Intracellular mechanisms for the decomposition of a lipid peroxide. II. Decomposition of a lipid peroxide by subcellular fractions

The properties of subcellular fractions of rat liver in catalyzing the decomposition of linoleic acid hydroperoxide have been compared with those of transition salts, heme compounds, and nucleophiles. The properties compared included the range of products produced, the pH dependence of the reaction, and the effects of metal-complexing agents, inhibitors, and hydrogen donors. It was concluded that the decomposition of the hydroperoxide in the liver cell was due principally to reaction with the intracellular nucleophile glutathione by a mechanism catalyzed by the enzyme glutathione peroxidase. In the absence of glutathione, however, both the mitochondrial and microsomal fractions decomposed the hydroperoxide presumably by a radical mechanism probably involving the cytochromes.