FIG. 7.

Inhibition of laccase-catalyzed 3-HAA oxidation in the presence of purified P. cinnabarinus CDH II and cellobiose. (A) 3-HAA oxidation by laccase in a reaction mixture containing 500 μM 3-HAA, 0.15 U of laccase, and 0.12 U of CDH II in 1,000 μl of 50 mM sodium tartrate (pH 4.5) was monitored by determining changes in absorbance at 450 nm (——). The times at which 10 μl of cellobiose (final concentration, 500 μM) was added to the reaction mixture are indicated by arrows. Control experiments were performed without cellobiose (– – – –). (B) Hypothetical reaction mechanism for laccase-mediated oxidation of 3-HAA to CA (adapted from references 10 and 43 with permission from the publisher). (C) Effects of different concentrations of CDH II on the oxidation of 3-HAA (500 μM) by laccase (0.15 U) in 50 mM sodium tartrate (pH 4.5) containing 2 mM cellobiose. The control contained no CDH II and the amounts of CDH II that were added to the reaction mixtures were 0.015, 0.03, 0.06, 0.12, 0.18, 0.25, and 0.3 U.