Purification of the head-pieces of the elementary particles from beef heart mitochondria: their morphological structure and enzymatic activity

1. In order to obtain direct evidence for the enzymatic identification of the head-pieces of the elementary particles in the inner mitochondrial membrane, the head-pieces were detached by sonication from the isolated inner membrane of beef heart mitochondria, purified by pursuing the particles with the electron microscope, and analyzed for enzymatic properties. 2. Electron microscope examination revealed that the isolated headpieces are the spherical particles about 90À in diameter which are quite similar in appearance to the head-pieces of the elementary particles lining the inner mitochondrial membranes. 3. The head-pieces are identified as ATPase sensitive to oligomysin when attached by stalks to the membrane, and become insensitive when detached or purified from the membrane. 4. The head-piece is labile to cold with respect to ATPase activity and morphology.