Study of cobalamin adducts with cysteine and its oxidized sulfenic, sulfinic and sulfonic derivatives

Abstract

In this paper, the reactivity of cobalamin towards S-oxidized cysteine derivatives (sulfenic, sulfinic, sulfonic and S-sulfate) is analyzed and compared to the reactivity towards related nitrogen, oxygen and sulfur-based ligands, focusing on the concept of linkage isomerism. UV-Vis spectra complemented by DFT and TD-DFT calculations show that cysteine and its oxidized derivatives do yield adducts, with a preference for binding to the cobalt through the sulfur.