ACTIVATION OF PLANT PLASMA-MEMBRANE H-ATPASE BY THE NONIONIC DETERGENT BRIJ-58()

Plasma membrane vesicles were purified from tobacco callii and the mod ulation of H+-ATPase by detergents was investigated. The nonionic dete rgent Brij 58 not only activated ATP hydrolysis (2-fold) but also prot on pumping (more than 4-fold). Triton X-100, within a more limited con centration range, produced a similar effect. The simultaneous activati on of ATP hydrolysis and proton pumping is not compatible with current interpretations of effects of nonionic detergents on the H+-ATPase ba sed on latency of the enzyme and opening of vesicles.