An endochitinase from centrifuged autolyzed cultures of Aspergillus nidulans has been purified 100 times. The enzyme has Mw 27,000, pI of 4.8 units, pH optimum around 5 pH units. It is unstable at temperature greater than 70 degrees C and does not have a cation requirement. It is inhibited by Hg2+, Cu2+, Ca2+ and Ag+ and it does not have muramidase activity. The enzyme depolymerizes chitin rapidly with production of high molecular weight polysaccharides, and then slowly degrades these with production of N,N'-diacetylchitobiose. The enzyme hydrolyzes N,N',N''-triacetylchitotriose with production of N,N'-diacetylchitobiose and N-acetylglucosamine and this hydrolysis is inhibited by other chitin oligomers and N-acetylglucosamine. This enzyme hydrolyzes in the same way the chitin obtained from the cell wall of Aspergillus nidulans.
An endochitinase from centrifuged autolyzed cultures of Aspergillus nidulans has been purified 100 times. The enzyme has Mw 27 000, pI of 4.8 units, pH optimum around 5 pH units. It is unstable at temperature > 70°C and does not have a cation requirement. It is inhibited by Hg2+, Cu2+, Ca2+ and Ag+ and it does not have muramidase activity. The enzyme depolymerizes chitin rapidly with production of high molecular weight polysaccharides, and then slowly degrades these with production of N,N′‐diacetylchitobiose. The enzyme hydrolyzes N,N′,N″‐triacetylchitotriose with production of N,N′‐diacetylchitobiose and N‐acetylglucosamine and this hydrolysis is inhibited by other chitin oligomers and N‐acetylglucosamine. This enzyme hydrolyzes in the same way the chitin obtained from the cell wall of Aspergillus nidulans.
A hexosaminidase from autolyzed cultures of Aspergillus nidulans was purified 196 fold and characterized as a β‐N‐acetylglucosaminidase (EC 3.2.1.30). The enzyme has a MW of 190 000, a pI of 4.3, and optimum pH of 5.0 and is unstable at temperatures above 50°C. The enzyme is a glyco‐protein with 19.5% sugars, mannose being the principal component. It binds strongly to chitin. The enzyme hydrolyzes different substrates. The Ki with the competitive inhibitor 2‐acetamido‐2‐deoxy‐d‐gluconolactone was independent of the substrate used. The enzyme was inhibited by Hg2+, Ag+, acetate and other organic anions. The kinetics of hydrolysis of chitin oligosaccharides from 2 to 6 units was studied by HPLC. This enzyme is an exoenzyme which degraded chitin oligomers gradually with the production of N‐acetylglucosamine. The hydrolysis of N‐N′‐diacetylchito‐biose was inhibited non‐competitively by glucosamine and N‐acetylglucosamine. In mixtures of chitin oligosaccharides, the hydrolysis of chitobiose was competitively inhibited by each of the other oligomers.
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