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Updated: Jul 17, 2026
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Single Liposome Measurements for the Study of Proton-Pumping Membrane Enzymes Using Electrochemistry and Fluorescent Microscopy
Published on: February 21, 2019
Kinetic models of redox-coupled proton pumping
Young C Kim1, Mårten Wikström, Gerhard Hummer
1Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0520, USA.
Summary
Cytochrome c oxidase uses electrostatic forces and nonlinear gates to pump protons, mimicking biological machines and inspiring new fuel cells.
Area of Science:
- Biochemistry
- Bioenergetics
- Molecular Biophysics
Background:
- Cytochrome c oxidase is the terminal enzyme in the respiratory chain, crucial for cellular energy production.
- It facilitates proton pumping across the inner mitochondrial membrane by reducing oxygen to water.
Purpose of the Study:
- To investigate the fundamental mechanisms of redox-coupled proton pumps at the single-molecule level.
- To understand the physical principles governing proton pumping efficiency.
Main Methods:
- Development of kinetic models at the single-molecule level.
- Analysis of electrostatic couplings and nonlinear gating mechanisms.
Main Results:
- Proton pumping against potentials >150 mV is achievable via electrostatic couplings with asymmetric charge centers.
- Nonlinear gates are essential for achieving high efficiency in real enzyme systems.
Conclusions:
- Fundamental requirements for proton pumping elucidated, suggesting evolutionary origins for cytochrome c oxidase.
- General design principles applicable to other molecular machines and bio-inspired fuel cells.
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