Mechanistic considerations of the vanadium haloperoxidases

Haloperoxidases are enzymes which catalyze the oxidation of halide ions (i.e. chloride, bromide and iodide) by hydrogen peroxide. These enzymes usually contain the FeHeme moiety or vanadium as an essential constituent at their active site, however, a few haloperoxidases which lack a metal cofactor are known. This review will examine (1) the reactivity of the vanadium haloperoxidases, particularly the mechanism of halide oxidation by hydrogen peroxide, and the mechanism of halogenation and sulfoxidation, including the newly reported regioselectivity and enantioselectivity of the vanadium haloperoxidases; (2) the X-ray structure of vanadium chloroperoxidase, the vanadium(V) active site and the role of critical amino acid side chains for catalysis and (3) functional biomimetic systems, with specific relevance to the mechanism of the vanadium haloperoxidase enzymes.