tailieunhanh - Báo cáo khoa học: Activation of crystalline cellulose to cellulose IIII results in efficient hydrolysis by cellobiohydrolase

The crystalline polymorphic form of cellulose (cellulose Ia-rich) of the green alga,Cladophora, was converted into cellulose III I and Ib by super-critical ammonium and hydrothermal treatments, respectively, and the hydrolytic rate and the adsorption of Trichoderma viridecellobiohydro-lase I (Cel7A) on these products were evaluated by a novel analysis based on the surface density of the enzyme. | ỊFEBS Journal Activation of crystalline cellulose to cellulose IIII results in efficient hydrolysis by cellobiohydrolase Kiyohiko Igarashi Masahisa Wada and Masahiro Samejima Department of Biomaterials Sciences Graduate Schoolof Agriculturaland Life Sciences University of Tokyo Japan Keywords ammonia cellulose cellobiohydrolase cellobiose dehydrogenase crystalline polymorphs solid-liquid interface Correspondence M. Samejima Department of Biomaterials Sciences Graduate School of Agricultural and Life Sciences University of Tokyo 1-1-1 Yayoi Bunkyo-ku Tokyo 113-8657 Japan Fax 81 3 5841 5273 Tel 81 3 5841 5255 E-mail amsam@ Received 10 January 2007 revised 31 January 2007 accepted 2 February 2007 doi The crystalline polymorphic form of cellulose cellulose Ia-rich of the green alga Cladophora was converted into cellulose IIII and Ip by supercritical ammonium and hydrothermal treatments respectively and the hydrolytic rate and the adsorption of Trichoderma viride cellobiohydro-lase I Cel7A on these products were evaluated by a novel analysis based on the surface density of the enzyme. Cellobiose production from cellulose IIII was more than 5 times higher than that from cellulose I. However the amount of enzyme adsorbed on cellulose IIII was less than twice that on cellulose I and the specific activity of the adsorbed enzyme for cellulose IIIl was more than 3 times higher than that for cellulose I. When cellulose IIIl was converted into cellulose Ip by hydrothermal treatment cellobiose production was dramatically decreased although no significant change was observed in enzyme adsorption. This clearly indicates that the enhanced hydrolysis of cellulose IIII is related to the structure of the crystalline polymorph. Thus supercritical ammonium treatment activates crystalline cellulose for hydrolysis by cellobiohydrolase. Cellulose is a linear polymer of p-1 4-linked anhydrous glucose residues and is the major component

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