Hemoglobin can nitrate itself and other proteins

Incubation of human hemoglobin with nitrite and hydrogen peroxide was found to induce autonitration and nitration of another protein (bovine serum alb umin), as demonstrated by detection of nitrotyrosine residues in Western bl ots of separated membrane proteins. Inhibition of nitration by conversion o f hemoglobin into the cyanmet form demonstrates that nitration is due to th e pseudoperoxidase activity of hemoglobin. Incubation of whole erythrocytes with nitrite and hydrogen peroxide induces nitration of erythrocyte membra ne proteins, much stronger when cellular catalase was inhibited with azide. These results suggest that hemoglobin and other hemoproteins may contribut e to the tyrosine nitration in vivo. (C) 2001 Published by Elsevier Science B.V.