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KMID : 0545119980080060568
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Journal of Microbiology and Biotechnology
1998 Volume.8 No. 6 p.568 ~ p.574
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Purification and Characteristics of Two Types Types of Chitosanases from Aspergillus fumigatus KH-94
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Kim, Soon Young
Shon, Dong Hwa/Lee, Ke Ho
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Abstract
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Two types of chitosanases produced from Aspergillus fumigatus KH-94 were purified by ion exchange and gel permeation chromatography. Molecular weights of the enzymes are 22.5 kDa (chitosanase Ⅰ) and 108 kDa (chitosanase Ⅱ). pI, optimum pH, and temperature of chitosanase I are 7.3, 5.5, and 70∼80℃, respectively, and those of chitosanase Ⅱ are 4.8, 4.5∼5.5, and 50∼60℃, respectively. Activities of both chitosanases were increased by Mn^2+ but inhibited by Cu^2+ and Hg^2+. Chitosanase Ⅰ has endosplitting activity that hydrolyzes chitopentaose, chitohexaose, and chitosan to chitobiose, chitotriose, and chitotetraose, whereas chitosanase Ⅱ has exo-splitting activity that hydrolyzes chitobiose and chitosan to glucosamine. Chitosanase Ⅱ was found to have transglycosylation activity also in the reaction of 2% more chitooligosaccharides as a substrate and at the initial reaction. The higher degree of deacetylation, the stronger activities of chitosanase I and Ⅱ toward chitosans. Both chitosanases could hydrolyze chitosan and glycol chitosan but not chitin, cellulose, and carboxymethyl cellulose. To produce higher degree of polymerization of chitooligosaccharides, chitosanase I was used and yielded 80% of recovery.
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