Tyrosine residues as redox cofactors in human hemoglobin: implications for engineering nontoxic blood substitutes.

ABSTRACT: Respiratory proteins such as myoglobin and hemoglobin can, under oxidative conditions, form ferryl heme iron and protein-based free radicals. Ferryl myoglobin can safely be returned to the ferric oxidation state by electron donation from exogenous reductants via a mechanism that involves two distinct pathways. In addition to direct transfer between the electron donor and ferryl heme edge, there is a second pathway that involves "through-protein" electron transfer via a tyrosine residue (tyrosine 103, sperm whale myoglobin). Here we show that the heterogeneous subunits of human hemoglobin, the alpha and beta chains, display significantly different kinetics for ferryl reduction by exogenous reductants. By using selected hemoglobin mutants, we show that the alpha chain possesses two electron

SUBMITTER: Reeder BJ 

PROVIDER: S-EPMC2662160 | biostudies-literature | 2008 Nov

REPOSITORIES: biostudies-literature