Tightly bound adenosine diphosphate, which inhibits the activity of mitochondrial F1-ATPase, is located at the catalytic site of the enzyme.
The binding of one ADP molecule at the catalytic site of the nucleotide depleted F1-ATPase results in a decrease in the initial rate of ATP hydrolysis. The addition of an equimolar amount of ATP to the nucleotide depleted F1-ATPase leads to the same effect, but, in this case, inhibition is time dependent. The half-time of this process is about 30 s, and the inhibition is correlated with Pi dissociation from the F1-ATPase catalytic site (uni-site catalysis). The F1-ATPase-ADP complex formed under uni-site catalysis conditions can be reactivated in two ways: (i) slow ATP-dependent ADP release from the catalytic site (tau 1/2 20 s) or (ii) binding of Pi in addition to MgADP and the formation of the triple F1-ATPase-MgADP-Pi complex. GTP and GDP are also capable of binding to the catalytic site, however, without changes in the kinetic properties of the F1-ATPase. It is proposed that ATP-dependent dissociation of the F1-ATPase-GDP complex occurs more rapidly, than that of the F1-ATPase-ADP complex.
Drobinskaya
I Y
IY
Kozlov
I A
IA
Murataliev
M B
MB
Vulfson
E N
EN
D000244:Adenosine Diphosphate / Q000378:metabolism* / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D001665:Binding Sites; D006153:Guanosine Diphosphate / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism / Q000494:pharmacology; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D008928:Mitochondria / Q000201:enzymology*; D010710:Phosphates / Q000378:metabolism; D006180:Proton-Translocating ATPases / Q000037:antagonists & inhibitors* / Q000378:metabolism
D010710:Phosphates; D006153:Guanosine Diphosphate; D000244:Adenosine Diphosphate; D006160:Guanosine Triphosphate; D000255:Adenosine Triphosphate; D006180:Proton-Translocating ATPases; D008274:Magnesium