ATP binding and hydrolysis steps of the uni-site catalysis by the mitochondrial F1-ATPase are affected by inorganic phosphate |
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| Authors: | Yakov M Milgrom |
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| Institution: | Department of Biochemistry and Molecular Biology, State University of New York, Upstate Medical University, Syracuse, NY 13210, USA |
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| Abstract: | The effect of inorganic phosphate (Pi) on uni-site ATP binding and hydrolysis by the nucleotide-depleted F1-ATPase from beef heart mitochondria (ndMF1) has been investigated. It is shown for the first time that Pi decreases the apparent rate constant of uni-site ATP binding by ndMF1 3-fold with the Kd of 0.38 ± 0.14 mM. During uni-site ATP hydrolysis, Pi also shifts equilibrium between bound ATP and ADP + Pi in the direction of ATP synthesis with the Kd of 0.17 ± 0.03 mM. However, 10 mM Pi does not significantly affect ATP binding during multi-site catalysis. |
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| Keywords: | F1 the solubilized portion of FoF1-ATP synthase MF1 EcF1 and TF1 F1-ATPases from mitochondria Escherichia coli and thermophilic Bacillus PS3 respectively ndMF1 nucleotide-depleted MF1 |
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