The effects of detergents on the ATPase activity of plasma membrane prepared by phase partitioning from sunflower roots.

MgATPase activity of plasma membrane from sunflower roots purified by phase partitioning was tested using different permeabilizing agents. MgATPase activity showed similar dependence on Triton X-100, digitonin and Zwittergent 3-14 concentration, the curves resulted from the stimulatory and inhibitory reactions. The latency calculated at their optima was only 52%. In case of n-octyl glucoside the latency was 77%, while the highest latency (82%) was measured in the presence of lysophosphatidylcholine, and it was the only surfactant which did not inhibit the PM ATPase even at 10 times the concentration giving maximum release of latent activity. Therefore, for the further characterization of the PM ATPase lysophosphatidylcholine is suggested to be used as detergent.