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Coupling mechanisms in ATP-driven pumps

R M Krupka1

  • 1London Research Centre, Agriculture Canada, Canada.

Biochimica Et Biophysica Acta
|November 2, 1993
PubMed
Summary

Active transport mechanisms, both primary and secondary, share fundamental kinetic principles. Carrier protein design and function are similar, relying on substrate binding to induce conformational changes for transport control.

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Area of Science:

  • Biochemistry
  • Molecular Biology
  • Membrane Transport

Background:

  • Primary and secondary active transport kinetic schemes can be identical.
  • Fundamental relationships exist between rate and equilibrium constants in transport processes.

Purpose of the Study:

  • To elucidate the shared structural and kinetic principles governing primary and secondary active transport.
  • To explain how carrier proteins achieve controlled substrate mobility and specificity.

Main Methods:

  • Analysis of kinetic reaction schemes and equilibrium constants.
  • Examination of substrate binding and dissociation constants.
  • Postulation of protein conformational changes driven by substrate interactions.

Main Results:

  • The ratio of coupled to uncoupled flux is limited by substrate dissociation constants.
  • Substrate order of addition influences its role in transport coupling.
  • Carrier protein structure and function are fundamentally alike in both transport types.

Conclusions:

  • Substrate binding forces alter protein conformation, controlling carrier mobility and specificity.
  • Non-covalent interactions between substrate and protein drive conformational changes.
  • The proposed model explains cation occlusion and inorganic phosphate reactions in pumps.

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