A NOVEL FUNGAL ENDO-BETA-N-ACETYLGLUCOSAMINIDASE THAT SPECIFICALLY ACTS ON PLANT GLYCOPROTEINS

An endo-beta-N-acetylglucosaminidase specific for plant glycoprotein o ligosaccharides was purified from the culture fluid of a fungus. The M r of the purified enzyme was 89,000. This enzyme was stable at pH 5.5- 7.0, up to 30 degrees C, and showed the highest activity at pH 6.0. Am ong sugar chains tested, xylose-containing sugar chains (M3X, M3FX, an d M2FX) were the most favored substrates. Oligomannose type (M3, M5, a nd M9) and hybrid type (GNM3) sugar chains were hydrolyzed much more s lowly than xylose-containing sugar chains, and a complex type sugar ch ain (GN2M3) was not hydrolyzed at all by the enzyme. Moreover, the enz yme released sugar chains from native horseradish peroxidase and stem bromelain, which were not hydrolyzed by other endo-beta-N-acetylglucos aminidases (Endo H, D, and F). The enzyme could transfer the xylose-co ntaining sugar chain from bromelain to DNS-Asn-GlcNAc-Fuc.