Purification and characterization of beta-N-acetylhexosaminidase from Trichoderma harzianum

beta-N-Acetylhexosaminidase was produced by Trichoderma harzianum cultivated with chitin as the growth substrate. The enzyme was purified 13.2-fold to homogeneity by ultrafiltration and sequential chromatography on SP-Toyopearl and Sephacryl S-200. The molecular weight of the enzyme was estimated to be about 150,000 by gel filtration. The pH and temperature optima were 4.0-5.5 and 50 degrees C, respectively. The enzyme hydrolyzed N-acetylchitooligosaccharides at the non-reducing ends to release GlcNAc monomer. The enzyme showed a strict substrate specificity to the sugar chains in complex carbohydrates, hydrolyzing only the linkage of GlcNAc beta 1-3Gal, but not hydrolyzing the other linkages such as GalNAc beta 1-3Gal and GlcNAc beta 1-2Man.