Betaine—homocysteine S-methyltransferase

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betaine-homocysteine S-methyltransferase
BHMT ribbon view.png
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

In the field of enzymology, a betaine-homocysteine S-methyltransferase also known as betaine-homocysteine methyltransferase (BHMT) 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.

Isozymes[edit]

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
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
Locus Chr. 5 q13

Tissue distribution[edit]

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

Clinical significance[edit]

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

See also[edit]

References[edit]

  1. ^ PDB 1UMY; González B, Pajares MA, Martínez-Ripoll M, Blundell TL, Sanz-Aparicio J (May 2004). "Crystal structure of rat liver betaine homocysteine s-methyltransferase reveals new oligomerization features and conformational changes upon substrate binding". J. Mol. Biol. 338 (4): 771–82. doi:10.1016/j.jmb.2004.03.005. PMID 15099744. 
  2. ^ Pajares MA, Pérez-Sala D (December 2006). "Betaine homocysteine S-methyltransferase: just a regulator of homocysteine metabolism?". Cell. Mol. Life Sci. 63 (23): 2792–803. doi:10.1007/s00018-006-6249-6. PMID 17086380. 
  3. ^ Garrow TA (September 1996). "Purification, kinetic properties, and cDNA cloning of mammalian betaine-homocysteine methyltransferase". J. Biol. Chem. 271 (37): 22831–8. PMID 8798461. 
  4. ^ Sunden SL, Renduchintala MS, Park EI, Miklasz SD, Garrow TA (September 1997). "Betaine-homocysteine methyltransferase expression in porcine and human tissues and chromosomal localization of the human gene". Arch. Biochem. Biophys. 345 (1): 171–4. doi:10.1006/abbi.1997.0246. PMID 9281325. 
  5. ^ Chadwick LH, McCandless SE, Silverman GL, Schwartz S, Westaway D, Nadeau JH (November 2000). "Betaine-homocysteine methyltransferase-2: cDNA cloning, gene sequence, physical mapping, and expression of the human and mouse genes". Genomics 70 (1): 66–73. doi:10.1006/geno.2000.6319. PMID 11087663. 
  6. ^ Szegedi SS, Castro CC, Koutmos M, Garrow TA (April 2008). "Betaine-homocysteine S-methyltransferase-2 is an S-methylmethionine-homocysteine methyltransferase". J. Biol. Chem. 283 (14): 8939–45. doi:10.1074/jbc.M710449200. PMC 2276374. PMID 18230605. 
  7. ^ Sunden SL, Renduchintala MS, Park EI, Miklasz SD, Garrow TA (September 1997). "Betaine-homocysteine methyltransferase expression in porcine and human tissues and chromosomal localization of the human gene". Arch. Biochem. Biophys. 345 (1): 171–4. doi:10.1006/abbi.1997.0246. PMID 9281325. 

Further reading[edit]

  • Klee WA, Richards HH, Cantoni GL (1961). "The synthesis of methionine by enzymic transmethylation. VII Existence of two separate homocysteine methylpherases on mammalian liver". Biochim. Biophys. Acta. 54: 157–64. doi:10.1016/0006-3002(61)90948-9. PMID 14456704. 

External links[edit]