Coherent Electron Transfer in Cytochrome Nanowires at 300 K

Area of Science:

• Computational biophysics
• Electron transfer mechanisms
• Microbial nanowires

Background:

• Cytochrome OmcZ and OmcS function as biological "nanowires" facilitating extracellular electron transfer.
• Understanding electron transfer dynamics in these proteins is crucial for bioenergetics and nanotechnology.
• Previous studies lack detailed computational insights into the quantum mechanical aspects of this process.

Purpose of the Study:

• To computationally investigate the mechanism of electron transfer in cytochrome OmcZ and OmcS nanowires.
• To elucidate the role of quantum mechanical effects, including vibronic coupling and fluctuating energies, in electron transport.
• To compare the electron transfer efficiency between OmcZ and OmcS.

Main Methods:

• Integration of the quantum-mechanical stochastic Liouville equation with molecular dynamics simulations.
• Inclusion of fluctuating energies and interaction matrix elements from molecular dynamics.
• Detailed treatment of vibronic coupling to model electron transfer dynamics.

Main Results:

• Electron density oscillates rapidly between adjacent hemes, occurring faster than thermal equilibration.
• Coherent electron density waves travel approximately 60 Å, exceeding the length of protein subunits.
• Calculated electron flow rates underestimate experimental values but correctly show faster long-range electron diffusion in OmcZ compared to OmcS.

Conclusions:

• Quantum coherence plays a significant role in enabling efficient long-range electron transfer in microbial nanowires.
• The computational model provides valuable insights into the dynamics of electron transfer, highlighting differences between OmcZ and OmcS.
• This study advances the understanding of biological electron transport and its potential applications.