Abstract
Thermomyces lanuginosus lipase (TLL) was immobilized on epoxy functionalized hydroxyl multi-walled carbon nanotube (MWCNT-OH) via an isocyanide-based multicomponent reaction. The immobilization process was carried out in deionized water (pH 7.0) at room temperature resulting in loading of 600 mg enzyme/g of support with specific activity 16.9 U/mg. An immobilization yield of 100% was obtained with the expressed activity 60%. The immobilized preparation exhibited an increased thermal stability with 49% residual activity at 75 °C compared with 19% for the free enzyme at the same temperature. Solvent stability in a high ratio of DMSO was improved from 52% in free TLL to 75% in immobilized TLL. The immobilized preparation was used for kinetic resolution of rac-ibuprofen through esterification of ibuprofen in isooctane as solvent. The best result was obtained with ethanol at 45 °C and molar ratio of 2.5:1 ethanol:ibuprofen in 1 ml isooctane with 99% ee(p) and E-value 300.