Inhibition by avidin of the ATP-Pi enchange activities associated with preparations of energy transfer factors A and A-D

Two water-soluble protein fractions were isolated from sonic extracts of beef heart mitochondria, which corresponded to the energy transfer factors A and A·D (ATP synthetase) described by Sanadi and coworkers. Both fractions augmented the activities of “urea” particles for ATP-Pi exchange and ATP-dependent DPN reduction by succinate. These activities were strongly inhibited by rutamycin. In the absence of added particles, both soluble fractions exhibited ATP-Pi exchange activities, which were not affected by rutamycin, but were strongly inhibited by avidin. The inhibitory effect of avidin was abolished when it was pretreated with biotin. The soluble fractions also exhibited avidin-sensitive propionyl-coenzyme A carboxylase activities, which were compatible with their ATP-Pi exchange activities.