This enzyme, which participates in the aerobic (late cobalt insertion) cobalamin biosynthesis pathway, generates hydrogenobyrinate a,c-diamide, the substrate required by EC
6.6.1.2, cobaltochelatase, which adds cobalt to the macrocycle. The equivalent reaction in the anaerobic cobalamin biosynthesis pathway is catalysed by EC
6.3.5.11, cobyrinate a,c-diamide synthase.