title: Direct electron transfer to a metalloenzyme redox center coordinated to a monolayer-protected cluster.
abstract: A strategy for establishing electrical contact to the metal center of a redox metalloenzyme, galactose oxidase (GOase), by coordination of a linker attached to a monolayer-protected gold cluster is presented. The cluster-enzyme hybrid system was first prepared in solution and characterized by high-angle annular dark-field scanning transmission electron microscopy. Electrochemical communication between a gold electrode and GOase was achieved by first modifying the electrode surface with a biphenyl dithiol self-assembled monolayer followed by reaction with gold clusters capped with thioctic acid. GOase was then immobilized by replacement of the H(2)O molecule at the Cu(II) exogenous site by coordination of a carboxylate-terminated gold cluster. This chemical attachment ensured electrical contact between the redox center and the electrode, leading to direct mediatorless electron transfer to the protein. Hybrid systems can find applications in biosensors and biofuel cells and for studying electrochemically the catalytic mechanism of reactions for which free radicals and electron-transfer reactions are involved. The present results can be extended to other metalloenzymes.
authors: Chemistry Department, University of Liverpool, Liverpool L69 7ZD, United Kingdom. J.Abad-Pastor@liv.ac.uk
authors: Jose M
authors: JM
authors: Abad
authors: Mhairi
authors: M
authors: Gass
authors: Andrew
authors: A
authors: Bleloch
authors: David J
authors: DJ
authors: Schiffrin
mesh_terms: D001203:Ascomycota / Q000201:enzymology; D004566:Electrodes; D004579:Electron Transport; D005692:Galactose Oxidase / Q000737:chemistry* / Q000378:metabolism*; D006046:Gold / Q000737:chemistry / Q000378:metabolism*; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism*; D010084:Oxidation-Reduction; D013499:Surface Properties; D008063:Thioctic Acid / Q000737:chemistry
chemical_list: D009942:Organometallic Compounds; D008063:Thioctic Acid; D006046:Gold; D005692:Galactose Oxidase