Zinc irreversibly damages major enzymes of energy production and antioxidant defense prior to mitochondrial permeability transition.

Recent observations point to the role played by Zn2+ as an inducer of neuronal death. Two Zn2+ targets have been identified that result in inhibition of mitochondrial respiration: the bc1 center and, more recently, alpha-ketoglutarate dehydrogenase. Zn2+ is also a mediator of oxidative stress, leading to mitochondrial failure, release of apoptotic peptides, and neuronal death.

On the localized coupling of respiration and phosphorylation in mitochondria.

This paper is an overview of the theoretical and experimental studies performed in our laboratory to answer the question whether there exist conditions where the hypothetical mechanism of the localized coupling of respiration and phosphorylation postulated by R. Williams in 1961 operates. These studies were undertaken to verify the earlier suggestion that mitochondria may exist in two structural and functional states.

Detection of the local H+ gradients on the internal mitochondrial membrane.

Respiration-dependent responses of a pH probe (fluorescein isothiocyanate, FITC), covalently bound to the membrane proteins of mitochondria and submitochondrial particles (SMP) have been studied. A spectral shift indicating FITC deprotonation was observed when respiration was activated in coupled mitochondria. Such a response was increased by valinomycin and reduced by uncoupler.

The immobilized matrix buffer controls the rate of mitochondrial respiration in state 3P according to chance.

Preparations of coupled mitochondria were labeled with fluorescein isothiocyanate (FITC). Comparison of characteristics of FITC bound to mitochondria versus azolectin liposomes indicates that a significant part of the probe is bound to mitochondrial proteins including proteins of the matrix side of the inner membrane. The experiments with the probe indicate that mitochondrial proteins resemble typical polyelectrolytes with constant of dissociation close to 10(-7).

On the mechanism of oligomycin inhibition of Ca(2+)-induced mitochondrial respiration.

The addition of oligomycin in the presence of Ca2+ increased the ADP pool in mitochondrial suspension. It is suggested that oligomycin inhibition of Ca(2+)-induced mitochondrial respiratory activation is the function of the increased endogenous ADP pool. Low ADP concentrations (5-20 microM) produce the same inhibitory effect as oligomycin.