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Biological proton pumping in an oscillating electric field.

Authors
  • Kim, Young C
  • Furchtgott, Leon A
  • Hummer, Gerhard
Type
Published Article
Journal
Physical Review Letters
Publisher
American Physical Society
Publication Date
Dec 31, 2009
Volume
103
Issue
26
Pages
268102–268102
Identifiers
PMID: 20366348
Source
Medline
License
Unknown

Abstract

Time-dependent external perturbations provide powerful probes of the function of molecular machines. Here we study biological proton pumping in an oscillating electric field. The protein cytochrome c oxidase is the main energy transducer in aerobic life, converting chemical energy into an electric potential by pumping protons across a membrane. With the help of master-equation descriptions that recover the key thermodynamic and kinetic properties of this biological "fuel cell," we show that the proton pumping efficiency and the electronic currents in steady state depend significantly on the frequency and amplitude of the applied field, allowing us to distinguish between different microscopic mechanisms of the machine. A spectral analysis reveals dominant reaction steps consistent with an electron-gated pumping mechanism.

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