title: Heme degradation during autoxidation of oxyhemoglobin.
abstract: Two fluorescent heme degradation compounds are detected during autoxidation of oxyhemoglobin. These fluorescent compounds are similar to fluorescent compounds formed when hydrogen peroxide reacts with hemoglobin [E. Nagababu and J. M. Rifkind, Biochem. Biophys. Res. Commun. 247, 592-596 (1998)]. Low levels of heme degradation in the presence of superoxide and catalase are attributed to a reaction involving the superoxide produced during autoxidation. The inhibition of most of the degradation by catalase suggests that the hydrogen peroxide generated during autoxidation of oxyhemoglobin produces heme degradation by the same mechanism as the direct addition of hydrogen peroxide to hemoglobin. The formation of the fluorescent degradation products was inhibited by the peroxidase substrate, ABTS, which reduces ferrylhemoglobin to methemoglobin, indicating that ferrylhemoglobin is produced during the autoxidation of hemoglobin. It is the transient formation of this highly reactive Fe(IV) hemoglobin, which is responsible for most of the heme degradation during autoxidation.
authors.affiliation: National Institute on Aging, Laboratory of Cellular, Molecular Biology, National Institutes of Health, 5600 Nathan Shock Drive, Baltimore, Maryland 21224-6825, USA.
authors.forename: E
authors.initials: E
authors.lastname: Nagababu
authors.forename: J M
authors.initials: JM
authors.lastname: Rifkind
mesh_terms: D006418:Heme / Q000378:metabolism*; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D006868:Hydrolysis; D010084:Oxidation-Reduction; D010108:Oxyhemoglobins / Q000378:metabolism*; D013050:Spectrometry, Fluorescence
chemical_list: D010108:Oxyhemoglobins; D006418:Heme; D006861:Hydrogen Peroxide