Evidence for a new intermediate state in the mechanism of (Na+ + K+)-adenosine triphosphatase

• Published in: The Journal of biological chemistry Vol. 251; no. 7; pp. 2186 - 2188
• Main Authors: Froehlich, J P, Albers, R W, Koval, G J, Goebel, R, Berman, M
• Format: Journal Article
• Language: English
• Published: United States American Society for Biochemistry and Molecular Biology 10-04-1976
• Subjects: Adenosine Triphosphatases - metabolism; Adenosine Triphosphate - pharmacology; Animals; Electric Organ - enzymology; Enzyme Activation - drug effects; Fishes; Kinetics; Microsomes - drug effects; Microsomes - enzymology; Potassium - pharmacology; Sodium - pharmacology
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(17)33676-1

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...