Linked Enzyme Aggregates Research Articles

Baeyer–Villiger oxidation with peracid generated in situ by CaLB-CLEA catalyzed perhydrolysis

Candida antarctica lipase B, immobilized as cross linked enzyme aggregates (CLEAs) was used to mediate the Baeyer-Villiger oxidation of cyclohexanone to epsilon-caprolactone, and the reaction was compared with the one using Novozym (R) 435 as catalyst. The conversion was dependent on the initial concentration of cyclohexanone, and was about 90% after 48 h at concentrations of up to 0.25 M but was decreased at higher concentrations. Caprolactone concentrations up to 0.6 M had no effect on the reaction efficiency. Among the cyclic ketones tested, the highest degree of conversion was achieved for cyclopentanone (88%) and the lowest for cyclooctanone (about 2%). The effect of methyl substitution and position of substitution on the cycloketone was studied using methylcyclohexanone and it has shown to influence the conversion efficiency. Both hydrogen peroxide and the reaction by-product acetic acid had a deleterious effect on the stability of the biocatalyst. (C) 2012 Elsevier B.V. All rights reserved. (Less)

A new application of supercritical CO2 technology for cross linked enzyme aggregates

A new application of supercritical CO2 technology for cross linked enzyme aggregates

Porous cross linked enzyme aggregates (p-CLEAs) of Saccharomyces cerevisiae invertase

In this work, porous cross-linked enzyme aggregates (p-CLEAs) of Saccharomyces cerevisiae invertase are reported for the first time. Porous CLEAs were prepared by adding starch as a pore-making agent in crude invertase solution and co-precipitating with invertase using ammonium sulfate as a precipitating agent. The resultant co-precipitate was cross-linked for 8 h with 20 mM glutaraldehyde and in the end starch was removed by alpha amylase. The highest catalytic efficiency was obtained at 0.4% (w/v) starch. The scanning electron microscopy analysis of invertase p-CLEAs showed a porous structure. The p-CLEAs were shown to have improved internal mass transfer compared to conventional CLEAs.

Different Methods of Acid Phosphatase Immobilization for Its Application in FIA Systems with Potentiometric Detection

Abstract Application of enzymatic catalysis in chemical analysis enables increase of selectivity, reduction of detection limits, lowering of analysis costs and duration. Enzymes in flow through analytical systems can be applied in two main configurations [1]. In the first of them, enzymes are immobilized on special carriers in flow-through reactor. The second possible configuration are biosensors (working as detectors), in which enzyme molecules are an integral part of sensor receptor layer. In both cases, enzyme immobilization is necessary to ensure multiple use of applied system. In presented work the possibility of application of novel fluoride selective electrodes, as detector in FIA systems utilizing enzymatic reactions in various configurations has been evaluated. Different methods of enzyme (Acid Phosphatase, EC 3.1.3.2) immobilization have been tested, including covalent bonding via -NH2 and -COOH groups (both on ion exchanger resin and sensor membrane) and cross linking with glutaraldehyde (CLEAs, cross linked enzyme aggregates).

Azo dye decolorization by optimized cross linked enzyme aggregates (CLEAs) of a royal palm ( Roystonea regia) peroxidase

Azo dye decolorization by optimized cross linked enzyme aggregates (CLEAs) of a royal palm ( Roystonea regia) peroxidase