ISOLATION AND COMPARATIVE-STUDIES OF MITOCHONDRIAL F1-ATPASE FROM RATTESTIS AND BEEF-HEART

The isolation and properties of F-1-mitochondrial ATPase from rat test is are described. The isolation medium involves a chloroform extractio n, and it is suitable even with small amounts of starting material tha t have a relatively low specific activity as in the case of rat testis submitochondrial particles. The isolated enzyme from rat testis had a specific activity of 30-45 mu mol Pi/min/mg protein, which could be i ncreased up to 90 mu mol Pi/min/mg protein only in the presence of bic arbonate and maleate. The isolated enzyme represented less than 0.6% o f the initial membrane proteins. It exhibited a typical five-band patt ern in sodium dodecyl sulfate gel electrophoresis. However, it showed a ratio of subunits alpha:beta higher than the heart enzyme; its signi ficance is unknown. The purified enzyme was cold labile and inhibited by natural ATPase inhibitor protein from bovine heart mitochondria and by dicyclohexylcarbodiimide. The results presented suggest that the l ow ATPase activity of testis submitochondrial particles is due to a re duced content of the F-1-ATPase. (C) 1997 Elsevier Science Inc.