The effects of ADP on reverse electron flow and the oxygen exchange reactions catalyzed by bovine heart muscle submitochondrial particles.
1,N6-Ethenoadenosine diphosphate (epsilon-ADP) inhibits reverse electron flow (succinate leads to NAD+ driven by ATP) by competing with ATP, in contrast to ADP which we have shown previously to be a noncompetitive inhibitor. From these and other data it is concluded that the noncompetitive inhibition noted with ADP results from a combination of competitive inhibition plus non- or uncompetitive inhibition, the former occurring at a relatively nonspecific catalytic site and the latter at an extracatalytic site apparently quite specific for ADP. ADP, which stimulates ATP in equilibrium H2O and Pi in equilibrium H2O exchanges appears to be necessary for inhibition by arsenate of these exchanges. It is suggested that the ATP-supported Pi in equilibrium H2O exchange may be predominantly of the medium or intermediate type, depending on the concentrations of the Mg2+ complexes of ADP and Pi. Thus only exchanges involving medium ADP and Pi would be expected to show arsenate sensitivity.
D000244:Adenosine Diphosphate / Q000031:analogs & derivatives / Q000494:pharmacology*; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D001149:Arsenates / Q000494:pharmacology; D001667:Binding, Competitive; D002417:Cattle; D003864:Depression, Chemical; D004579:Electron Transport / Q000187:drug effects; D008931:Mitochondria, Muscle / Q000378:metabolism* / Q000648:ultrastructure; D010101:Oxygen Consumption / Q000187:drug effects*; D010710:Phosphates / Q000378:metabolism
D001149:Arsenates; D010710:Phosphates; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate