Decaheme Cytochrome MtrF Adsorption and Electron Transfer on Gold Surface

Emergent electrical properties of multiheme cytochromes have promising applications. We performed hybrid simulations (molecular dynamics, free energy computation, and kinetic Monte Carlo) to study decaheme cytochrome, MtrF adsorption on an Au (111) surface in water and the electron transfer (ET) efficiency. Our results reveal that the gold surface's dehydration serves as a crucial driving force for protein adsorption due to large surface tension. The most possible adsorption orientation is with the ET terminal (heme5) approaching the gold surface, which yields a pathway for ET between the substrate and the aqueous environment. Upon adsorption, protein's secondary structures and central domains (II and IV) bonded with heme-residues remain relatively stable. MtrF surface mobility is dictated by thiol-gold interaction and strong binding between Au(111) and peptide aromatic groups. ET transfer rate across protein heme-network along the solvent-to-surface direction is slightly larger than that of the reverse direction, but lower than that of the solvation structure.