The adducts of cyano- and aquacobalamin with hypochlorite

Abstract

Hypochlorite is known to oxidatively degrade the corrin ring of cobalamin. Here, transient reaction intermediates are described in the reaction of aqua as well as of cyano-cobalamin with hypochlorite, using stopped-flow UV-vis kinetics. For aqua-cobalamin, the intermediate is assigned as arising from substitution of the aqua ligand with hypochlorite. For cyano-cobalamin, the intermediate is proposed to arise from substitution of the benzimidazole ligand trans to the cyanide. In both cases, the intermediates would feature a new Co(III)-OCl^-bond-which is also supported by density functional theory (DFT) calculations.

Keywords: Cobalt; DFT; Hypochlorous acid; Stopped-flow; UV–vis; Vitamin B12.