The requirement for serum albumin in oxidative phosphorylation of flight muscle mitochondria.

Houseflies, Musca domestica, of both sexes from 4 to 7 days old were used. These were reared and maintained by the procedure described earlier (3). Flight muscle mitochondria, or sarcosomes, were isolated by the technique already reported (4, 5). Oxygen consumption measurements were made in a conventional Warburg apparatus. The temperature was 25” and the gas phase was air. Inorganic phosphate was assayed by the method of Fiske and SubbaRow (6). ADP and hexokinase (practical, type III) were purchased from the Sigma Chemical Company. BSA,’ crystallized, was obtained from Pentex Inc. and Armour Laboratories. Human serum albumin was prepared by Cutter Laboratories. Bovine y-globulin and /3-lactoglobulin were obtained from Pentex Inc. Bovine hemoglobin (purified) and blood Fraction IV-l, prepared by Cohn’s method (7), were supplied by Armour Laboratories. Ovalbumin (crystalline) and edestin were obtained from Mann Research Laboratories, Inc. and the Worthington Biochemical Corporation, respectively.