title: Coupling coherence distinguishes structure sensitivity in protein electron transfer.
abstract: Quantum mechanical analysis of electron tunneling in nine thermally fluctuating cytochrome b562 derivatives reveals two distinct protein-mediated coupling limits. A structure-insensitive regime arises for redox partners coupled through dynamically averaged multiple-coupling pathways (in seven of the nine derivatives) where heme-edge coupling leads to the multiple-pathway regime. A structure-dependent limit governs redox partners coupled through a dominant pathway (in two of the nine derivatives) where axial-ligand coupling generates the single-pathway limit and slower rates. This two-regime paradigm provides a unified description of electron transfer rates in 26 ruthenium-modified heme and blue-copper proteins, as well as in numerous photosynthetic proteins.
authors.affiliation: Departments of Chemistry and Biochemistry, Duke University, Durham, NC 27708, USA.
authors.forename: Tatiana R
authors.initials: TR
authors.lastname: Prytkova
authors.forename: Igor V
authors.initials: IV
authors.lastname: Kurnikov
authors.forename: David N
authors.initials: DN
authors.lastname: Beratan
mesh_terms: D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003198:Computer Simulation; D003573:Cytochrome b Group / Q000737:chemistry* / Q000378:metabolism*; D045304:Cytochromes c / Q000737:chemistry; D004579:Electron Transport; D006639:Histidine / Q000737:chemistry; D006860:Hydrogen Bonding; D008024:Ligands; D008433:Mathematics; D008956:Models, Chemical; D008958:Models, Molecular; D010084:Oxidation-Reduction; D011487:Protein Conformation; D017510:Protein Folding; D012428:Ruthenium
chemical_list: D003573:Cytochrome b Group; D008024:Ligands; D006639:Histidine; D012428:Ruthenium; D045304:Cytochromes c