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Control of ATP hydrolysis in chloroplasts
Author(s) -
Strotmann Heinrich,
Kleefeld Sigrid,
Lohse Detlev
Publication year - 1987
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(87)80938-9
Subject(s) - atp hydrolysis , hydrolysis , atpase , chemistry , electrochemical gradient , chemiosmosis , atp synthase , chloroplast , biophysics , phosphate , adenosine diphosphate , adenosine triphosphate , substrate (aquarium) , enzyme , biochemistry , membrane , biology , gene , ecology , platelet , platelet aggregation , immunology
Dark ATP hydrolysis catalysed by the membrane‐bound preactivated thiol‐modified chloroplast ATPase was measured at constant initial ATP concentration and constant initial phosphate potential c ATP / c ADP ·c P i which was adjusted by inverse variation of the concentrations of ADP and P i . Under these conditions, the rate of ATP hydrolysis is strongly inhibited as the concentration of ADP is increased and the concentration of P i is decreased. Inhibition is preferentially caused by ADP‐dependent inactivation of ATPase molecules. At low initial ADP concentration, the transmembrane proton gradient generated by effective ATP hydrolysis protects the enzyme from deactivation in spite of progressive accumulation of ADP because energy‐dependent release of ADP counteracts its binding. Deactivation due to incorporation of ADP occurs, however, when the proton gradient decreases as a consequence of exhaustion of substrate ATP.