Adenosine triphosphatase activity of heart mitochondria of the turtle, Chrysemys picta

Abstract

1. 1. ATPase activity has been estimated in heart mitochondria of the fresh-water turtle, Chrysemys picta. 2. 2. This activity is Mg 2+-dependent and stimulated by the presence of DNP. 3. 3. The pH optima of ATPase activities are 8·5 with Mg 2+ ions, and 7·4 in the presence of DNP. 4. 4. Differential responses to inhibitors are evident in the presence of added Mg 2+ ions or DNP, with DNP-stimulated activities being sensitive to a wider spectrum of inhibitors and to the aging process. 5. 5. Bovine serum albumin, but not EDTA, effectively preserves DNP-stimulated ATPase activity during aging. A causal relationship with fatty acids is implied. 6. 6. These data may be used to support either a one or a two enzyme hypothesis, with the latter being favored.