Peroxidative damage to cardiac mitochondria: Identification and purification of modified adenine nucleotide translocase

Abstract Rat myocardial membranes exposed to free radical-generating systems exhibit both lipid peroxidation and protein alterations. The most sensitive protein, a 28-kDa polypeptide, was previously shown to increase slightly in apparent molecular weight before disappearing completely from the protein profile [ N. L. Parinandi, C. W. Zwizinski, and H. H. O. Schmid (1991) Arch. Biochem. Biophys. 289, 118–123]. We now report that isolated cardiac mitochondria contain a 28-kDa protein which responds in the same manner to treatment with Cu 2+ / t -butylhydroperoxide. The protein exhibits several characteristic properties of the mitochondrial adenine nucleotide translocase. This assignment is supported by the finding that carboxyatractyloside, a specific inhibitor of the adenine nucleotide translocase, can prevent the oxidant-induced changes in the 28-kDa protein. Efficient purification schemes for the isolation of milligram quantities of unmodified and oxidatively altered adenine nucleotide translocase from rat heart mitochondria are described.