Autoreduction phenomena of bovine heart cytochrome c oxidase and other metalloproteins.

Metalloprotein autoreduction is a complex phenomenon composed of multiple reactions, the nature of which depends on the metal, its prosthetic group, and the manner in which they interact with the protein. In all types of autoreduction the protein amino acid side chains are implicated as being a potential source of reducing equivalents, with H2O2 playing a critical role in the side chain oxidation. CO-facilitated autoreduction is distinguished from this more general process by the fact that the CO can be directly oxidized to CO2 on reacting with a peroxide-derived ferryl-oxo species. The implications of the findings with respect to methodologies for isolation of minimally perturbed hemeproteins and the mechanism of hemeprotein turnover are discussed.