Do multiheme cytochromes containing close-packed heme groups have a band structure formed from the heme π and π* orbitals?

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Abstract

Multiheme cytochromes (MHCs) are bacterial electron-transfer proteins. We show from optical spectra and calculations that some of these cytochromes probably contain occupied and unoccupied bands formed from heme π and π* orbitals that span the protein. In the fully oxidised proteins, the unoccupied π*-bands are energetically above the redox-active frontier orbitals, which according to NMR data and calculations, are formed of Fe3+ t2g and porphyrin π-orbitals. These orbitals on different hemes are electronically coupled according to EPR data and calculations, but only weakly so. We suggest a role for the heme bands in the electronic conductivity of single MHCs in bioelectronic junctions that is distinct from the role of the redox-active Fe3+ t2g and porphyrin π-orbitals in physiological electron transfer.
Original languageEnglish
Article number101556
JournalCurrent Opinion in Electrochemistry
Volume47
Early online date12 Jun 2024
DOIs
Publication statusPublished - Oct 2024

Keywords

  • Band structure
  • Bioelectronics
  • Cytochromes
  • Electron transfer
  • Electronic conductivity
  • Heme
  • Molecular orbitals
  • Spectroscopy

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