Journal of Electroanalytical Chemistry, Vol.461, No.1-2, 174-183, 1999
Kinetic behaviour of dopamine polyphenol oxidase on electrodes of tetrathiafulvalenium tetracyanoquinodimethanide and tetracyanoquinodimethane species
This paper presents a study of the electrochemical behaviour of polyphenol oxidase onto-conducting organic salt electrodes using dopamine as enzymatic substrate. The enzyme is immobilized behind a dialysis membrane. TTF.TCNQ and carbon paste with TCNQ(0) and NaTCNQ are employed, and the role of the different salt components as enzyme regeneration mediators is analysed under anaerobic conditions. It: is concluded that both TCNQ(0) and NaTCNQ species are able to regenerate the active enzyme although chemical reactions between the species make it difficult to discriminate their behaviour. Results strongly suggest a heterogeneous mechanism for the enzymatic reaction and NaTCNQ as enzymatic regenerator on TTF.TCNQ, apparent Michaelis-Menten constants are evaluated. The results clearly point to an enzymatic control of the reaction rate under our experimental conditions. A chemical catalytic effect due to coupled chemical reactions is also described. The biosensors analysed are potentially useful from the analytical point of view. Different electrode materials were analysed: TTF.TCNQ and carbon paste with TCNQ(0) and NaTCNQ.
Keywords:AMPEROMETRIC ENZYME ELECTRODES;ELECTROCHEMICAL-BEHAVIOR;GLUCOSE-OXIDASE;SALT ELECTRODES;AQUEOUS-MEDIA;BIOSENSOR;IMMOBILIZATION;OXIDATION;XANTHINE