Toxicity of pentachlorophenol on isolated plant mitochondria

Abstract

Pentachlorophenol (PCP) is a powerful uncoupler of the oxidative phosphorylations on isolated potato or Mung bean mitochondria; a 50%. uncoupling is obtained at less than 1 μM in a medium devoid of Bovine serum albumin (BSA). Furthermore, at higher concentrations PCP inhibits the electron transfer at the level of Complex II and also at a level located near the quinone pool. The high uncoupling activity is dependent on the presence of five chlorines on the phenyl ring, which increase the lipophily of the phenol and decrease its p K a . The 2,6-dichloro substitution is favorable to the Complex II inhibition. The presence of BSA 0.1% in the reaction medium causes the disappearance of the uncoupling effect of 3 μM PCP and the restoration of the normal increase in the oxidation rate which depends on AD. Comparison of the uncoupling effect of PCP in plant and rat liver mitochondria suggests that some proteic components of the animal mitochondria play the same role as exogenous BSA in the case of plant mitochondria.