Bioconjugation for Enzyme Technology

Enzymes play important roles in all living cells. They possess remarkable catalytic properties in terms of high catalytic activity, exclusion of undesirable side-reactions such as racemization, and operations under mild conditions. The most specific features of enzyme function are the high substrate specificity including regioselectivity and stereospecificity. As a consequence, enzymes have been used in various industrial and medical fields. Bioconjugation has expanded the possibility of application of enzymes towards bioreactor catalyst, bioreactor sensor and medical drug technologies. Immobilization of enzymes onto solid matrices has enabled the recyclization of enzymes: immobilization of enzymes onto sensing devices including electrodes and optodes has also provided the basis for biochemical sensors. Bioconjugation of medical enzymes extracted from animals with an amphiphilic polymer, polyethylene glycol, has been shown to reduce the immuno-reaction induced by the application of sensor or therapeutic enzymes into the human body. Various bioconjugations of biological molecules are very important in the biomedical fields (Aslam and Dent, 1998). Bioconjugation is divided into two categories in the present review. One is geneengineered bioconjugation, and the other chemically engineered bioconjugation (Figure 10.1). Gene-engineered modification has been used for the alteration of enzymatic activity, such as thermal stabilization (Bryan et al., 1986), alteration of