Mechanism Of Autoxidation Of Hemoglobin Kempsey Beta-99 Asp-asn
January 1, 1984 - TOMODA, A; TAKIZAWA, T; YONEYAMA, Y
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EmailJournal or Book Title: HEMOGLOBIN
Volume/Issue: 8
Year Published: 1984
The mechanism of autoxidation of [human] HbO2 Kempsey (.beta.99 Asp .fwdarw. Asn) was studied at pH 7.0, 37.degree. C, using isoelectric focusing electrophoresis. During autoxidation, 2 intermediate Hb, (.alpha.2+.beta.3+)2 and (.alpha.3+.beta.2+)2 were observed, and these were consecutively changed to methemoglobin. The autoxidation rates of HbO2 Kempsey were reduced about 43% by the addition of catalase and superoxide dismutase, but were not significantly changed by the addition of inositol hexaphosphate. This abnormal Hb autooxidized more slowly than normal Hb A. The differences in the autoxidation rates between these Hb were explained by the changes in quaternary structure of these proteins. The reaction rate constant, k+1, k+2, k+3 and k+4 of each step including the reactions: (.alpha.2+.beta.3+)2 .**GRAPHIC**. (.alpha.2+.beta.3+)2 .**GRAPHIC**. (.alpha.3+.beta.3+)2 and (.alpha.2+.beta.2+)2 .**GRAPHIC**. (.alpha.k3+.beta.2+)2 .**GRAPHIC**. (.alpha.3+.beta.3+)2 were determined by the analysis of fractional changes in these Hb derivatives during the autoxidation. The difference in the reaction rate constants between k+1 and k+3 was explained by the nonequivalence of a .alpha. and .beta. chans in tetrameric HbO2 Kempsey. The reaction mechanism of autoxidation of Hb Kempsey was discussed on the basis of these kinetic results.
DOI: 10.3109/03630268408991707
Type of Publication: Article
