Thai rice bran lipase-catalysed polyesterification : a development for practical applications

Abstract

Two systems of Thai rice bran lipase (Thai RBL)-catalysed aliphatic polyester synthesis in toluene, i.e., adipic acid and 1,4-butanediol, and adipic acid and poly(ethylene glycol) MW. 200, were earned out at stoichiometric ratio. The degree of polymerization was found to be 4 and 9 in the former case and 2 and 6 in the latter case. The polymerization was accelerated by the reaction temperature at 80⁰ to 100 ℃ and long reaction time for over 7 days. Thai RBL was immobilized via physisorption and covalent bonding to improve enzyme activity. The physisorption of Thai RBL onto fumed silica was optimized at 1:40 for carrier:crude enzyme (g/mL) to give 38% immobilization with hydrolytic activity of 21 mU/mg. The covalent bonding of Thai RBL onto fumed silica was achieved at 50% immobilization with hydrolytic activity of 9 mU/mg. The utilization of purified enzyme to immobilize by physisorption and covalent bonding improved the hydrolytic activity for three times comparing to that of crude enzyme.