Immobilized Enzymes and Enzyme Technology

We shall end this chapter by giving examples of a growing technology where enzymes are anchored to a solid matrix and used to perform specific transformation of biomaterials. The enzyme of interest is covalently attached to a carrier polymer by a spacer molecule. 

The inert carrier could be a polyurethane or other types of resin or a natural polymer such as collogen, easily available from animal skin. A 

An important feature of this procedure is that addition of the enzyme to the reaction mixture during the formation of the gel minimizes enzyme deactivation. Furthermore, covalent incorporation of the enzyme into the gel provides some protection against proteases. Second, the procedure is simple and of general use and should be directly applicable to a variety of enzyme systems as well as immobilization of whole cells and organelles. Finally, the gel can be rendered susceptible to magnetic filtration by including a ferrofluid in the gel formation step. 

It is important to realize that developing methods for stabilizing the enzyme in its native form is also a major goal in this field (123). Successful progress along these lines have been obtained recently by the use of bifunctional reagents to cross-link the peptide chains within the enzyme tertiary structure. 

Cross-linking prevents denaturation from occurring under the severe conditions of manipulation and keeps the active site region intact. The most used cross-linking agents are imino esters. By reacting with available lysine side chains, amide bonds are eventually formed between two sections of the polypeptide chain. 

---