DENATURATION OF URIDINE PHOSPHORYLASE FROM ESCHERICHIA-COLI K-12 BY GUANIDINE-HYDROCHLORIDE

Denaturation of uridine phosphorylase from Escherichia coli K-12 by gu anidine hydrochloride results in red shift of the maximum in the prote in fluorescence spectrum, dissociation of the hexameric enzyme molecul e into monomers, and the loss of the enzymatic activity. The initial r ate of the enzyme reactivation after the dilution of the enzyme preinc ubated with guanidine hydrochloride has the second order with respect to protein. It is assumed that the rate of the reactivation process is limited by the reassociation of monomers possessing low enzymatic act ivity to dimers followed by the rapid step of hexamer formation.