Electron tunneling through sensitizer wires bound to proteins

Area of Science:

• Biochemistry
• Theoretical Chemistry
• Biophysics

Background:

• Cytochrome P450 enzymes are crucial in metabolism and drug detoxification.
• Understanding electron transfer mechanisms is key to modulating P450 activity.
• Sensitizer wires provide a tool to probe electron transfer within enzyme active sites.

Purpose of the Study:

• To quantitatively analyze long-range electron transfer through sensitizer wires in cytochrome P450cam.
• To elucidate the role of bridging groups and molecular conformations in electron transfer efficiency.
• To provide a theoretical framework for interpreting experimental data and guiding future research.

Main Methods:

• Combined molecular dynamics (MD) simulations to capture dynamic protein-ligand interactions.
• Electronic coupling calculations to assess electron transfer pathways.
• Analysis of sensitizer wire conformations and their impact on electron transfer rates.

Main Results:

• Electron tunneling through perfluorinated aromatic bridges is enhanced by superexchange coupling.
• Aliphatic bridges facilitate electron flow via hole-mediated superexchange.
• Specific wire conformations with strong donor-acceptor couplings dominate electron transfer rates.
• Nuclear motion of the sensitizer wire significantly influences observed electron transfer rates.

Conclusions:

• The study provides a quantitative theoretical model for electron transfer in P450cam.
• Findings highlight the importance of both electronic and nuclear factors in electron transfer.
• The developed approach can be applied to other heme enzymes and aids in designing future experiments.