Stabilization and Immobilization of Enzymes with Imidoesters

Abstract

Two major drawbacks to the use of enzymes are 1) the operational limitations associated with a soluble catalyst, which include mechanical loss, non-reusability, product contamination and limited reactor design, and 2) the loss of activity. The first of these problems has received considerable attention and can be circumvented by immobilization, with a wide variety of techniques, both physical and chemical in nature, having been proposed (1). On the contrary, not much work has been done toward circumventing the second problem of enzymic inactivation. Loss of activity in enzymes can be caused by metal ion inhibition, chemical modifications such as bond cleavage, or by denaturation. Denaturation is probably the most common form of inactivation and is defined as a process, or sequence of processes, in which the spatial arrangement of the polypeptide chains within the molecule is changed from that typical of the native protein to a more disordered arrangement (2). It is a complex process which can be either reversible or irreversible depending on the conditions of pH, concentration, ionic strength, temperature, etc. Denaturation can be caused by excessive heat or by a high concentration of urea, guanidine hydrochloride, organic solvents, hydroxyl or hydronium ions.