DENATURATION OF NATIVE AND DEGLYCOSYLATED α-GALACTOSIDASES FROM Penicillium canescens BY GUANIDINE HYDROCHLORIDE

Abstract

The aim of this work was the study of native and deglycosylated -galactosidases from Penicillium canescens under denaturing conditions caused by guanidine hydrochloride. Calculation of kinetics and constants of enzymes inactivation was carried out on using experimental kinetic curves of enzyme denaturation. We observed significant differences in the kinetics of inactivation of native and deglycosylated -galactosidases from P. canescens caused by guanidine hydrochloride. Native enzyme was stable within the selected range of guanidine hydrochloride concentrations (from 0.1 to 3.0 M), retaining no less than 50% of the initial enzyme activity for 3 days. Deglycosylated enzyme preparations were less stable and they lost their activity within 5–30 minutes, when they were treated with guanidine hydrochloride in concentrations above 1 M. Dissociation rate constant of native and deglycosylated forms of the enzyme differed by 10 to 100 folds. It was shown that subunit interactions play a major role in the process of inactivation of the enzyme, and the carbohydrate component is essential for stabilizing of subunit bonds and maintaining conformational stability of the enzyme under denaturing conditions of chemical agents.