Heterogeneity of exo-type of beta-N-acetylglucosaminidase in human parotid saliva

The exo-type of β-N-acetylglucosaminidase (NAGase) in human parotid saliva was separated into two fractions, NAGase A and B, by diethylaminoethanol (DEAE)-cellulose column chromatography. The heterogeneity was confirmed by isoelectric focusing and disc electrophoresis. Isoelectric points of NAGase A and B were at pH 7.2 and 5.0, respectively. NAGase A was more heat-stable than NAGase B. A slight difference in pH optimum was found between NAGase A and B. Both components had almost the same Km values for p-nitrophenyl N-acetylβ-glucosaminide, p-nitrophenyl N-acetyl-β-galactosaminide, phenyl N-acetyl-β-glucosaminide and phenyl N-acetyl-β-galactosaminide.