THE SELF CATALYTIC ENZYME INACTIVATION INDUCED BY SOLVENT STIRRING - A NEW EXAMPLE OF PROTEIN CONFORMATIONAL CHANGE INDUCTION

This article gives a new example of the protein conformational change induction, A well known example widely described in the literature is the prion, a protein whose the pathologic form, PrPsc, induces a confo rmational change of the normal form, PrPc, by interaction with it, Thi s work highlights the existence of a self-catalytic conformation chang e for lysozyme, The functional modification of this protein is analyse d in terms of irreversible loss of activity, Our experiments and the k inetic model derived from our results show that lysozyme inactivation is catalyzed by the inactivated lysozyme molecules; the lysozyme molec ules with modified conformation induce a conformational change of nati ve lysozyme molecules that in turn become inactive, This phenomenon is enhanced by stirring, which increases the probability and the efficie ncy of collisions between enzyme molecules, Furthermore, the self-cata lytic inactivation kinetics of lysozyme is increased when salts are di ssolved in the enzyme solution, Under these conditions, the protective effect due to the addition of salts, reported in previous literature, disappear, Salt-induced lysozyme destabilization effect can be observ ed, The salts enhance the aggregation of inactive enzyme molecules, A kinetic model of self catalytic inactivation of the enzyme has been de veloped, taking into account the results obtained with and without the addition of salts in aqueous solution.