- An oxygen atom from dioxygen is incorporated into the macrocycle at
C-20.
- In the aerobic cobalamin biosynthesis pathway, four enzymes are
involved in the conversion of precorrin-3A to precorrin-6A.
- This enzyme carries out the first of the four steps, yielding
precorrin-3B as the product.
- This is followed by three methylation reactions, which introduce a
methyl group at C-17 (CobJ; EC 2.1.1.131), C-11 (CobM; 2.1.1.133) and
C-1 (CobF; EC 2.1.1.152) of the macrocycle, giving rise to precorrin-
4, precorrin-5 and precorrin-6A, respectively.
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