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Quantum electron tunneling in respiratory complex I.

Tomoyuki Hayashi¹, Alexei A Stuchebrukhov

¹Department of Chemistry, University of California, One Shields Avenue, Davis, California 95616, United States.

The Journal of Physical Chemistry. B

|April 19, 2011

Summary

We simulated electronic wiring in Complex I, revealing quantum tunneling is key for electron transfer between iron-sulfur clusters. Core electron polarization significantly slows transfer rates, impacting the respiratory chain.

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Analyzing Supercomplexes of the Mitochondrial Electron Transport Chain with Native Electrophoresis, In-gel Assays, and Electroelution

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Published on: June 1, 2017

Area of Science:

Biophysics
Quantum Chemistry
Enzymology

Background:

Complex I is crucial for cellular respiration.
Understanding electron transfer mechanisms is vital.
Iron-sulfur (Fe/S) clusters facilitate electron transport.

Purpose of the Study:

To simulate atomistic electronic wiring of Fe/S clusters in Complex I.
To investigate the role of quantum mechanical tunneling in electron transfer.
To analyze the impact of protein environment and electron polarization on transfer rates.

Main Methods:

Application of tunneling current theory for many-electron systems.
Broken-symmetry (BS) state calculations at the ZINDO level.
Simulation of electron tunneling pathways and energy levels.

Main Results:

One-electron tunneling approximation holds for Fe/S clusters.
Induced core electron polarization reduces electron transfer rates by 19-56%.
Quantum interferences observed, indicating wave properties of electrons.
Electron tunneling pathways involve up to three protein residues.
Calculated tunneling energy aligns with quantum mechanical tunneling theory.

Conclusions:

Quantum mechanical tunneling is the primary mechanism for electron transfer in Complex I.
Protein environment and electron polarization significantly modulate electron transfer efficiency.
Fluctuations in tunneling pathways are influenced by the local protein environment.
Simulated results agree with experimental observations on electron transfer rates.