Phosphorylated intermediate of the ATPase from the plasma membrane of yeast.

摘要: A purified preparation of the plasma-membrane ATPase from Saccharomyces cerevisiae was phosphorylated when incubated with (γ-32P]ATP. The phosphoprotein formed has characteristics an enzyme intermediate because its rapidity phosphorylation and dephosphorylation. When analyzed by polyacrylamide gel electrophoresis in sodium dodecylsulfate only one band a molecular weight 100000 contained radioactivity. This represented about 80% protein enrichment course purification correlated increase specific activity. Both reaction exhibited apparent dissociation constant for enzyme-ATP complex 0.2 mM, further implicating phosphoenzyme as reaction. sensitivity bond to alkaline pH hydroxylamine indicate that it is acylphosphate. From maximum level (0.7 nmol/mg) activity at 30° C (21 μmol × min−1× mg−1) turnover number 30000 min−1 can be calculated. not affected either inhibitors vanadate dicyclohexylcarbodiimide or ADP. These results yeast subunit composition mechanism similar cation-pumping ATPases animal plasma membranes.