1.14.13.83	precorrin-3A + NADH + H+ + O2 = precorrin-3B + NAD+ + H2O	An iron-sulfur protein. 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), C-11 (CobM) and C-1 (CobF	-	
1.14.13.83	precorrin-3A + NADH + H+ + O2 = precorrin-3B + NAD+ + H2O	reaction mechanism of CobZ	671939