Membranous Effects on Adenosine Triphosphatase Activities of Mitochondria from Rat Liver and Morris Hepatoma 3924A1

and hepatoma mitochondrial ATPases were comparable below the break (34.5 and 35.5 kcal/mole, respectively) and above the break (11.6 and 9.2 kcal/mole, respectively). Solubilization of the mitochondrial membranes with Triton X-100 resulted in constant and similar values of energy of activation for the ATPases. Kmvalues of hepatoma and rat liver mitochondrial ATPases for adenosine triphosphate were similar in both the membrane-bound and solubilized states. The lack of uncoupler-stimulated ATPase activity in hepatoma mitochondria is apparently not due to membra nous effects on the affinity of the ATPase for adenosine triphosphate.