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J Biol Chem 2007 Feb 16;282(7):4894-907

Structural basis of peroxide mediated changes in human hemoglobin: A novel oxidative pathway.

Jia Y, Buehler PW, Boykins RA, Venable RM, Alayash AI

Abstract

Hydrogen peroxide (H2O2) triggers a redox cycle between ferric and ferryl-hemoglobin (Hb) leading to the formation of a transient protein radical and a covalent heme-protein crosslink. Addition of H2O2 to highly purified human hemoglobin (HbA0) induced structural changes that primarily resided within ss subunits followed by the internalization of the heme moiety within a subunits. These modifications were observed when equal molar concentration of H2O2 was added to HbA0 yet became more abundant with greater concentration of H2O2. Mass spectrometric and amino acid analysis revealed for the first time that ssCys93 and ssCys112 were oxidized extensively and irreversibly to cysteic acid, when HbA0 was treated with H2O2. Oxidation of further amino acids in HbA0 exclusive to the globin chain included modification of ssTrp15 to oxyindolyl and kynureninyl products as well as ssMet55 to methionine sulfoxide. These findings may explain therefore the premature collapse of the ss subunits as a result of the H2O2 attack. Analysis of a tryptic digest of the main reversed phase-HPLC fraction revealed two a peptide fragments (a128- a139) and a heme moiety with the loss of iron, cross-linked between aSer138 and the porphyrin ring. The novel oxidative pathway of HbA0 modification detailed here may explain the diverse oxidative, toxic and potentially immunogenic effects associated with the release of hemoglobin from red blood cells during hemolytic diseases and/or when cell-free Hb is used as a blood substitute.


Category: Journal Article
PubMed ID: #17178725
Includes FDA Authors from Scientific Area(s): Biologics
Entry Created: 2011-10-04 Entry Last Modified: 2012-08-29
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