Applied Biochemistry and Biotechnology 2005-04-01

Characterization of sol-gel bioencapsulates for ester hydrolysis and synthesis.

Cleide M F Soares, Heizir F de Castro, Juliana E Itako, Flavio F de Moraes, Gisella M Zanin

Index: Appl. Biochem. Biotechnol. 121-124 , 845-59, (2005)

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Abstract

Candida rugosa lipase was entrapped in silica sol-gel particles prepared by hydrolysis of methyltrimethoxysilane and assayed by p-nitrophenyl palmitate hydrolysis, as a function of pH and temperature, giving pH optima of 7.8 (free enzyme) and 5.0-8.0 (immobilized enzyme). The optimum temperature for the immobilized enzyme (50-55 degrees C) was 19 degrees C higher than for the free enzyme. Thermal, operational, and storage stability were determined with n-butanol and butyric acid, giving at 45 degrees C a half-life 2.7 times greater for the immobilized enzyme; storage time was 21 d at room temperature. For ester synthesis, the optimum temperature was 47 degrees C, and high esterification conversions were obtained under repeated batch cycles (half-life of 138 h).