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Related Concept Videos

Electron Transport Chain Components01:29

Electron Transport Chain Components

The electron transport chain (ETC) is a crucial metabolic pathway that facilitates energy conversion in prokaryotic and eukaryotic cells. In eukaryotes, the ETC comprises four membrane-associated protein complexes in the inner mitochondrial membrane. In prokaryotes, the ETC in the plasma membrane can vary in composition, with fewer or different complexes depending on the organism and environmental conditions. These complexes transfer electrons from electron donors, such as NADH and FADH2, to...
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Translocation of Proteins into the Mitochondria

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Updated: Jun 13, 2026

Standards for Quantitative Metalloproteomic Analysis Using Size Exclusion ICP-MS
09:51

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Published on: April 13, 2016

Electron flow through metalloproteins.

Harry B Gray1, Jay R Winkler

  • 1Beckman Institute, California Institute of Technology, Pasadena, CA 91125, USA. hbgray@caltech.edu

Biochimica Et Biophysica Acta
|May 13, 2010
PubMed
Summary
This summary is machine-generated.

Biological electron transfer over long distances, up to 20 angstroms, occurs via tunneling and hopping. Sigma and hydrogen bonds mediate electron transfer, while tryptophan facilitates rapid hole hopping.

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Area of Science:

  • Biophysics
  • Biochemistry
  • Physical Chemistry

Background:

  • Electron transfer is crucial for biological energy processes like photosynthesis and respiration.
  • These processes often involve metal cofactors separated by significant molecular distances.

Purpose of the Study:

  • To investigate the mechanisms and rates of long-distance electron transfer in biological systems.
  • To understand how polypeptide structures mediate electronic coupling between redox centers.

Main Methods:

  • Utilized laser flash-quench triggering methods to initiate and monitor electron transfer.
  • Studied electron transfer in Ru-modified cytochromes and blue copper proteins in solution and crystalline states.
  • Analyzed electron transfer rates to elucidate mediating pathways.

Main Results:

  • Demonstrated microsecond timescale electron tunneling (up to 20 angstroms) between Fe(II)/Cu(I) and Ru(III) centers.
  • Identified sigma and hydrogen bonds within polypeptide structures as key mediators of electronic coupling.
  • Observed that hole hopping through tryptophan is significantly faster than single-step electron tunneling over 20 angstroms.

Conclusions:

  • Long-distance electron transfer in proteins is facilitated by specific structural elements like sigma and hydrogen bonds.
  • Multistep tunneling (hopping) provides an efficient pathway for rapid charge transport over extended molecular distances.
  • Tryptophan residues play a significant role in accelerating charge transport via hopping mechanisms.