Voltammetric monitoring of laccase-catalysed mediated reactions.
Six different compounds capable of mediating laccase-catalysed reactions have been tested by cyclic voltammetry. They exhibited quasi-reversible electrodic behaviour with formal redox potentials ranging from 150 to 800 mV (E(0)' vs. SCE). The immersion of a laccase-coated glassy carbon electrode (GCE) in mediator solutions generated large cathodic catalytic currents easily recorded by cyclic voltammetry at low-potential scan rates. This current showed two well-defined pH profiles, which correlated with the variation of the mediator redox potentials at the pH range tested. The relevant effect of temperature on the activity of laccase has been assessed here. Likewise, it was shown that the current record varied with the substrate concentration. This trend fitted Michaelis-Menten kinetics, which allowed us to give an estimation of the affinity of the fungal laccase for the different mediators.
Fernández-Sánchez
César
C
Department of Textile Engineering, Campus de Azurem, University of Minho, 4800 Guimarães, Portugal.
Tzanov
Tzanko
T
Gübitz
Georg M
GM
Cavaco-Paulo
Artur
A
D001487:Basidiomycota / Q000201:enzymology*; D002384:Catalysis; D004563:Electrochemistry; D004579:Electron Transport; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D042845:Laccase; D008956:Models, Chemical; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000737:chemistry*; D019163:Reducing Agents / Q000737:chemistry*; D013816:Thermodynamics
D019163:Reducing Agents; D010088:Oxidoreductases; D042845:Laccase