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Electron flow through biological molecules: does hole hopping protect proteins from oxidative damage?
1Beckman Institute,California Institute of Technology,Pasadena,CA 91125,USA.
Quarterly Reviews of Biophysics
|November 6, 2015
Summary
Biological electron transfer occurs over long distances via tunneling and hole hopping. This mechanism, involving tyrosine and tryptophan chains, may protect enzymes like oxygenases from oxidative damage.
Area of Science:
- Biochemistry
- Biophysics
- Molecular Biology
Background:
- Biological electron transfers often involve metal cofactors separated by large distances.
- Understanding long-range electron transport is crucial for enzyme function and stability.
Purpose of the Study:
- To investigate mechanisms of long-range electron transfer in biological systems.
- To propose a protective role for hole hopping via tyrosine/tryptophan chains in enzymes.
Main Methods:
- Utilizing photosensitizer-modified iron and copper proteins to study electron tunneling.
- Analyzing enzyme structures (P450, TauD) to identify potential hole-transporting chains.
Main Results:
- Demonstrated single-step electron tunneling over 15-20 Å on nanosecond to microsecond timescales.
- Showed charge transport over longer distances via hole hopping through tyrosine and tryptophan residues.
Conclusions:
- Hole hopping through tyrosine/tryptophan chains is a viable mechanism for long-range charge transport.
- This mechanism may protect oxygenase, dioxygenase, and peroxidase enzymes from oxidative damage by dissipating excess energy.
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