The interaction of H+ and K+ with the partial reactions of gastric (H+ + K+)-ATPase.

摘要: The influence of H+ and K+ on the partial reactions transport gastric (H+ + K+)-ATPase was studied. Using transient kinetics, effects sidedness formation breakdown phosphoenzyme were determined in intact lyophilized reconstituted vesicles absence presence gramicidin. Whereas increasing concentrations ATP-binding face accelerates phosphorylation, inhibits phosphorylation. Increasing this side reduces inhibition phosphorylation rate. At low ATP/K+ ratios, step can become rate-limiting for steady state hydrolysis. Decreasing dephosphorylation K+. internal or luminal dephosphorylation, rate is reduced with concentrations. pH, K+-dependent may rate-limiting. measurements using fluorescence quenching acridine orange show that whereas required transport, external a pH gradient, by decreasing medium pH. optimum ATPase activity correlated vesicles, K0.5 data parietal cells.