Reactivation of heterodimer and individual subunits of penicillin acylase from E-coli after inactivation in urea

Individual subunits of penicillin acylase from E. coli were isolated by gel -filtration under denaturing conditions (8 M urea). Recovery of the catalyt ic activity of the penicillin acylase heterodimer was studied after removal of urea. in the case of the heterodimer, 40-60% of the initial activity wa s recovered, whereas the activity of individual subunits was not recovered. Combination of native enzyme subunits with subunits isolated from the enzy me pre-inactivated with the irreversible inhibitor phenylmethyisulfonyl flu oride resulted in heterodimers which were active only in the case of involv e ment of the beta-subunit of the active enzyme.