Protamine inhibition of the oxidative phosphorylation in intact, cytochrome c-depleted and restored mitochondria

Acta Biol Med Ger. 1975;34(4):539-47.

Abstract

On the basis of polarographic data it is shown that protamine has a biphasic effect on the respiration of intact mitochondria. At lower protamine concentrations respiration is stimulated and this combined with a decrease of the respiratory control index; at higher ones respiration is inhibited and respiratory control is lost. In cytochrome c-depleted and restored mitochondria protamine effect on oxidative phosphorylation is only inhibitory. Increasing cytochrome c concentrations restore respiration in protamine-treated cytochrome c depleted mitochondria but not the respiratory control. Binding of cytochrome c to mitochondria is studied by determining from Scatchard plots the number of high affinity binding sites (n) and their stability constants (K). In absence of protamine in intact mitochondria n = 2.7 and K = 4.67-10(6) M-1; in cotochrome c depleted mitochondria n = 4.7 and K = 5.16-10(6) M-1. In both types of mitochondria protamine decreases significantly n as well as K. These data show that protamine may affect oxidative phosphorylation by causing desorption of cytochrome c from the inner mitochondrial membrane.

MeSH terms

  • Adenosine Diphosphate / metabolism
  • Binding Sites
  • Cytochrome c Group / deficiency
  • Mitochondria / metabolism*
  • Mitochondria, Liver / metabolism
  • Oxidative Phosphorylation / drug effects*
  • Oxygen Consumption
  • Protamines / pharmacology*

Substances

  • Cytochrome c Group
  • Protamines
  • Adenosine Diphosphate