title: Peculiarities of direct bioelectrocatalysis by laccase in aqueous-nonaqueous mixtures.
abstract: The effect of concentration of ethanol and dimethyl sulfoxide on the catalytic activity of laccase is studied for the enzymatic reaction of catechol oxidation and bioelectrocatalytic reaction of oxygen reduction under the conditions of direct electron transfer. Laccase-Nafion composite is elaborated ensuring the enzyme stability in a wide potential range and a content of organic solvents. Based on the STM measurements, the structure of composite layer is proposed. It is shown that the mechanism of oxygen reduction reaction by laccase in organo-aqueous mixtures is similar to that earlier proposed for aqueous solutions. A decrease in the electrocatalytic activity of laccase in the oxygen reduction correlates with a decrease in the laccase enzymatic activity in the substrate oxidation. However, a decrease in the laccase activity in the composite is observed at a higher content of organic solvent in the mixture. The mechanism of laccase inactivation by organic solvents is proposed.
authors.affiliation: Frumkin Institute of Electrochemistry, Russian Academy of Sciences, Leninskii pr. 31, Moscow 117071, Russia. bogd@elchem.ac.ru
authors.forename: V A
authors.initials: VA
authors.lastname: Bogdanovskaya
authors.forename: M R
authors.initials: MR
authors.lastname: Tarasevich
authors.forename: L N
authors.initials: LN
authors.lastname: Kuznetsova
authors.forename: M F
authors.initials: MF
authors.lastname: Reznik
authors.forename: E V
authors.initials: EV
authors.lastname: Kasatkin
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods*; D002384:Catalysis; D002396:Catechols / Q000737:chemistry; D004121:Dimethyl Sulfoxide / Q000737:chemistry*; D004563:Electrochemistry / Q000379:methods*; D004566:Electrodes; D004789:Enzyme Activation; D004791:Enzyme Inhibitors; D004795:Enzyme Stability; D004800:Enzymes, Immobilized / Q000737:chemistry; D000431:Ethanol / Q000737:chemistry*; D005465:Fluorocarbon Polymers; D042845:Laccase; D009930:Organic Chemicals / Q000737:chemistry; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000037:antagonists & inhibitors / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry; D012680:Sensitivity and Specificity; D012997:Solvents / Q000737:chemistry; D014867:Water / Q000737:chemistry*
chemical_list: D002396:Catechols; D004791:Enzyme Inhibitors; D004800:Enzymes, Immobilized; D005465:Fluorocarbon Polymers; D009930:Organic Chemicals; D012997:Solvents; D014867:Water; C040402:perfluorosulfonic acid; D000431:Ethanol; D010088:Oxidoreductases; D042845:Laccase; C034221:catechol; D010100:Oxygen; D004121:Dimethyl Sulfoxide