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ENZYME

ENZYME entry: EC 2.1.1.13

PURL: https://purl.expasy.org/enzyme/EC/2.1.1.13
Accepted Name
methionine synthase
Alternative Name(s)
5-methyltetrahydrofolate--homocysteine S-methyltransferase
5-methyltetrahydrofolate--homocysteine transmethylase
B12 N(5)-methyltetrahydrofolate homocysteine methyltransferase
cobalamin-dependent methionine synthase
methionine synthase (cobalamin-dependent)
methionine synthetase
methyltetrahydrofolate--homocysteine vitamin B12 methyltransferase
N(5)-methyltetrahydrofolate--homocysteine cobalamin methyltransferase
N(5)-methyltetrahydrofolate methyltransferase
N(5)-methyltetrahydrofolic--homocysteine vitamin B12 transmethylase
N-methyltetrahydrofolate:L-homocysteine methyltransferase
tetrahydrofolate methyltransferase
tetrahydropteroylglutamate methyltransferase
tetrahydropteroylglutamic methyltransferase
vitamin B12 methyltransferase
Reaction catalysed
(6S)-5-methyl-5,6,7,8-tetrahydrofolate + L-homocysteine = (6S)-5,6,7,8-tetrahydrofolate + L-methionine
Comment(s)
  • The enzyme becomes inactivated occasionally during its cycle by oxidation of Co(I) to Co(II).
  • Reactivation by reductive methylation is catalyzed by the enzyme itself, with S-adenosyl-L-methionine as the methyl donor and a reducing system.
  • For the mammalian enzyme, the reducing system involves NADPH and EC 1.16.1.8.
  • In bacteria, the reducing agent is flavodoxin, and no further catalyst is needed (the flavodoxin is kept in the reduced state by NADPH and EC 1.18.1.2).
  • Acts on the monoglutamate as well as the triglutamate folate, in contrast with EC 2.1.1.14, which acts only on the triglutamate.
Cross-references
BRENDA2.1.1.13
EC2PDB2.1.1.13
ExplorEnz2.1.1.13
KEGG Ligand Database for Enzyme Nomenclature2.1.1.13
IUBMB Enzyme Nomenclature2.1.1.13
MEDLINEFind literature relating to 2.1.1.13
MetaCyc2.1.1.13
Rhea expert-curated reactions2.1.1.13
UniProtKB/Swiss-Prot
Q5E814, METH_ALIF1Q9AJQ8, METH_ALIFSQ4JIJ3, METH_BOVIN
A8XY95, METH_CAEBRQ09582, METH_CAEELQ54P92, METH_DICDI
P13009, METH_ECOLIQ99707, METH_HUMANA6H5Y3, METH_MOUSE
Q49775, METH_MYCLEO33259, METH_MYCTUQ9I2Q2, METH_PSEAE
O33465, METH_PSEPUQ9Z2Q4, METH_RATP37586, METH_SALTY
Q55786, METH_SYNY3Q9KUW9, METH_VIBCHQ87L95, METH_VIBPA
Q8DCJ7, METH_VIBVUQ7MHB1, METH_VIBVY

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