Evidence for a new intermediate state in the mechanism of (Na+ + K+)-adenosine triphosphatase.
A rapid mixing technique was used to follow the intermediate formation of phosphorylated enzyme and liberation of inorganic phosphate by a microsomal preparation of (Na+ + K+)-ATPase. In the presence of 100 mM Na+,but without added K+, phosphorylation reaches a constant level at a rate which is dependent on ATP concentration. Inorganic phosphate production lags during the inital phase of phosphorylation and then accumulates at a constant rate. These observations favor a scheme in which Pi is liberated as the result of turnover of the phosphorylated enzyme. In the presence of 100 mM Na+ and 2.5 mM K+ phosphate production was resolved into two phases consisting of an initial 'burst' and late steady state phase...
D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D004557:Electric Organ / Q000201:enzymology; D004789:Enzyme Activation / Q000187:drug effects; D005399:Fishes; D007700:Kinetics; D008861:Microsomes / Q000187:drug effects / Q000201:enzymology; D011188:Potassium / Q000494:pharmacology*; D012964:Sodium / Q000494:pharmacology*
D000255:Adenosine Triphosphate; D012964:Sodium; D000251:Adenosine Triphosphatases; D011188:Potassium