Abstract: Trametes versicolor laccase was employed to measure enzymatic kinetics parameters for oxidation of model substrates, namely catechol and epicatechin. The results showed that the maximum absorption wavelengths of laccase-catalyzed oxidation end-products from catechol and epicatechin were 388 and 408nm, respectively; Optimum pH values were 5.5 and 5.75, respectively; Optimum reaction temperatures were both 55℃, and laccase-catalyzed oxidations for both substrates fitted the Michaelis-Menten equation. Under the reaction temperature of 25℃, K_malues for catechol and epicatechin were 0.279, 0.145mol/L, respectively; V_max values were 0.114, 0.139A/(U·min), respectively. This indicates that the catalytic activity of laccase on oxidation of epicatechin is much more higher than that of catechol. For the bio-transformation of mixture from the 2 substrates, enzyme dosage for catechol should be adopted which is 0.04U/mL for substrate concentration 0.5mol/L.

Key words: laccase, biocatalysis, catechol, epicatechin, kinetics behavior