precorrin-2 + S-adenosyl-L-methionine = precorrin-3A + S-adenosyl-L-homocysteine + H(+)
precorrin-2 + s-adenosyl-l-methionine = precorrin-3a + s-adenosyl-l-homocysteine + h(+)
"precorrin-2 C(20)-methyltransferase"
"precorrin-2 c(20)-methyltransferase"