ABSTRACT
Immobilization of an enzyme confines or localizes it to an inert, insoluble material so that it can be reused continuously and its stability is greatly increased. Although an immobilized enzyme is held in a solid matrix throughout the reaction, the product can be easily separated from the matrix. An immobilized enzyme may be reused until and unless the activity of the enzyme decreases drastically. Soluble enzymes may be immobilized by an ultrafiltration membrane. The selection of an immobilization technique for a particular enzyme depends on the desirable characteristics of certain parameters such as preparation, cost, and binding force. The characteristics of immobilized enzymes play an important role for the operation of the process. The activities of immobilized enzymes are generally expressed in international units, defined as micromoles of substrate converted per minute per gram of immobilized enzyme. The difference between the specific activity of immobilized enzymes and that of the soluble enzyme indicates the effectiveness of the immobilization procedure.
