Precorrin-2 C20-methyltransferase

In enzymology, a precorrin-2 C20-methyltransferase is an enzyme that catalyzes the chemical reaction


 * S-adenosyl-L-methionine + precorrin-2 $$\rightleftharpoons$$ S-adenosyl-L-homocysteine + precorrin-3A

The two substrates of this enzyme are S-adenosyl methionine and precorrin 2 and its two products are S-adenosylhomocysteine and precorrin 3A.

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:precorrin-4 C20-methyltransferase and another names in common use is CobI. The enzyme is part of the biosynthetic pathway to cobalamin (vitamin B12) in aerobic bacteria.

Structural studies
As of late 2007, two structures have been solved for this class of enzymes, with PDB accession codes and.