Abstract
The effect of H2O2 on the primary structure of OxyHb was studied. Upon treatment of Oxy Hb with H2O2 ([Heme]/[H2O2] =I), tryptophan and methionine residues of the /-chain were modified. Treatment of ApoHb with H2O2 resulted in the modification of histidine and methionine residues in both globin chains. Tryptophan residues were unaffected. Modification of methionine residues in both the β-chain of OxyHb and ApoHb probably results from the direct oxidation of mcthionine by H2O2. The modification of histidine residues in ApoHb may be mediated by a metal-catalyzed oxidation system comprised of H2O2 and histidine-bound iron. The H2O2-mediated modification of tryptophan in the OxyHb β-chain. however, requires the heme moiety.