[Energy-dependent inhibition of mitochondrial NAD.H-oxidase and succinic oxidase by strong nitrous bases]

Abstract

The inhibitory effect of organic cations from the group of hydrazones on phosphorylated respiration in mitochondria with a succinate as a substrate has been shown to be completely reversed by 2,4-dinitrophenol (DNP). The effect observed has not been due to the action directly on the ATP-synthetase because the inhibition of ATPase, NADH-succinate oxidase and ascorbate oxidase activities occurs at a wide concentration range of compounds studied. The concentration of organic cations used for the inhibition of the respiration in submitochondria particles (SMP) as compared with respiration in mitochondria is higher; in case of SMP the inhibitory effect is not reversed by DNP. These results allow to conclude that the high inhibitory effect of organic cations is due to the energy-dependent binding of these compounds to the enzyme in the membrane phase of mitochondria.