[Properties of epsilon-ATP hydrolysis by CF1-ATPase from pea chloroplasts].
The ATPase activity of CF1 isolated from pea chloroplasts with epsilon-ATP, the fluorescent analog of ATP and ATP used as substrates, in the presence of Mg2+, Ca2+ and sodium sulfite (stimulator of the ATPase activity) was studied. The rate of epsilon-ATP hydrolysis in the presence of Mg2+ is nearly two times as low as that of ATP; an addition of sodium sulfite to the reaction mixture increases the reaction rate without changing the above ratio. The rate of Ca2+-dependent hydrolysis of epsilon-ATP is rather low as compared to that in the presence of Mg2+. epsilon-ADP is a competitive inhibitor of Mg2+-dependent ATPase reaction and inhibits this process in the presence of Ca2+, the inhibition being of a mixed type. Modification of CF1 by covalent binding of epsilon-ADP results in a 70-80% decrease of the Mg2+-dependent ATPase activity, the Ca2+-dependent ATPase activity is changed only insignificantly thereby. The differences in the activation of ATP and epsilon-ATP hydrolyses by Ca2+ and Mg2+ can be accounted for by the existence of two sites in the active center of CF1, which are specific for Mg2+ and Ca2+, respectively. It is concluded that the binding of epsilon-ADP occurs in the Mg2+-dependent ATPase site of the active center.
D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives*; D002118:Calcium / Q000494:pharmacology; D002736:Chloroplasts / Q000201:enzymology*; D004985:Ethenoadenosine Triphosphate / Q000378:metabolism*; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D010944:Plants / Q000201:enzymology; D006180:Proton-Translocating ATPases
D004985:Ethenoadenosine Triphosphate; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; D006180:Proton-Translocating ATPases; D008274:Magnesium; D002118:Calcium
Osobennosti gidroliza epsilon-ATP CF1-ATPazoĭ khloroplastov gorokha.