Abstract
Sol-gel entrapment is an efficient immobilization technique that allows preparation of robust and highly stable biocatalysts. Lipase from Candida antarctica B was immobilized by sol-gel entrapment and by sol-gel entrapment combined with adsorption on Celite 545, using a ternary silane precursor system. After optimization of the immobilization protocol, the best enzyme loading was 17.4 mg/g support for sol-gel entrapped lipase and 10.7 mg/g support for samples obtained by entrapment and adsorption. Sol-gel immobilized enzymes showed excellent values of enantiomeric ratio E and activity when ionic liquid 1-octyl-3-methyl-imidazolium tetrafluoroborate was used as additive. Immobilization increased the stability of the obtained biocatalysts in several organic solvents. Excellent operational stability was obtained for the immobilized lipase, maintaining unaltered catalytic activity and enantioselectivity during 15 reuse cycles. The biocatalysts were characterized using scanning electron microscopy (SEM) and fluorescence microscopy. The improved catalytic efficiency of entrapped lipases recommends their application for large-scale kinetic resolution of optically active secondary alcohols.
Highlights
The use of biocatalytic reactions is an important approach to synthesize pharmaceutical products and fine chemicals [1,2,3,4]
Lipase-catalyzed reactions in organic solvents are becoming increasingly important in enantioselective synthetic chemistry, as certain reactions which are sensitive to water can be carried out in organic media [6,7,8,9,10,11,12]
We investigated the enzymatic preparations that previously showed excellent reusability and stability properties
Summary
The use of biocatalytic reactions is an important approach to synthesize pharmaceutical products and fine chemicals [1,2,3,4]. Reactions catalyzed by various types of hydrolases are predominant among biotransformations. Among hydrolytic enzymes lipases and esterases are frequently used because they accept a broad range of substrates and often exhibit high enantioselectivity. There are a large number (>50) of commercial lipases and esterases currently available for biocatalytic reactions. Lipase-catalyzed reactions in organic solvents are becoming increasingly important in enantioselective synthetic chemistry, as certain reactions which are sensitive to water can be carried out in organic media [6,7,8,9,10,11,12]
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