2000 Volume 26 Issue 6 Pages 882-886
The capabilities of Candida rugosa lipase, which was immobilized into organically modified silicates formed on kieselguhr such as Celite 545 are investigated in esterification of (-) -or (+) -menthol with butyric acid. In this study, we optimized the preparation conditions such as a molar ratio of precursors. From these investigations, we find that the optimized hybrid gel-immobilized lipase is derived from a mixture of dimethyldimethoxysilane and tetramethoxysilane at a molar ratio of 4: 1 and its enantioselectivity, which is defined as a ratio of the initial reaction rate of (-) -menthol to that of (+) -menthol, is enhanced up to 41 at 75°C. In addition, we observe the temperature dependence of these immobilized lipases. Consequently, the optimized hybrid gel-immobilized lipase shows higher activity than deposited lipase on Celite at all temperatures, and it is suggested that this activation results from a remarkable enhancement of the Vmax value.