Immobilized enzyme
An immobilized enzyme is an enzyme, with restricted mobility, attached to an inert, insoluble material—such as calcium alginate (produced by reacting a mixture of sodium alginate solution and enzyme solution with calcium chloride). This can provide increased resistance to changes in conditions such as pH or temperature. It also lets enzymes be held in place throughout the reaction, following which they are easily separated from the products and may be used again - a far more efficient process and so is widely used in industry for enzyme catalysed reactions. An alternative to enzyme immobilization is whole cell immobilization. Immobilized enzymes are easily to be handled, simply separated from their products, and can be reused. Enzymes are bio-catalysts which play an essential role in the enhancement of chemical reactions in cells without being persistently modified, wasted, nor resulting in the loss of equilibrium of chemical reactions. Although the characteristics of enzymes are extremely unique, their utility in the industry is limited due to the lack of re-usability, stability, and high-cost of production. History The first synthetic immobilized enzyme was made in the 1950s, performed by the inclusion of enzyme into polymeric matrices or binding onto carrier substances. Also cross-linking procedure was applied by cross-linking of protein alone or along with the addition of inert materials. Over the last decade various immobilization methods have been developed. Binding the enzyme to previously synthesized carrier materials for example is the mostly preferred method so far. Newly, the procedure of cross-linking of crystals of enzyme is also considered as an exciting substitute. Utilization rate of immobilized enzymes is growing constantly. Considerations Before performing any kind of immobilization techniques, some factors should be in mind. It is necessary to understand the chemical and physical effects on an enzyme following immobilization. Enzyme stability and kinetic characteristics can be altered due to changes in the microenvironment conditions of the enzyme after entrapment, support material attachment, or products of enzymatic actions for instance. Additionally, it is important to consider maintaining the tertiary structure of an enzyme prior to immobilizing to have a functional enzyme. Similarly, another crucial site for the functionality of an enzyme is the active-site, which should also be maintained while enzyme is being attached to a surface for immobilization, it is a must to have a selective method for the attachment of surface/material to not end up with an immobilized, but dysfunctional enzyme. Consequently, there are three foundational factors to be thought of for the production of functional immobilized enzymes: immobilization supports selection, conditions and methods of immobilization. Support selection For a support material to be ideal, it must be hydrophilic, inert towards enzymes, biocompatible, microbial attack and compression resistant, and must be affordable. Support materials can be organic or inorganic, synthetic or natural (depending on the composition), since they are biomaterial types at the end. There is no universal type of a support material to be used for the immobilization of all enzymes. However, there are some commonly used supports such as silica-based carriers, acrylic