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Spin-dependent electron transmission through bacteriorhodopsin embedded in purple membrane
Debabrata Mishra1, Tal Z Markus, Ron Naaman
1Departments of Chemical Physics and Organic Chemistry, Weizmann Institute, Rehovot 76100, Israel.
Summary
Electron transmission through bacteriorhodopsin (bR) membranes shows spin selectivity, with significant spin polarization observed. Protein structure critically influences conduction, dropping sharply upon denaturation.
Area of Science:
- Biophysics
- Materials Science
- Biochemistry
Background:
- Purple membrane contains bacteriorhodopsin (bR), a light-activated proton pump.
- Understanding electron transport in biological membranes is crucial for bioelectronic applications.
- Chiral biomolecules can exhibit unique electronic properties.
Purpose of the Study:
- To investigate spin-dependent electron transmission through bR-containing membranes.
- To explore the relationship between protein structure and electrical conduction.
- To assess the potential of bR for spin-selective electronic devices.
Main Methods:
- Spin-dependent photoelectron transmission spectroscopy.
- Spin-dependent electrochemical studies.
- Deposition of bR on various metallic and oxide substrates (gold, aluminum/aluminum-oxide, nickel).
- Protein denaturation to study structural effects on conduction.
Main Results:
- Observed spin selectivity in electron transmission through the bR membrane.
- Significant spin polarization (around 15%) detected, despite bR occupying only 10% of the membrane volume.
- Electrical conduction strongly depends on the protein's structural integrity.
- Denaturation of bR led to a substantial decrease in membrane conduction.
Conclusions:
- Bacteriorhodopsin membranes exhibit intrinsic spin selectivity in electron transport.
- The structural integrity of bR is essential for its conductive properties.
- These findings suggest potential applications for bR in spintronic devices and biosensors.
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