title: Further investigations on the inorganic phosphate binding site of beef heart mitochondrial F1-ATPase.
abstract: The possibility that 4-azido-2-nitrophenyl phosphate (ANPP), a photoreactive derivative of inorganic phosphate (Pi) [Lauquin, G., Pougeois, R., & Vignais, P. V. (1980) Biochemistry 19, 4620-4626], could mimic ATP was investigated. ANPP was hydrolyzed in the dark by sarcoplasmic reticulum Ca2+-ATPase in the presence of Ca2+ but not in the presence of ethylene glycol bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid. ANPP was not hydrolyzed by purified mitochondrial F1-ATPase; however, ADP and ATP protected F1-ATPase against ANPP photoinactivation. On the other hand, the trinitrophenyl nucleotide analogues (TNP-ADP, TNP-ATP, and TNP-AMP-PNP), which bind specifically at the two catalytic sites of F1-ATPase [Grubmeyer, C., & Penefsky, H. (1981) J. Biol. Chem. 256, 3718-3727], abolished Pi binding on F1-ATPase; they do not protect F1-ATPase against ANPP photoinactivation. Furthermore, ANPP-photoinactivated F1-ATPase binds the TNP analogues in the same way as the native enzyme. The Pi binding site of F1-ATPase, which is shown to be photolabeled by ANPP, does not appear to be at the gamma-phosphate position of the catalytic sites.
authors.forename: R
authors.initials: R
authors.lastname: Pougeois
authors.forename: G J
authors.initials: GJ
authors.lastname: Lauquin
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000266:Adenylyl Imidodiphosphate / Q000494:pharmacology; D000818:Animals; D001665:Binding Sites; D002417:Cattle; D007700:Kinetics; D008929:Mitochondria, Heart / Q000201:enzymology*; D010710:Phosphates / Q000378:metabolism*; D010761:Phosphorus Radioisotopes; D010777:Photochemistry; D011485:Protein Binding; D006180:Proton-Translocating ATPases / Q000378:metabolism*
chemical_list: D010710:Phosphates; D010761:Phosphorus Radioisotopes; D000266:Adenylyl Imidodiphosphate; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D006180:Proton-Translocating ATPases