| Budget Amount *help |
¥2,530,000 (Direct Cost: ¥2,200,000、Indirect Cost: ¥330,000)
Fiscal Year 2007: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Fiscal Year 2006: ¥1,100,000 (Direct Cost: ¥1,100,000)
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| Research Abstract |
Chitosan oligosaccharides consist of between 2 and 10 glucosamine units that are bound via beta-1, 4-glycoside linkages. Their higher oligosaccharides (pentamer or larger oligomers) possess various physiological activities such as antimicrobial, antitumor and immunoenhancing activities. Therefore, in order to utilize chitosan oligosaccharides as functional food materials and pharmaceuticals, products containing a large fraction of higher oligosaccharides are desirable. Chitosan oligosaccharides can be obtained from the partial hydrolysis of chitosan. As the higher oligosaccharides such as pentamers and hexamers are intermediate products in chitosan hydrolysis, it is necessary to control the hydrolysis reaction to produce them at high yield. The use of enzymes in an immobilized form would be effective at obtaining higher oligosaccharides for the following reasons: 1. As enzymes immobilized on insoluble materials can be separated immediately from the reaction mixture, hydrolysis reactions can be terminated easily before the yield of target higher oligosaccharides becomes lower due to further degradation; 2. The reaction can be stopped without any chemicals or heating; and 3. Enzyme catalysts can be recovered and used repeatedly. By considering these points, we studied the immobilization of chitosanase and presented a method for obtaining stable immobilized chitosanase on amylose-coated magnetic nanoparticles using the multipoint-attachment method, and then utilized the immobilized enzyme to produce chitosan oligosaccharides. The immobilized chitosanase was used to produce pentamers and hexamers of chitosan oligosaccharides, which possess beneficial biological activities. In batch hydrolysis of chitosan using the immobilized chitosanase, a high yield of target oligosaccharides (40% of the used chitosan, based on weight) was successfully obtained. The immobilized chitosanase could be recovered and reused repeatedly.
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