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Updated: Jul 31, 2026
09:27
Protein Crystallization for X-ray Crystallography
Published on: January 17, 2011
Electron tunneling in protein crystals
F A Tezcan1, B R Crane, J R Winkler
1Beckman Institute, MC 139-74, California Institute of Technology, Pasadena, CA 91125, USA.
Summary
Electron tunneling rates between proteins in crystals match intraprotein transfer, revealing van der Waals and hydrogen bonds facilitate electron flow across interfaces.
Area of Science:
- Biophysics
- Protein Crystallography
- Electron Transfer
Background:
- Understanding electron tunneling through proteins is limited by fixed donor-acceptor systems.
- Factors controlling interprotein electron flow are unclear due to structural uncertainties.
Purpose of the Study:
- To investigate electron transfer kinetics between proteins in a crystalline environment.
- To resolve structural ambiguities in interprotein electron transfer.
Main Methods:
- Studied oxidation-reduction reactions in protein crystals.
- Measured electron transfer rates between native and Zn-substituted tuna cytochrome c (cyt c) in crystals of known structure.
Main Results:
- Electron transfer rates between Zn-cyt c and Fe(III)-cyt c (320 s⁻¹) and Fe(II)-cyt c and Zn-cyt c⁺ (2000 s⁻¹) were measured.
- Observed rates over a 24.1 Å distance closely matched intraprotein electron tunneling rates.
- Identified van der Waals interactions and water-mediated hydrogen bonds as effective coupling elements.
Conclusions:
- Protein crystals provide a method to overcome structural ambiguities in studying interprotein electron transfer.
- Van der Waals forces and hydrogen bonds facilitate electron tunneling across protein-protein interfaces.
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