Protein self-modification by heme-generated reactive species.

Summary In the presence of H2O2, heme proteins form active intermediates, which are able to oxidize exogenous molecules. Often these products are not stable compounds but reactive species on their own, such as organic radicals. They can both diffuse to the bulk of the solution or react with the protein that generated them. Here, we describe the self-modification underwent by heme proteins with globin-type fold, that is, myoglobin, hemoglobin, and neuroglobin when treated with NO2 2 or catechols in the presence of H2O2. The reactive nitrogen species generated by NO2 2 give rise to nitration, oxidation, and/or crosslinking reactions between the proteins or their subunits. The quinones formed upon reaction with catechols easily modify Cys and His residues and eventually cause protein aggregation, which induces precipitation. The pattern of modifications undergone by the protein strongly depends on the nature of the protein and the reaction conditions. 2007 IUBMB IUBMB Life, 60(1): 41–56, 2008