PURIFICATION AND CHARACTERIZATION OF AN ENDO-N-ACETYL-BETA-D-GLUCOSAMINIDASE FROM THE CULTURE-MEDIUM OF STIGMATELLA-AURANTIACA DW4

A novel endo-N-acetyl-beta-D-glucosaminidase (ENGase), acting on the d i-N-acetylchitobiosyl part of N-linked glycans, was characterized in t he culture medium of Stigmatella aurantiaca DW4. Purified to homogenei ty by ammonium sulfate precipitation, gel filtration, and chromatofocu sing, this ENGase presents, upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis, a molecular mass near 27 kDa. Optimal pH and pI were 4.0 and 6.8, respectively. The enzyme, named ENGase St, exhibits high activity on oligomannoside-type glycoasparagines and glycoprotein s and could also hydrolyze hybrid- and complex-type glycoasparagines b ut does not acts as a murein hydrolase.