An Electron Transport Particle from Yeast: Purification and Properties

Previously, Crane, Glenn, and Green (1) have described the purification and properties of an electron transport particle (ETP)’ from beef heart. The ETP was similar in composition and properties to the reduced diphosphopyridine nucleotide oxidase described earlier by Mackler and Green (2, 3) and, in addition, carried out the oxidation of succinate by molecular oxygen. The ETP preparation contained copper, nonheme iron, lipid, coenzyme Q, flavin, and cytochromes b, cl, c, and a.% Succinate and DPNH oxidase activities were inhibited by antimycin A, but only the DPNH oxidase was inhibited by Amytal. Other electron transport particles, isolated from hotobacter v&elan&i (4) and from cauliflower buds (5), differ from the beef heart ETP in their cytochrome composition. The ETP from A. vinelandii contained copper, nonheme iron, flavin, and lipid in amounts similar to the beef heart system but was antimycin-insensitive and did not catalyze the reduction of mammalian cytochrome c. The present paper describes the purification and properties of an ETP prepared from Saccharomyces cerevisiae. Differences in composition, structure, and kinetic properties between this enzyme system and the previously reported preparations of ETP from other sources (1, 4, 5) will be discussed.