title: ATP binding and hydrolysis steps of the uni-site catalysis by the mitochondrial F(1)-ATPase are affected by inorganic phosphate.
abstract: The effect of inorganic phosphate (P(i)) on uni-site ATP binding and hydrolysis by the nucleotide-depleted F(1)-ATPase from beef heart mitochondria (ndMF(1)) has been investigated. It is shown for the first time that P(i) decreases the apparent rate constant of uni-site ATP binding by ndMF(1) 3-fold with the K(d) of 0.38+/-0.14mM. During uni-site ATP hydrolysis, P(i) also shifts equilibrium between bound ATP and ADP+P(i) in the direction of ATP synthesis with the K(d) of 0.17+/-0.03mM. However, 10mM P(i) does not significantly affect ATP binding during multi-site catalysis.
authors.affiliation: Department of Biochemistry and Molecular Biology, State University of New York, Upstate Medical University, Syracuse, NY 13210, USA. milgromy@upstate.edu
authors.forename: Yakov M
authors.initials: YM
authors.lastname: Milgrom
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D000465:Algorithms; D000818:Animals; D001665:Binding Sites; D055162:Biocatalysis / Q000187:drug effects; D002417:Cattle; D006868:Hydrolysis / Q000187:drug effects; D007700:Kinetics; D008929:Mitochondria, Heart / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D025261:Mitochondrial Proton-Translocating ATPases / Q000378:metabolism*; D010710:Phosphates / Q000494:pharmacology*; D011485:Protein Binding / Q000187:drug effects; D013379:Substrate Specificity
chemical_list: D010710:Phosphates; D000255:Adenosine Triphosphate; D025261:Mitochondrial Proton-Translocating ATPases