On the mechanism of H+ translocation by mitochondrial H+-ATPase. Studies with chemical modifier of tyrosine residues |
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Authors: | F Guerrieri A Yagi T Yagi S Papa |
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Institution: | (1) Institute of Biological Chemistry, Faculty of Medicine, Center for the Study of Mitochondria and Energy Metabolism, University of Bari, Italy;(2) Department of Biochemistry, Scripps Clinic and Research Foundation, La Jolla, California |
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Abstract: | In this paper a detailed study of the effect of nitration of tyrosine residues by tetranitromethane on H+ conduction and other reactions catalyzed by the H+-ATPase complex in phosphorylating submitochondrial particles, uncoupled particles, and the purified complex is presented. Tetranitromethane treatment of submitochondrial particles results in marked inhibition of ATP hydrolysis, ATP-33Pi exchange, and proton conduction by the H+-ATPase complex. These effects are caused by nitration of tyrosine residues of H+-ATPase complex as shown by the appearance of the absorption peak at 360 nm (specific for nitrotyrosine formation) and inhibition of ATP hydrolysis and ATP-33Pi exchange in the complex purified from tetranitromethane-treated particles. H+ conduction in phospholipid vesicles inlaid with F0 is also inhibited by tetranitromethane treatment. These observations indicate that tyrosine residue(s) of F0 are critically involved in energy-linked proton translocation in the ATP-ase complex. |
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Keywords: | H+-ATPase proton conduction amino acid modification |
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