Basics of Enzyme Immobilization
Immobilization of enzymes is not a new concept but one that has been around for over 100 years. However, wide applications for immobilized enzymes came only in the past four decades in the form of synthesis of various complex drug intermediates; chemical
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Basics of Enzyme Immobilization
2.1 Introduction Immobilization of enzymes is not a new concept but one that has been around for over 100 years. However, wide applications for immobilized enzymes came only in the past four decades in the form of synthesis of various complex drug intermediates; chemical synthesis under mild conditions without production of toxic by-products; remediation of polluted water, air and soil by removal of recalcitrant pollutant in an effective way; disease diagnosis; and correction of various genetic diseases due to the absence of metabolic enzymes, etc. In its immobilized state, an enzyme has convenient handling, provides easier product separation by eliminating protein contaminants, has reusability (useful particularly for costly enzymes), higher stability under extreme physical and chemical conditions, easier shipment of enzyme from one place to another, makes the complete process more viable economically, is applicable for all types of reactors (e.g., continuous, fixed-bed) with varied interior design, and provides easier process control [90, 91]. Thus, immobilized enzymes are adaptable for all type of industrial processes. Furthermore, enzyme immobilization is useful for multienzyme and chemoenzymatic cascade processes [92]. In its lyophilized state (i.e. freeze-dried powders), enzymes have various properties that are similar to immobilized enzymes such as stability during storage, easier shipment, and not being affected by the presence of an extreme physicochemical environment. However, once solubilized in appropriate media it resembles completely to a soluble enzyme, which is associated with the problem of product contamination with the enzyme molecules and not allowing enzyme reusability. Furthermore, lyophilization is not applicable for all types of enzymes [93]. In addition to enzyme immobilization, there are various other techniques available that also permit improvement in the enzyme features, including recombinant DNA technology, protein engineering, high throughput technology, genomics and proteomics. The combination of recombinant DNA and protein engineering have © Springer International Publishing Switzerland 2016 A. Dwevedi, Enzyme Immobilization, DOI 10.1007/978-3-319-41418-8_2
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2 Basics of Enzyme Immobilization
been significantly helpful for large-scale enzyme production with desirable properties. Protein engineering using techniques like site-directed mutagenesis and in vitro evolution via gene shuffling has helped in enzyme manipulation to exhibit desired properties (e.g., chemoselectivity, regioselectivity, stereoselectivity long-term stability, activity in the presence of high substrate concentrations, and tolerance towards organic solvents). However, these techniques are laborious, costly, lack long-term operational stability, and are difficult for enzyme recovery and reusability. These drawbacks can be overcome by enzyme promiscuity as a result of immobilization. Debate on enzyme immobilization has also raised various issues such as lowering enzyme activ
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