Enzyme-catalyzed oxidation of 17 β -estradiol using immobilized laccase from trametes versicolor

Abstract

Many natural and synthetic estrogens are amenable to oxidation through the catalytic action of oxidative enzymes such as the fungal laccase Trametes versicolor. This study focused on characterizing the conversion of estradiol (E using laccase that had been immobilized by covalent bonding onto silica beads contained in a bench-scale continuous-flow packed bed reactor. Conversion of Eaccomplished in the reactor declined when the temperature of the system was changed from room temperature to just above freezing at pH 5 as a result of a reduced rate of reaction rather than inactivation of the enzyme. Similarly, conversion increased when the system was brought to warmer temperatures. Econversion increased when the pH of the influent to the immobilized laccase reactor was changed from pH 7 to pH 5, but longer-term experiments showed that the enzyme is more stable at pH 7. Results also showed that the immobilized laccase maintained its activity when treating a constant supply of aqueous Eat a low mean residence time over a 12-hour period and when treating a constant supply of aqueous Eat a high mean residence time over a period of 9 days. © 2011 Chantale Cardinal-Watkins and Jim A. Nicell.