Studies on the ATPase complex from beef-heart mitochondria. I. Isolation and characterization of an oligomycin-sensitive and an olgiomycin-insensitive ATPase complex from beef-heart mitochondria

Abstract

1. A new method for the isolation of the oliogomycin-sensitive ATPase from beef-heart mitochondria is described. 2. A Triton-soluble ATPase complex was isolated as a by-product of the standard procedure, or as the main product when the submitochondrial particles were pretreated with 1% Triton. The ATPase activity of this complex is sensitive neither to oligomycin nor to dicyclohexylcarbodiimide. 3. The ATPase activity of the oligomycin-sensitive ATPase complex is nearly completely dependent on added phospholipids. The highest activation was found with asolectin. 4. The oligomycin-sensitive complex can be integrated into phospholipid vesicles resulting in an ATP- and Mg2+-dependent energization of the vesicles as monitored with the fluorescent dye 9-amino-6-chloro-2-methoxyacridine. 5. Aurovertin-binding studies based on fluorescence measurement reveal the presence of 1.5 mumol aurovertin-binding sites per g protein for the oligomycin-sensitive complex and about 2.2 mumol for the oligomycin-insensitive complex. 6. The preparation of the oligomycin-sensitive complex contains at least 6--7 polypeptides in addition to those derived from F1. One of these polypeptides, with an apparent molecular weight of 31 000, is virtually absent from the oligomycin-insensitive complex. 7. Some of these polypeptides have been identified and isolated.