In enzymology, a precorrin-6Y C5,15-methyltransferase (decarboxylating) (EC 2.1.1.132) is an enzyme that catalyzes the chemical reaction
2 S-adenosyl-L-methionine + precorrin-6Y ⇌ {\displaystyle \rightleftharpoons } 2 S-adenosyl-L-homocysteine + precorrin-8X + CO2
The two substrates of this enzyme are S-adenosyl methionine and precorrin 6Y; its three products are S-adenosylhomocysteine, precorrin 8X, and CO2. This enzyme belongs to the family of transferases, specifically those transferring one-carbon group methyltransferases. The systematic name of this enzyme class is S-adenosyl-L-methionine:1-precorrin-6Y C5,15-methyltransferase (C-12-decarboxylating). Other names in common use include precorrin-6 methyltransferase, precorrin-6Y methylase and CobL. This enzyme is part of the biosynthetic pathway to cobalamin (vitamin B12) in aerobic bacteria.
See also Cobalamin biosynthesis
References
Blanche F, Famechon A, Thibaut D, Debussche L, Cameron B, Crouzet J (1992). "Biosynthesis of vitamin B12 in Pseudomonas denitrificans: the biosynthetic sequence from precorrin-6y to precorrin-8x is catalyzed by the cobL gene product". J. Bacteriol. 174 (3): 1050–2. doi:10.1128/jb.174.3.1050-1052.1992. PMC 206191. PMID 1732195.


