Purification and Properties of an Endo-β-N-acetylglucosaminidase from Streptomyces griseus

TLDR

The endo‑β‑N‑acetylglucosaminidase was purified to homogeneity from Streptomyces griseus filtrates, separated by Sephadex G‑100 chromatography, and assayed with [3H]dansyl‑Asn derivatives and other oligosaccharide substrates. The purified enzyme has a molecular weight of 27,200 Da, is a single polypeptide chain, remains stable at 37 °C for at least 48 h, resists proteolytic inactivation, hydrolyzes various di‑N‑acetyl‑glucosamine‑containing oligosaccharides to specific products, and does not act on Asn‑(GlcNAc)₂(Man)₁, which is cleaved by a distinct endo‑β‑acetylglucosaminidase.

Abstract

Abstract An enzyme that hydrolyzes di-N-acetylchitobiose linkages in oligosaccharides and glycoproteins was purified to homogeneity from cultural filtrates of Streptomyces griseus. The molecular weight of the enzyme, determined by sedimentation equilibrium analysis, is 27,200 ± 200, and it appears to consist of a single polypeptide chain. This apparent endo-β-N-acetylglucosaminidase was completely stable at 37° for at least 48 hours and resistant to inactivation by several proteolytic enzymes. Treatment of Asn-(GlcNAc)2(Man)6, Asn-(GlcNAc)2(Man)6(GlcNAc)2, and (GlcNAc)2(Man)6(Glc-NAc)2 with the enzyme yielded Asn-GlcNAc + (GlcNAc)1-(Man)6, Asn-GlcNAc + (GlcNAc)1(Man)6(GlcNAc)2, and GlcNAc + (GlcNAc)1(Man)6(GlcNAc)2, respectively. The [3H]dansyl-Asn derivatives, which were rapidly hydrolyzed also, were used as substrates to assay the enzyme. Similar findings obtained with specific glycoproteins are described in the accompanying paper (Tarentino, A. L., Plummer, T. H., and Maley, F. J., Jr., and Maley, F. (1974) J. Biol. Chem. 249, 818–824). Asn-(GlcNAc)2(Man)1 was not hydrolyzed by this enzyme but was hydrolyzed by another apparent endo-β-N-acetyl-glucosaminidase. The latter could be separated from the Asn-(GlcNAc)2(Man)6 hydrolyzing endoglycosidase by Sephadex G-100 chromatography.