| Enzyme Specificity | - This enzyme releases nonreducing terminal ß(1-2,3,4, and 6)-linked N-acetylglucosamine from complex carbohydrates. When incubated with oligosaccharides at low concentrations (less than 50 mU/ml) the enzyme can differentiate between GlcNAcß1-2Man, GlcNAcß1-4Man and GlcNAcß1-6Man linkages. Under such conditions, the enzyme cleaves only ß1-2 linked GlcNAc, with two provisos. First, ß1-2 GlcNAc is not hydrolyzed if the mannose to which it is substituted has a substitution at C-6. Thus, the enzyme is useful for the analysis of triantennary oligosaccharides. Second, if the ß-linked mannose of the conserved pentasaccharide core is substituted with a ‘bisecting’ GlcNAc then only the ß1-2 linked GlcNAc linked to mannose on the a1-3 arm is cleaved. At higher concentrations of the enzyme, ß(1-4) and ß(1-6)-linked GlcNAc may also be hydrolyzed. The reported activity against O-linked oligosaccharides suggests that GlcNAc ß1-3Gal and GlcNAc ß1-6Gal are digested1. Although the specificity towards oligosaccharides containing GalNAc is not known, the enzyme, in common with other glucosaminidases, also hydrolyses pNP-ß-GalNAc at pH 6.0 and 37C. The activity towards this substrate is ~7 fold less than towards pNP-ßGlcNAc.
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