1. Interaction of azide with beef heart mitochondrial ATPase
- Author
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Stephen G. Daggett, Thaddeus A. Tomaszek, and Sheldon M. Schuster
- Subjects
Azides ,Biophysics ,chemistry.chemical_element ,Mitochondrion ,Binding, Competitive ,Biochemistry ,Catalysis ,Mitochondria, Heart ,chemistry.chemical_compound ,Hydrolysis ,Animals ,Magnesium ,Binding site ,Anion binding ,Molecular Biology ,chemistry.chemical_classification ,Binding Sites ,Chemistry ,Kinetics ,Proton-Translocating ATPases ,Enzyme ,Models, Chemical ,Cattle ,Azide ,Mathematics - Abstract
This study examined the inhibition of azide as a probe of the magnesium regulation of beef heart mitochondrial ATPase (F 1 ) catalysis. Azide elicited a slow hysteretic effect on both ATP and ITP hydrolysis of F 1 . This hysteretic effect was shown to be due to the consecutive binding of magnesium and azide, and to be independent of catalytic turnover. The azide binding site was also shown to be separate from the anion binding HCO 3 − site on F 1 . The results presented indicate that metal binding is important in the inhibition of the hydrolytic activity and regulation of F 1 . A model is presented which is consistent with the hysteretic inhibition of F 1 by azide, in which there is a slow equilibration between free enzyme and the enzyme-magnesium-azide complex.
- Published
- 1985
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