Techniques for Preparation of Cross-Linked Enzyme Aggregates and Their Applications in Bioconversions

Abstract

Enzymes are biocatalysts. They are useful in environmentally friendly production processes and have high potential for industrial applications. However, because of problems with operational stability, cost, and catalytic efficiency, many enzymatic processes have limited applications. The use of cross-linked enzyme aggregates (CLEAs) has been introduced as an effective carrier-free immobilization method. This immobilization method is attractive because it is simple and robust, and unpurified enzymes can be used. Coimmobilization of different enzymes can be achieved. CLEAs generally show high catalytic activities, good storage and operational stabilities, and good reusability. In this review, we summarize techniques for the preparation of CLEAs for use as biocatalysts. Some important applications of these techniques in chemical synthesis and environmental applications are also included. CLEAs provide feasible and efficient techniques for improving the properties of immobilized enzymes for use in industrial applications.

A Middle-Aged Enzyme Still in Its Prime: Recent Advances in the Field of Cutinases

“…The most important is the increase of the operational stability, and hence the reusability of the biocatalyst, which reduces the cost of an industrial process. There are several immobilization methods on various types of solid supports that are achieved by adsorption, entrapment, and non-covalent and covalent binding [77]. The immobilization of enzymes may affect properties other than their stability, namely, activity, specificity, or selectivity.…”

“…Carrier-free immobilization procedures by the cross-linking of proteins have proven to be a cheaper alternative, since the high cost of carriers is circumvented [77]. Cross-linked enzyme aggregates (CLEAs) are usually prepared by the cross-linking of precipitated enzyme preparations using glutaraldehyde.…”

Immobilized Biocatalysts

“…Hitaishi et al [48] review all the factors influencing a proper orientation together with various analytical methods for characterization and quantification of the desired orientation. The review contributed by Yamaguchi and colleagues [49] deals with techniques for the preparation of cross-linked enzyme aggregates (CLEAs), including co-immobilization of different enzymes. CLEAs often combine the advantages of immobilized enzymes such as high catalytic activities, good storage, and operational stabilities, as well as good reusability.…”

Hollow zeolite microspheres as a nest for enzymes: a new route to hybrid heterogeneous catalysts

“…The presented aerosol method allows preparing hierarchical hollow zeolite structures using an easy, continuous, and scalable aerosol process. 53 The spheres can be loaded with the enzymes which are then crosslinked 54,55 to secure their entrapment and avoid their subsequent leaching. 56,57 Thus, the hollow microspheres are used both as epoxidation catalysts and as vessels for the enzyme.…”