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A purified ovalbumin glycopeptide, Asn-(GlcNAc)₂(Man)₅ was [¹⁴C]acetylated in the asparagine moiety. Using the [¹⁴C]acetylated glycopeptide as a substrate, an endo-β-N-acetylglucosaminidase was purified 2400-fold from the culture fluid of Diplococcus pneumoniae. The enzyme preparation was practically free from various exoglycosidases and proteases. The enzyme cleaved the di-N-acetylchitobiose structure of the [¹⁴C]acetylated glycopeptide, yielding equimolar amounts of [¹⁴C]acetyl-Asn-GlcNAc and (Man)₅(GlcNAc). The enzyme had a pH optimum of 6.5, with a K_m of 0.25 mm and with a V_max of 4.67 µmoles per mg of protein per min toward the substrate.

A mouse myeloma IgG glycopeptide and a bovine IgG glycopeptide was hydrolyzed by the enzyme, only after treatment with β-galactosidase and β-N-acetylglucosaminidase. In both cases the products of the enzymic action were a fucose-containing …