Involvement of phosphate-modified ATP analogs in the reactions of oxidative phosphorylation

Abstract

Various analogs of adenosine 5′-triphosphate with a modified terminal phosphate group have been tested in energy-requiring reactions with intact mitochondria and submitochondrial particles. It is shown that the fluorophosphate analog ATP(γF) is a strong inhibitor of mitochondrial respiration and of energy requiring reactions which involve the participation of high energy intermediates, generated aerobically by the respiratory chain. On the other hand, ATP(γF) does not affect the ATPase activity of intact or disrupted mitochondria and is less effective in inhibiting ATP-driven reactions. The imidophosphate analog AMP- P(NH) P also inhibits the partial reactions of oxidative phosphorylation, but does not affect ATP synthesis from ADP and P i. In contrast to ATP(γF), it is a strong inhibitor of both soluble and membrane-bound mitochondrial ATPases. The biological implication of the complementary effects of ATP(γF) and AMP- P(NH) P on mitochondria-catalysed reactions is discussed while suggesting the use of such nucleotide analogs as specific tools for the study of ATP-forming and ATP-utilizing reactions in mitochondria.