Study on Kinetic Behaviors of the Biocatalysis of Laccase on Oxidation of Phenolic Compounds——Using Catechol and Epicatechin as Model Substrates

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 408 nm,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 ℃,Km values for catechol and epicatechin were 0.279,0.145 mol/L,respectively;Vmax values were 0.114,0.139 A/(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 0.04 U/mL for substrate concentration 0.5 mol/L.