title: Characterization of a chitosanase from Aspergillus fumigatus ATCC13073.
abstract: Chitosanase II was purified from the culture filtrate of Aspergillus fumigatus ATCC13073. The purified enzyme had a molecular mass of 23.5 kDa. The N-terminal amino acid sequence of chitosanase II was identical to those of other Aspergillus chitosanases belonging to glycoside hydrolase family 75. The optimum pH and temperature were pH 6.0 and 40 °C. Chitosanase II hydrolyzed 70% deacetylated chitosan faster than fully deacetylated chitosan. Analysis of the degradation products generated from partially N-acetylated chitosan showed that chitosanase II split GlcN-GlcN and GlcNAc-GlcN bonds but not GlcNAc-GlcNAc or GlcN-GlcNAc, suggesting that it is a subclass I chitosanase. It degraded (GlcN)(6) to produce (GlcN)(3) as main product and small amounts of (GlcN)(2) and (GlcN)(4). Reaction rate analyses of mono-N-acetylated chitohexaose suggested that the (+3) site of chitosanase II recognizes the GlcNAc residue rather than the GlcN residue of its substrate.
authors.affiliation: Department of Applied Biochemistry and Food Science, Saga University, 1-Honjo, Saga 840-8502, Japan.
authors.forename: Katsuaki
authors.initials: K
authors.lastname: Hirano
authors.forename: Sitthinan
authors.initials: S
authors.lastname: Arayaveerasid
authors.forename: Kiyohiko
authors.initials: K
authors.lastname: Seki
authors.forename: David J
authors.initials: DJ
authors.lastname: Adams
authors.forename: Masaru
authors.initials: M
authors.lastname: Mitsutomi
mesh_terms: D000107:Acetylation; D001232:Aspergillus fumigatus / Q000737:chemistry / Q000201:enzymology*; D048271:Chitosan / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D002852:Chromatography, Ion Exchange; D003470:Culture Media; D005656:Fungal Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D006026:Glycoside Hydrolases / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D009844:Oligosaccharides / Q000378:metabolism*; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D003470:Culture Media; D005656:Fungal Proteins; D009844:Oligosaccharides; C050523:chitohexaose; D048271:Chitosan; D006026:Glycoside Hydrolases; C019868:chitosanase