title: Long-range interfacial electron transfer of metalloproteins based on molecular wiring assemblies.
abstract: We address some physical features associated with long-range interfacial electron transfer (ET) of metalloproteins in both electrochemical and electrochemical scanning tunneling microscopy (ECSTM) configurations, which offer a brief foundation for understanding of the ET mechanisms. These features are illustrated experimentally by new developments of two systems with the blue copper protein azurin and enzyme nitrite reductase as model metalloproteins. Azurin and nitrite reductase were assembled on Au(111) surfaces by molecular wiring to establish effective electronic coupling between the redox centers in the proteins and the electrode surface for ET and biological electrocatalysis. With such assemblies, interfacial ET proceeds through chemically defined and well oriented sites and parallels biological ET. In the case of azurin, the ET properties can be characterized comprehensively and even down to the single-molecule level with direct observation of redox-gated electron tunnelling resonance. Molecular wiring using a pi-conjugated thiol is suitable for assembling monolayers of the enzyme with catalytic activity well-retained. The catalytic mechanism involves multiple-ET steps including both intramolecular and interfacial processes. Interestingly, ET appears to exhibit a substrate-gated pattern observed preliminarily in both voltammetry and ECSTM.
authors.affiliation: Department of Chemistry and Nano . DTU, Building 207, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark. cq@kemi.dtu.dk
authors.forename: Qijin
authors.initials: Q
authors.lastname: Chi
authors.forename: Jingdong
authors.initials: J
authors.lastname: Zhang
authors.forename: Palle S
authors.initials: PS
authors.lastname: Jensen
authors.forename: Hans E M
authors.initials: HE
authors.lastname: Christensen
authors.forename: Jens
authors.initials: J
authors.lastname: Ulstrup
mesh_terms: D000421:Alcaligenes / Q000737:chemistry; D001400:Azurin / Q000032:analysis / Q000737:chemistry*; D019245:Compressive Strength; D003198:Computer Simulation; D004553:Electric Conductivity; D004559:Electric Wiring; D004563:Electrochemistry / Q000379:methods*; D004579:Electron Transport; D008667:Metalloproteins / Q000032:analysis / Q000737:chemistry; D008956:Models, Chemical; D009572:Nitrite Reductases / Q000032:analysis / Q000737:chemistry*; D011550:Pseudomonas aeruginosa / Q000737:chemistry; D012666:Semiconductors; D013314:Stress, Mechanical; D013499:Surface Properties
chemical_list: D008667:Metalloproteins; D001400:Azurin; D009572:Nitrite Reductases