The mechanism of disulphide reduction by mitochondria.

1. Cystamine was reduced to the corresponding thiol by rat liver mitochondria, even in the presence of rotenone or antimycin A. 2.

A permeability barrier in mitochondria in ;high-energy states' against positively charged disulphides.

1. In rat liver mitochondria in state 1 or 4 there is a permeability barrier against cystamine, probably in the inner membrane. 2.

Effects of cystamine and cysteamine on the peroxidation of lipids and the release of proteins from mitochondria.

1. Cystamine slightly stimulated the peroxidation of lipids in mitochondria. Maximal effects were obtained at low concentrations (0.

Effects of cystamine and cysteamine on the adenosine-triphosphatase activity and oxidative phosphorylation of rat-liver mitochondria.

1. Cystamine (2,2'-diaminodiethyl disulphide) caused an unmasking of mitochondrial adenosine triphosphatase and a leakage of Mg(2+) from the mitochondria, and decreased the stimulation of adenosine triphosphatase by 2,4-dinitrophenol. When Mg(2+) was added, cystamine potentiated the activation of adenosine triphosphatase by 2,4-dinitrophenol.

THE EFFECT OF DISULPHIDES ON MITOCHONDRIAL OXIDATIONS.

1. Nicotinamide nucleotide-linked mitochondrial oxidations were inhibited by the disulphides NNN'N'-tetraethylcystamine, cystamine and cystine diethyl ester, whereas l-homocystine, oxidized mercaptoethanol, oxidized glutathione, NN'-diacetylcystamine and tetrathionate were only slightly inhibitory. Mitochondrial oxidations were not blocked by the thiol cysteamine.