Green Hemoprotein of Erythrocytes: Methemoglobin Superoxide Transferase
SCHOOL OF AEROSPACE MEDICINE BROOKS AFB TX
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Influences of base pH10, heat 50C, microwave radiation 2450 MHz, 103 or - 4 Wkg, and hydrogen peroxide 5.6 mM generated by glucose oxidase on oxidation of human oxyhemoglobin to methemoglobin were examined. Conversion of oxyhemoglobin to methemoglobin was followed by the difference in absorbancy of 540 or 542 nm and 576 nm wavelength light versus time. Fresh basic hemolysates auto-oxidized on heating with a zero order rate constant, implying that hemoglobin or another protein saturated with oxyhemoglobin catalyzed the oxidation. Simultaneous microwave irradiation inhibited thermally induced auto- oxidation on the average by 28.6. However, there was great variability among samples and a decrease in auto-oxidation with aging of individual samples. The auto-oxidation rate was independent of initial oxyhemoglobin concentration. Oxidation of partially purified oxyhemoglobin by hydrogen peroxide was not influenced by microwave irradiation. Adding green hemoprotein isolated from human erythrocytes to the oxyhemoglobinglucose oxidase reaction mixture yielded absorption spectra 500-600 nm that were a combination of oxyhemoglobin, deoxyhemoglobin, and methemoglobin spectra. Reprints.