. (
  • An important gene associated with Methylmalonic Aciduria and Homocystinuria Type Cble is MTR (5-Methyltetrahydrofolate-Homocysteine Methyltransferase), and among its related pathways/superpathways are Cytochrome P450 - arranged by substrate type and Metabolism of water-soluble vitamins and cofactors . (
  • Epidemiological studies suggest that the imbalance of folate metabolism may be involved in predisposition to carcinogenesis, which is based on its involvement in both DNA biosynthesis and DNA methylation [ 5 ]. (
  • As an intermediate in one-carbon metabolism, 5,10-CH 2 -THF interconverts to 5-methyltetrahydrofolate , 5-formyltetrahydrofolate , and methenyltetrahydrofolate. (
  • Several human genetic rare diseases are also associated with homocysteine (Hcy) metabolism and SNHL confirming this potential link. (
  • Maternal genetic effects, exerted by genes involved in homocysteine remethylation, influence the risk of spina bifida. (
  • Furthermore, we identified a possible recruitment of ancient nonmethanogenic methyltransferase genes to establish the methanogenesis pathway. (
  • In this study, through a comprehensive phylogenetic and comparative genomic study of Mtr methyltransferase complex, we revealed an unexpected recurrent concerted evolution of mtrA genes, likely lasting throughout the whole history of the extant methanogens (over 2410 million years), after the convergent evolution of gene structure in three different archaeal lineages. (
  • First, we identified the genes that were differentially expressed in GBMs (3 datasets) compared to non-GBM brain tissues (5 datasets), or were associated with survival differences. (
  • Remethylation of homocysteine occurs via a cobalamin dependent enzyme, methionine synthase (MTR). (
  • The enzyme bound cob(I)alamin cofactor of the MTR enzyme functions as a methyl carrier between 5-MTHF and homocysteine. (
  • Catalyzing the transfer of a methyl group from methyl-cobalamin to homocysteine, yielding enzyme-bound cob(I) alamin and methionine. (
  • In enzymology, a 5-methyltetrahydropteroyltriglutamate-homocysteine S-methyltransferase (EC is an enzyme that catalyzes the chemical reaction 5-methyltetrahydropteroyltri-L-glutamate + L-homocysteine ⇌ {\displaystyle \rightleftharpoons } tetrahydropteroyltri-L-glutamate + L-methionine Thus, the two substrates of this enzyme are 5-methyltetrahydropteroyltri-L-glutamate and L-homocysteine, whereas its two products are tetrahydropteroyltri-L-glutamate and L-methionine. (
  • This enzyme belongs to the family of transferases, specifically those transferring one-carbon group methyltransferases. (
  • The systematic name of this enzyme class is 5-methyltetrahydropteroyltri-L-glutamate:L-homocysteine S-methyltransferase. (
  • Apparent Km values of the peak II enzyme for 5-methyltetrahydrofolate and homocysteine were 75 and 1.7μM, respectively. (
  • An enzyme that catalyzes the formation of methionine by transfer of a methyl group from 5-methyltetrahydrofolate to homocysteine. (
  • MTR catalyzes the methylation of homocysteine to methionine with simultaneous conversion of 5-methyletetrahydrofolate to tetrahydrofolate ( 13 ). (
  • The overall reaction transforms 5-methyltetrahydrofolate (N5-MeTHF) into tetrahydrofolate (THF) while transferring a methyl group to Homocysteine to form Methionine. (
  • Circulating blood folate (5-methyl tetrahydrofolate, 5-MTHF) donates methyl groups to MTR to be utilized in cellular methylation. (
  • Elevated plasma homocysteine concentration is an independent risk factor for vascular disease in humans. (
  • When pyridoxine supplementation was initiated at age 18 years, the patient's plasma homocysteine levels decreased below the reference range. (
  • At age 50 years, the patient's plasma homocysteine levels still remained low. (
  • In this context, different epidemiological studies have shown correlations among the nutritional condition, increased total plasma homocysteine (tHcy) and SNHL. (
  • in some species N 5-methyltetrahydrosarcinapterin is the methyl donor) ( Thauer 1998 ) to the corrinoid prosthetic group harbored by MtrA ( Hippler and Thauer 1999 ), a protein anchored to cell membrane ( Harms and Thauer 1996 ). (
  • Although no single-nucleotide polymorphism reached study-wide significance after controlling family-wise false-discovery rate at 0.05, single-nucleotide polymorphisms within the 5-methyltetrahydrofolate-homocysteine methyltransferase (MTR), Caspase 8 (CASP8), CREB-binding protein (CREBBP), lysine acetyltransferase 2B (KAT2B), and beta-transducin repeat containing (BTRC) loci were among those strongly associated with frailty. (
  • A flavoprotein amine oxidoreductase that catalyzes the reversible conversion of 5-methyltetrahydrofolate to 5,10-methylenetetrahydrofolate. (
  • It supplies a methyl group for methylation of homocysteine, producing methionine [ 14 ]. (
  • White matter damage is probably caused by reduced methyl group availability and nonphysiological fatty acids toxicity, whereas focal gliosis results from homocysteine-induced toxicity to the endothelium. (
  • The remethylation pathway comprises 2 intersecting biochemical pathways and results in the transfer of a methyl group (CH 3 ) to homocysteine from methylcobalamin, which receives its methyl group from S-adenosylmethionine (SAM), from 5-methyltetrahydrofolate (an active form of folic acid), or from betaine (trimethylglycine). (
  • Transfer of the methyl group from N5-methyltetrahydrofolates to homocysteine in Escherichia coli" (Free full text). (
  • Two of these methyl transfer reactions occur during turnover, when homocysteine is converted to methionine by using a methyl group derived from methyltetrahydrofolate. (
  • MeCbl and AdoCbl are essential coenzymes to N 5 -methyltetrahydrofolate: homocysteine methyltransferase (methionine synthase) and methylmalonyl-CoA mutase, whose functional deficiency results in methylmalonic acidemia and aciduria, hyperhomocysteinemia, homocystinuria, and hypomethioninemia. (
  • Cyclic adenosine 3',5'-monophosphate inhibits the availability of arachidonate to prostaglandin synthetase in human platelet suspensions. (
  • Methionine synthase catalyzes the final step in the regeneration of methionine (Met) from homocysteine (Hcy). (
  • Mtr, N 5 -methyltetrahydromethanopterin (CH 3 -H 4 MPT): Coenzyme M (CoM), catalyzes the second-to-last step of methanogenesis C1 pathway ( Gottschalk and Thauer 2001 ). (
  • Without functional methionine synthase, homocysteine cannot be converted to methionine. (
  • 1997. Human thiopurine methyltransferase pharmacogenetics: Gene sequence polymorphisms. (
  • The precursor homocysteine is metabolized either through the methionine cycle to produce methionine or through the transsulfuration pathway to synthesize cysteine. (
  • We propose that concurrent with decreased cystine uptake through xCT, PIK3CA mutant cells use homocysteine through the transsulfuration pathway to synthesize cysteine. (
  • These results not only provide novel evolutionary insight into the methanogenesis pathway and methyltransferase superfamily but also suggest an unanticipated long-lasting effect of gene conversion on gene evolution in a convergent pattern. (
  • Simplified picture showing homocysteine involvement in different metabolic pathways, as well as the role of vitamins B-6, B-12, and folate as a co-factors in this pathway. (
  • The transsulfuration pathway of methionine/homocysteine degradation produces the amino acids cysteine and taurine. (
  • This pathway is dependent on adequate intake of vitamin B-6 and the hepatic conversion of vitamin B-6 into its active form, pyridoxal-5'-phosphate (P5P). (
  • The amino acid serine, which is a downstream metabolite generated from betaine via the homocysteine remethylation pathway is another necessary step. (
  • 6R]-5,10-methylene-THF is a biomodulator that has proven to enhance the desired cytotoxic antitumor effect of Fluorouracil (5-FU) and can bypass the metabolic pathway required by other folates (such as leucovorin ) to achieve necessary activation. (
  • Gene specific primer pairs resulted in PCR amplification of a product matched by size to a hybrid-mapping panel containing only chromosome 5 as its human genetic material. (
  • Researchers have not determined how altered levels of homocysteine and methionine lead to the health problems associated with homocystinuria. (
  • Women tend to have lower basal levels of homocysteine than do men, and neither contraceptives nor hormone replacement therapy seems to significantly alter the levels. (
  • We investigated the effect of oral S-adenosylmethionine (400 mg) on plasma levels of 5-methyltetrahydrofolate, which is the active form of folate in the remethylation of homocysteine to methionine, S-adenosylhomocysteine, the demethylated product of S-adenosylmethionine, homocysteine and methionine over 24 hr in 14 healthy subjects. (
  • Folate and vitamin B-12 are required for the remethylation of homocysteine to methionine. (
  • Subsequently, remethylating the cofactor using methyltetrahydrofolate. (
  • This vitamer is one of two active coenzymes used by vitamin B 12 -dependent enzymes and is the specific vitamin B 12 form used by 5-methyltetrahydrofolate-homocysteine methyltransferase (MTR), also known as methionine synthase. (
  • However, despite the evidence that folic acid and other vitamins can reduce homocysteine levels, a review of 8 clinical trials concluded that the supplements provided no benefit in terms of decreasing blood clots, heart disease, cancer or overall mortality. (
  • Subsequently occurring regulatory processes can induce an aberrant stimulation of DNA methyltransferase (DNMT1) as well as changes in histone deacetylases (HDACs) and microRNAs in many cancer cell lines. (
  • Functional characterization using a hemimethylated DNA trapping assay revealed a reduced methyltransferase activity relative to wild-type DNMT1 for each variant ranging from 40 to 70% reduction in activity. (
  • 5 intronic and 1 exonic polymorphisms in the INSR gene were examined in 122 semisupercentenarians (older than 105, 107 female, 15 male, mean age 106.8 years) and 122 healthy younger controls (105 female, 17 male, mean age 33.33). (
  • abstract = "This communication reports a theoretical study of the conversion of homocysteine to methionine by methionine synthase. (
  • Homocystinuria represents a group of hereditary metabolic disorders characterized by an accumulation of homocysteine in the serum and an increased excretion of homocysteine in the urine. (
  • It is the one-carbon donor for thymidylate synthase , for methylation of 2-deoxy-uridine-5-monophosphate ( dUMP ) to 2-deoxy-thymidine-5-monophosphate ( dTMP ). (