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 (0.5mm). 2. Cysteamine, when allowed to autoxidize, had much stronger effects than cystamine. 3. Cysteamine and GSH did not induce peroxidation when their autoxidation was counteracted. 4. When kept reduced, cysteamine prevented the ascorbate-induced peroxidation of lipids. GSH was less efficient. 5. Cystamine as well as cysteamine prevented the loss of proteins from mitochondria induced by ascorbate, whereas cadaverine, GSSG and GSH were inefficient.