Abstract
In this study, an immobilization strategy for magnetic cross-linking enzyme aggregates of lipase B from Candida antarctica (CALB) was developed and investigated. Magnetic particles were prepared by conventional co-precipitation. The magnetic nanoparticles were modified with 3-aminopropyltriethoxysilane (APTES) to obtain surface amino-functionalized magnetic nanoparticles (APTES–Fe3O4) as immobilization materials. Glutaraldehyde was used as a crosslinker to covalently bind CALB to APTES–Fe3O4. The optimal conditions of immobilization of lipase and resolution of racemic 1-phenylethanol were investigated. Under optimal conditions, esters could be obtained with conversion of 50%, enantiomeric excess of product (eep) > 99%, enantiomeric excess of substrate (ees) > 99%, and enantiomeric ratio (E) > 1000. The magnetic CALB CLEAs were successfully used for enzymatic kinetic resolution of fifteen secondary alcohols. Compared with Novozym 435, the magnetic CALB CLEAs exhibited a better enantioselectivity for most substrates. The conversion was still greater than 49% after the magnetic CALB CLEAs had been reused 10 times in a 48 h reaction cycle; both ees and eep were close to 99%. Furthermore, there was little decrease in catalytic activity and enantioselectivity after being stored at −20 °C for 90 days.
Highlights
Biocatalysts have attracted more attention over the past few decades due to their broad substrate specificity, excellent selectivity, mild reaction conditions, environmental friendliness, and so on.Especially for enzymatic resolution, they provide an effective and facile route for the preparation of chiral compounds using lipase as a catalyst [1,2].Lipase B from Candida antarctica (CALB) is one of the most popular and widely used lipases [3].Its remarkable ability to catalyze a wide range of reactions, such as ammonolysis, transesterification, and esterification, is due to its excellent chemo, regio, and stereoselective properties [4,5,6,7]
Enantiospecific transesterification of racemic 1-phenylethanol with vinyl acetate was selected as the model reaction and was used to evaluate the catalytical efficiency of immobilized lipase; the result was compared to free CALB
Enantiospecific transesterification of racemic 1-phenylethanol with vinyl acetate was selected as the model reaction and was used to evaluate the catalytical efficiency of immobilized lipase, which was compared to free CALB and Novozym 435
Summary
Biocatalysts have attracted more attention over the past few decades due to their broad substrate specificity, excellent selectivity, mild reaction conditions, environmental friendliness, and so on.Especially for enzymatic resolution, they provide an effective and facile route for the preparation of chiral compounds using lipase as a catalyst [1,2].Lipase B from Candida antarctica (CALB) is one of the most popular and widely used lipases [3].Its remarkable ability to catalyze a wide range of reactions, such as ammonolysis, transesterification, and esterification, is due to its excellent chemo-, regio-, and stereoselective properties [4,5,6,7]. Biocatalysts have attracted more attention over the past few decades due to their broad substrate specificity, excellent selectivity, mild reaction conditions, environmental friendliness, and so on. For enzymatic resolution, they provide an effective and facile route for the preparation of chiral compounds using lipase as a catalyst [1,2]. Lipase B from Candida antarctica (CALB) is one of the most popular and widely used lipases [3]. Its remarkable ability to catalyze a wide range of reactions, such as ammonolysis, transesterification, and esterification, is due to its excellent chemo-, regio-, and stereoselective properties [4,5,6,7]. Like every other free enzyme, it is associated with several drawbacks, such as low stability, difficulty in product separation, and in recycling [8]. Immobilization is one of the important and efficient ways to overcome these disadvantages [1,9,10,11,12]
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