Betaine—homocysteine S-methyltransferase

betaine-homocysteine S-methyltransferase
Crystal structure of rat liver betaine homocysteine s-methyltransferase.[1]
Identifiers
EC number	2.1.1.5
CAS number	9029-78-1
Databases
IntEnz	IntEnz view
BRENDA	BRENDA entry
ExPASy	NiceZyme view
KEGG	KEGG entry
MetaCyc	metabolic pathway
PRIAM	profile
PDB structures	RCSB PDB PDBe PDBsum
Gene Ontology	AmiGO / EGO
Search PMC articles PubMed articles

In the field of enzymology, a betaine-homocysteine S-methyltransferase also known as betaine-homocysteine methyltransferase is a zinc metallo-enzyme that catalyzes the transfer of a methyl group from betaine to homocysteine to produce dimethylglycine and methionine respectively:^[2]

• betaine + homocysteine → dimethylglycine + methionine

This enzyme belongs to the family of transferases, specifically those transferring one-carbon group methyltransferases. This enzyme participates in the metabolism of glycine, serine, threonine and also methionine.

Contents 1 Isozymes 2 Tissue distribution 3 Clinical significance 4 See also 5 References 6 Further reading 7 External links

Isozymes

In humans, there are two isozymes, BHMT^[3][4] and BHMT2,^[5][6] each encoded by a separate gene.

betaine-homocysteine methyltransferase Identifiers Symbol BHMT Entrez 635 HUGO 1047 OMIM 602888 RefSeq NM_001713 UniProt Q93088 Other data EC number 2.1.1.5 Locus Chr. 5 q13.1-q15

betaine-homocysteine methyltransferase 2 Identifiers Symbol BHMT2 Entrez 23743 HUGO 1048 OMIM 605932 RefSeq NM_017614 UniProt Q9H2M3 Other data EC number 2.1.1.5 Locus Chr. 5 q13

Tissue distribution

BHMT is expressed most predominantly in the liver and kidney.^[7]

Clinical significance

Anomalies in homocysteine metabolism have been implicated in disorders ranging from vascular disease to neural tube birth defects such as spina bifida.

See also

• betaine

References

Further reading

External links

• MeSH Betaine+Homocysteine+Methyltransferase
• EC 2.1.1.5

Transferase: one carbon transferases (EC 2.1) 2.1.1: Methyl- N- Histamine N-methyltransferase - Phenylethanolamine N-methyltransferase - Amine N-methyltransferase - Phosphatidylethanolamine N-methyltransferase O- 5-hydroxyindole-O-methyltransferase/Acetylserotonin O-methyltransferase - Catechol-O-methyl transferase Homocysteine Betaine-homocysteine methyltransferase - Homocysteine methyltransferase - Methionine synthase Other Phosphatidyl ethanolamine methyltransferase - DNMT3B - Histone methyltransferase - Thymidylate synthase - DNA methyltransferase - Thiopurine methyltransferase 2.1.2: Hydroxymethyl-, Formyl- and Related Hydroxymethyltransferase Serine hydroxymethyltransferase - 3-methyl-2-oxobutanoate hydroxymethyltransferase Formyltransferase Phosphoribosylglycinamide formyltransferase - Inosine monophosphate synthase Other Glutamate formimidoyltransferase - Aminomethyltransferase 2.1.3: Carboxy- and Carbamoyl Carboxy methylmalonyl-CoA carboxytransferase Carbamoyl Aspartate carbamoyltransferase - Ornithine carbamoyltransferase - Oxamate carbamoyltransferase - Putrescine carbamoyltransferase - 3-hydroxymethylcephem carbamoyltransferase - Lysine carbamoyltransferase - N-acetylornithine carbamoyltransferase 2.1.4: Amidino Arginine:glycine amidinotransferase B enzm: 1.1/2/3/4/5/6/7/8/10/11/13/14/15-18, 2.1/2/3/4/5/6/7/8, 2.7.10, 2.7.11-12, 3.1/2/3/4/5/6/7, 3.1.3.48, 3.4.21/22/23/24, 4.1/2/3/4/5/6, 5.1/2/3/4/99, 6.1-3/4/5-6

Metabolism: amino acid metabolism · synthesis and catabolism enzymes (essential in CAPS) K→acetyl-CoA LYSINE→ Saccharopine dehydrogenase · Glutaryl-CoA dehydrogenase LEUCINE→ Branched chain aminotransferase · Branched-chain alpha-keto acid dehydrogenase complex · Isovaleryl coenzyme A dehydrogenase · Methylcrotonyl-CoA carboxylase · Methylglutaconyl-CoA hydratase · 3-hydroxy-3-methylglutaryl-CoA lyase TRYPTOPHAN→ Indoleamine 2,3-dioxygenase/Tryptophan 2,3-dioxygenase · Arylformamidase · Kynureninase · 3-hydroxyanthranilate oxidase · Aminocarboxymuconate-semialdehyde decarboxylase · Aminomuconate-semialdehyde dehydrogenase PHENYLALANINE→tyrosine→ (see below) G G→pyruvate →citrate glycine→serine→ Serine hydroxymethyltransferase · Serine dehydratase glycine→creatine: Guanidinoacetate N-methyltransferase · Creatine kinase alanine→ Alanine transaminase cysteine→ D-cysteine desulfhydrase threonine→ L-threonine dehydrogenase G→glutamate→ α-ketoglutarate HISTIDINE→ Histidine ammonia-lyase · Urocanate hydratase · Formiminotransferase cyclodeaminase proline→ Proline oxidase · Pyrroline-5-carboxylate reductase · 1-Pyrroline-5-carboxylate dehydrogenase/ALDH4A1 · PYCR1 arginine→ Ornithine aminotransferase · Ornithine decarboxylase · Agmatinase →alpha-ketoglutarate→TCA Glutamate dehydrogenase Other cysteine+glutamate→glutathione: Gamma-glutamylcysteine synthetase · Glutathione synthetase · Gamma-glutamyl transpeptidase glutamate→glutamine: Glutamine synthetase · Glutaminase G→propionyl-CoA→ succinyl-CoA VALINE→ Branched chain aminotransferase · Branched-chain alpha-keto acid dehydrogenase complex · Enoyl-CoA hydratase · 3-hydroxyisobutyryl-CoA hydrolase · 3-hydroxyisobutyrate dehydrogenase · Methylmalonate semialdehyde dehydrogenase ISOLEUCINE→ Branched chain aminotransferase · Branched-chain alpha-keto acid dehydrogenase complex · 3-hydroxy-2-methylbutyryl-CoA dehydrogenase METHIONINE→ generation of homocysteine: Methionine adenosyltransferase · Adenosylhomocysteinase regeneration of methionine: Methionine synthase/Homocysteine methyltransferase · Betaine-homocysteine methyltransferase conversion to cysteine: Cystathionine beta synthase · Cystathionine gamma-lyase THREONINE→ Threonine aldolase →succinyl-CoA→TCA Propionyl-CoA carboxylase · Methylmalonyl CoA epimerase · Methylmalonyl-CoA mutase G→fumarate PHENYLALANINE→tyrosine→ Phenylalanine hydroxylase · Tyrosine aminotransferase · 4-Hydroxyphenylpyruvate dioxygenase · Homogentisate 1,2-dioxygenase · Fumarylacetoacetate hydrolase tyrosine→melanin: Tyrosinase G→oxaloacetate asparagine→aspartate→ Asparaginase/Asparagine synthetase · Aspartate transaminase M: MET mt, k, c/g/r/p/y/i, f/h/s/l/o/e, a/u, n, m k, cgrp/y/i, f/h/s/l/o/e, au, n, m, epon m(A16/C10),i(k, c/g/r/p/y/i, f/h/s/o/e, a/u, n, m)