Novel Reaction Route Including Enzymic Reaction For A Synthesis Of A Branched Polysaccharide |
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| Authors: | Kenichi Hatanaka Soo-Chang Song Atsushi Maruyama Toshihiro Akaike Akira Kobayashi Hiroyoshi Kuzuhara |
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| Institution: | 1. Department of Biomolecular Engineering, Tokyo Institute of Technology, Nagatsuta, Midori-ku, Yokohama 227, Japan;2. Kanagawa Academy of Science and Technology, Sakado, Takatsu-ku, Kawasaki-shi, Kanagawa 213, Japan;3. RIKEN (The Institute of Physical and Chemical Research), Hirosawa, Wako-shi, Saitama 351, Japan |
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| Abstract: | AbstractStereoselective synthesis of α-D-glucosyl-branching polysaccharide by chemical and enzymic reactions was investigated. Ring-opening polymerization of 1,6-anhydro-3-O-benzoyl-2,4-di-O-benzyl-β-D-glucopyranose (1) with PF5 as catalyst at low temperature gave a highly stereoregular polymer, which was converted to 2,4-diO-benzyl-(1→6)-α-D-glucopyranan by debenzoylation with sodium methoxide. The polymer was glucosylated according to the glycosyl imidate method. Deprotection of the branched polysaccharide was carried out with sodium in liquid ammonia at -78 °C to give a (1→6)-α-D-glucopyranan having α-D-glucopyranosyl and β-D-glucopyranosyl branches. Only the β-D-glucopyranosyl branch of the polymer was completely removed by enzymatic hydrolysis by the use of cellulase to provide stereoregular (1→6)-α-D-glucopyranan having an α-D-glucopyranosyl branch at the C-3 position. Polymers were characterized by optical rotation, NMR spectroscopy, GPC, and X-ray diffractometry. |
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