PMID: 8972704Dec 4, 1996Paper

Kinetics of conformational changes associated with potassium binding to and release from Na+/K(+)-ATPase

Biochimica Et Biophysica Acta
P R PratapJ D Robinson

Abstract

The Na+/K(+)-ATPase functions in cells to couple energy from the hydrolysis of ATP to the transport Na+ out and K+ in. The fluorescent probe IAF (iodoacetamidofluorescein) covalently binds to this enzyme, reporting conformational changes without inhibiting enzyme activity. This paper describes experiments using dog kidney enzyme labeled with IAF to examine kinetics of conformational changes resulting from added Na+ and K+, measured in terms of steady-state and stopped-flow fluorescence changes. Kinetics of these fluorescence changes were examined as a function of temperature from two initial conditions: (a) enzyme in the high-fluorescence form (E(high)) was rapidly mixed with varying [K+]; and (b) enzyme in the low-fluorescence form (E(low)) was rapidly mixed with varying [ATP]. These experiments showed: (1) The rate constant for the fluorescence change from E(high) to E(low) was much larger than that for the opposite transition, E(low) to E(high); (2) the apparent free energy of activation (Ea(app)) for the two transitions were different (as estimated from Arrhenius plots); (3) under steady-state conditions, IAF fluorescence did not change when ATP was added to E(low)(K+) in the absence of Na+; (4) the apparent free energy of ...Continue Reading

References

Aug 17, 1979·Biochimica Et Biophysica Acta·J D Robinson, M S Flashner
Apr 1, 1991·The Journal of Membrane Biology·W StürmerP Läuger
Nov 4, 1991·Biochimica Et Biophysica Acta·J D Robinson, P R Pratap
Nov 2, 1987·Biochimica Et Biophysica Acta·M ShaniS J Karlish
Feb 1, 1974·Proceedings of the Society for Experimental Biology and Medicine·D C Johnson, E B Brown
Jul 28, 1983·Biochimica Et Biophysica Acta·J C Skou, M Esmann
Aug 1, 1994·The Journal of General Physiology·S HeyseW Stürmer

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Citations

Feb 20, 2009·European Biophysics Journal : EBJ·Ronald James Clarke
Sep 6, 2012·Biophysical Journal·Alvaro GarciaRonald J Clarke
Sep 22, 2001·Biophysical Journal·C LüpfertR J Clarke
May 15, 2013·The Journal of Clinical Endocrinology and Metabolism·Laurent MaïmounCharles Sultan
Jul 24, 2002·Biochemistry·Paul A HumphreyRonald J Clarke
Feb 26, 2004·Biochemistry·Benjamin Y Kong, Ronald J Clarke

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