title: The nature of aqueous tunneling pathways between electron-transfer proteins.
abstract: Structured water molecules near redox cofactors were found recently to accelerate electron-transfer (ET) kinetics in several systems. Theoretical study of interprotein electron transfer across an aqueous interface reveals three distinctive electronic coupling mechanisms that we describe here: (i) a protein-mediated regime when the two proteins are in van der Waals contact; (ii) a structured water-mediated regime featuring anomalously weak distance decay at relatively close protein-protein contact distances; and (iii) a bulk water-mediated regime at large distances. Our analysis explains a range of otherwise puzzling biological ET kinetic data and provides a framework for including explicit water-mediated tunneling effects on ET kinetics.
authors.affiliation: Departments of Chemistry and Biochemistry, Duke University, Durham, NC 27708, USA.
authors.forename: Jianping
authors.initials: J
authors.lastname: Lin
authors.forename: Ilya A
authors.initials: IA
authors.lastname: Balabin
authors.forename: David N
authors.initials: DN
authors.lastname: Beratan
mesh_terms: D000818:Animals; D002417:Cattle; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D015786:Cytochromes b5 / Q000737:chemistry / Q000378:metabolism*; D004579:Electron Transport; D007700:Kinetics; D008956:Models, Chemical; D011166:Porphyrins / Q000737:chemistry; D011487:Protein Conformation; D013816:Thermodynamics; D014867:Water / Q000737:chemistry*
chemical_list: D011166:Porphyrins; D014867:Water; D015786:Cytochromes b5