INACTIVATION OF A SUBTILISIN IN COLLOIDAL SYSTEMS

The aim of the present study is to establish the relation between the inactivation of the proteolytic enzyme Savinase(TM) and its adsorption at different types of solid-liquid interfaces. The loss of activity h as been determined both in solution and in the presence of colloidal p articles, which provide a surface area for adsorption of 25% of the en zyme population. Analysis of the remaining solution at different perio ds of incubation of the various systems shows that the intact protein is converted into autolytic degradation products at the expense of bio logical activity. The different particles, however, deactivate the enz ymes to a different extent. Under the experimental conditions the half -life of the enzymatic activity in solution is 3.5 hours. In the prese nce of particles that have hydrophobic surface properties (teflon- or polystyrene latex) the half-life is reduced to 0.7 hours. On the contr ary, hydrophilic silica particles stabilize the enzyme against autolys is as compared to the inactivation in solution. Polystyrene latex part icles which are chemically grafted with short poly(ethylene oxide) cha ins ([EO](g)) are, for steric reasons, also mild with respect to the r eduction of enzymatic stability. It is thus concluded that the type of surface determines the mode in which the enzyme is adsorbed on a part icle which, in turn, affects the autocatalytic rate.