Electron transfer and transport through multi-heme proteins: recent progress and future directions

Area of Science:

• Biophysics
• Electrochemistry
• Molecular Biology

Background:

• Multi-heme cytochromes (MHCs) are crucial biological molecules involved in electron transfer processes.
• Understanding electron transfer and transport mechanisms in MHCs is vital for bioelectronic applications.
• Recent advancements have provided new insights into the behavior of MHCs.

Purpose of the Study:

• To review recent experimental measurements and theoretical interpretations of electron transfer (ET) and electron transport (ETp) in MHCs.
• To highlight key experimental techniques used to probe these processes.
• To discuss the current understanding and remaining challenges in the field.

Main Methods:

• Pump-probe spectroscopy of ruthenium-labeled MHCs to determine heme-heme ET rates.
• Measurement of current-voltage (I-V) characteristics of MHCs in bioelectronic junctions.
• Theoretical modeling and interpretation of experimental data.

Main Results:

• The mechanism of electron transfer (ET) in MHCs in aqueous solution is well-established.
• Experimental data from spectroscopy and I-V measurements provide insights into ET rates and pathways.
• The electron transport (ETp) mechanism in bioelectronic junctions is less understood.

Conclusions:

• While electron transfer in solution is understood, electron transport through MHCs in bioelectronic junctions presents significant challenges.
• The complexity of the electrode-protein interface is a major factor limiting the understanding of ETp.
• Further research is needed to elucidate the ETp mechanisms in bioelectronic devices.