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Steady state kinetic studies of purified yeast plasma membrane proton-translocating ATPase.

Publication ,  Journal Article
Koland, JG; Hammes, GG
Published in: J Biol Chem
May 5, 1986

The plasma membrane H+-ATPase from bakers' yeast was purified and reconstituted with phosphatidylserine. The steady state kinetics of ATP hydrolysis catalyzed by the H+-ATPase were studied over a wide range of Mg2+ and ATP concentrations. Whereas MgATP was the substrate hydrolyzed, excess concentrations of either Mg2+ or ATP were inhibitory. The dependence of the steady state initial velocity of ATP hydrolysis on the concentration of MgATP at a fixed concentration of Mg2+ was sigmoidal rather than hyperbolic. This precluded mechanisms involving only activation and inhibition by Mg2+ and competitive inhibition by ATP. Two alternative interpretations of these results are: 1) the enzyme possesses multiple catalytic sites which interact cooperatively; or 2) the enzyme can exist in multiple conformational states which catalyze MgATP hydrolysis by parallel pathways. The rate laws for both mechanisms are identical so that the two mechanisms cannot be distinguished on the basis of the kinetic data. The data are well fit by the rate law for these mechanisms with the inclusion of competitive inhibition by Mg2+ and ATP and an independent inhibition site for Mg2+.

Duke Scholars

Published In

J Biol Chem

ISSN

0021-9258

Publication Date

May 5, 1986

Volume

261

Issue

13

Start / End Page

5936 / 5942

Location

United States

Related Subject Headings

  • Saccharomyces cerevisiae
  • Proton-Translocating ATPases
  • Models, Biological
  • Mathematics
  • Magnesium
  • Kinetics
  • Cell Membrane
  • Biochemistry & Molecular Biology
  • Adenosine Triphosphate
  • 11 Medical and Health Sciences
 

Citation

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Koland, J. G., & Hammes, G. G. (1986). Steady state kinetic studies of purified yeast plasma membrane proton-translocating ATPase. J Biol Chem, 261(13), 5936–5942.
Koland, J. G., and G. G. Hammes. “Steady state kinetic studies of purified yeast plasma membrane proton-translocating ATPase.J Biol Chem 261, no. 13 (May 5, 1986): 5936–42.
Koland JG, Hammes GG. Steady state kinetic studies of purified yeast plasma membrane proton-translocating ATPase. J Biol Chem. 1986 May 5;261(13):5936–42.
Koland, J. G., and G. G. Hammes. “Steady state kinetic studies of purified yeast plasma membrane proton-translocating ATPase.J Biol Chem, vol. 261, no. 13, May 1986, pp. 5936–42.
Koland JG, Hammes GG. Steady state kinetic studies of purified yeast plasma membrane proton-translocating ATPase. J Biol Chem. 1986 May 5;261(13):5936–5942.

Published In

J Biol Chem

ISSN

0021-9258

Publication Date

May 5, 1986

Volume

261

Issue

13

Start / End Page

5936 / 5942

Location

United States

Related Subject Headings

  • Saccharomyces cerevisiae
  • Proton-Translocating ATPases
  • Models, Biological
  • Mathematics
  • Magnesium
  • Kinetics
  • Cell Membrane
  • Biochemistry & Molecular Biology
  • Adenosine Triphosphate
  • 11 Medical and Health Sciences