title: Interactions of glucose oxidase with various metal polypyridine complexes as mediators of glucose oxidation.
abstract: The interaction between glucose oxidase (GOx) and a typical metal complex, which is chemically stable in both oxidized and reduced forms, has been investigated by a voltammetric method. The evaluation of an electron-transfer mediator useful for glucose oxidation is discussed from thermodynamic and kinetic points of view, i.e. the redox potentials of various metal complexes and the second-order rate constants for the electron transfer between GOx in reduced form and the metal complexes in oxidized form. No mediation of glucose oxidation by [Co(bpy)(3)](2+) (bpy=2,2'-bipyridine) or [Cu(bpy)(2)](2+) occurred, in spite of their appropriate redox potentials. This was attributed mainly to the lower electron-self-exchange rates of the mediator and the reaction with GOx. All three types of osmium(II) complexes, [Os(PP) (n)](2+) ( n=2 or 3; PP=polypyridine), [OsL(2)(PP)(2)](2+) (L=imidazole and its derivatives), and [OsClL(bpy)(2)](+), acted as excellent electron-transfer mediators for the glucose oxidation. Mixed ligand complexes, [OsL(2)(PP)(2)](2+) and [OsClL(bpy)(2)](+), have been concluded to be more efficient electron-transfer mediators. The electron-transfer rates between the mediator and GOx have been found to be accelerated by intermolecular electrostatic interactions or hydrogen bonds.
authors.affiliation: Unit of Chemistry, Faculty of Engineering, Kansai University, 3-3-35 Yamate-cho, Suita, Osaka 564-8680, Japan.
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Nakabayashi
authors.forename: Kazuyo
authors.initials: K
authors.lastname: Nakamura
authors.forename: Mayuko
authors.initials: M
authors.lastname: Kawachi
authors.forename: Takeshi
authors.initials: T
authors.lastname: Motoyama
authors.forename: Osamu
authors.initials: O
authors.lastname: Yamauchi
mesh_terms: D004563:Electrochemistry / Q000379:methods; D005182:Flavin-Adenine Dinucleotide / Q000737:chemistry; D005947:Glucose / Q000032:analysis / Q000737:chemistry*; D005949:Glucose Oxidase / Q000737:chemistry*; D007700:Kinetics; D008024:Ligands; D008670:Metals / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry*; D017892:Osmium Compounds / Q000737:chemistry; D009994:Osmolar Concentration; D010084:Oxidation-Reduction; D011725:Pyridines / Q000737:chemistry*; D012965:Sodium Chloride / Q000737:chemistry
chemical_list: D008024:Ligands; D008670:Metals; D009942:Organometallic Compounds; D017892:Osmium Compounds; D011725:Pyridines; D005182:Flavin-Adenine Dinucleotide; D012965:Sodium Chloride; D005949:Glucose Oxidase; D005947:Glucose; C023666:pyridine