Structure-dependent electrical conductivity of protein: its differences between alpha-domain and beta-domain...

Area of Science:

• Biophysics
• Molecular Electronics
• Protein Science

Background:

• Electron transport through protein domains is critical for biological functions and molecular electronics.
• Significant differences in electrical conductivity between protein domains are hypothesized but require experimental validation.

Purpose of the Study:

• To experimentally and theoretically investigate and compare electron transport efficiency in alpha-domains versus beta-domains of proteins.
• To elucidate the structural basis for observed differences in protein conductivity.

Main Methods:

• Scanning tunneling microscopy (STM) was used to measure the conductance of single hemoglobin (Hgb) alpha-domains and superoxide dismutase (SOD) beta-domains.
• First-principles calculations were employed to analyze molecular orbitals and theoretical conductivity.
• Comparative analysis of molecular structures and packing modes was performed.

Main Results:

• Hemoglobin's alpha-domain demonstrated significantly higher current signals compared to the beta-domain of superoxide dismutase, indicating greater conductivity.
• Theoretical calculations confirmed that both tunneling and hopping transport are more efficient in alpha-domains.
• Differences in molecular packing modes between alpha- and beta-domains were identified as the likely cause for conductivity variations.

Conclusions:

• Alpha-domains are demonstrably more conductive than beta-domains due to structural packing differences.
• The findings provide fundamental insights into structure-dependent electron transport in proteins.
• This research holds significant implications for the development of molecular electronic devices.