Immobilized enzyme

About: Immobilized enzyme is a research topic. Over the lifetime, 15282 publications have been published within this topic receiving 401860 citations.

Enzyme-Carrying Polymeric Nanofibers Prepared via Electrospinning for Use as Unique Biocatalysts

Abstract: Improvement of catalytic efficiency of immobilized enzymes via materials engineering was demonstrated through the preparation of bioactive nanofibers Bioactive polystyrene (PS) nanofibers with a typical diameter of 120 nm were prepared and examined for catalytic efficiency for biotransformations The nanofibers were produced by electrospinning functionalized PS, followed by the chemical attachment of a model enzyme, alpha-chymotrypsin The observed enzyme loading as determined by active site titration was up to 14% (wt/wt), corresponding to over 274% monolayer coverage of the external surface of nanofibers The apparent hydrolytic activity of the nanofibrous enzyme in aqueous solutions was over 65% of that of the native enzyme, indicating a high catalytic efficiency as compared to other forms of immobilized enzymes Furthermore, nanofibrous alpha-chymotrypsin exhibited a much-improved nonaqueous activity that was over 3 orders of magnitude higher than that of its native counterpart suspended in organic solvents including hexane and isooctane It appeared that the covalent binding also improved the enzyme's stability against structural denaturation, such that the half-life of the nanofibrous enzyme in methanol was 18-fold longer than that of the native enzyme

Efficient immobilization of lipases by entrapment in hydrophobic sol-gel materials.

Abstract: The commercial application of lipases as biocatalysts for organic synthesis requires simple but efficient methods to immobilize the enzyme, yielding highly stable and active biocatalysts which are easy to recover. In this study, we present a novel method to achieve lipase immobilization by entrapment in chemically inert hydrophobic silica gels which are prepared by hydrolysis of alkyl-substituted silanes in the presence of the enzyme. A typical immobilization procedure uses: an aqueous solution of lipase; sodium fluoride as a catalyst; and additives like polyvinyl alcohol or proteins and alkoxysilane derivatives like RSi-(OMe)3 with R = alkyl, aryl, or alkoxy as gel precursors. The effect of various immobilization parameters like stoichiometric ratio of water, silane, type and amount of additive, type and amount of catalyst, and type of silane has been carefully studied. The new method is applicable for a wide variety of lipases, yielding immobilized lipases with esterification activities enhanced by a factor of up to 88, compared to the commercial enzyme powders under identical conditions. Studies on the stability of sol-gel immobilized lipases under reaction conditions or storage (dry, in aqueous or organic medium) revealed an excellent retention of enzymatic activity. The possible reasons for the increased enzyme activities are discussed. © 1996 John Wiley & Sons, Inc.

Cross-linked enzyme aggregates (CLEAs): stable and recyclable biocatalysts.

Abstract: The key to obtaining an optimum performance of an enzyme is often a question of devising an effective method for its immobilization. In the present review, we describe a novel, versatile and effective methodology for enzyme immobilization as CLEAs (cross-linked enzyme aggregates). The method is exquisitely simple (involving precipitation of the enzyme from aqueous buffer followed by cross-linking of the resulting physical aggregates of enzyme molecules) and amenable to rapid optimization. We have shown it to be applicable to a wide variety of enzymes, including, in addition to a wide variety of hydrolases, lyases, e.g. nitrile hydratases and oxynitrilases, and oxidoreductases such as laccase and galactose oxidase. CLEAs are stable, recyclable catalysts exhibiting high catalyst productivities. Because the methodology is essentially a combination of purification and immobilization into one step, the enzyme does not need to be of high purity. The technique is also applicable to the preparation of combi-CLEAs, containing two or more enzymes, for use in one-pot, multistep syntheses, e.g. an oxynitrilase/nitrilase combi-CLEA for the one-pot conversion of benzaldehyde into (S)-mandelic acid, in high yield and enantiomeric purity.