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Synthesis of Cellulose and Its Formation Mechanism

纤维素的合成及其形成机理

基本信息

批准号：
04044021
负责人：
KOBAYASHI Shiro
金额：
$ 5.7万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for international Scientific Research
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1993
项目状态：
已结题

项目摘要

Direct Visualization of Synthetic Cellulose Formation by Transmission Electron MicroscopyThe process of synthetic cellulose formation in an acetonitrile-buffer solvent system by enzymatic polymerization of beta-cellobiosyl fluoride monomer using cellulase as catalyst was visualized by transmission electron microscopy. Synthetic cellulose could be observed as soon as 30 sec after initiation of the polymerization. A micellar phase separation occurred at the initial stage of the reaction. Irregular aggregates of cellulose were formed at the boundary of the micellar particle, suggesting that the interface is the site of polymerization. The cellulose product after treatment with hot surfactant solution was strongly labeled with cellobiohydrolase-gold particles, indicating that the produced polymer is cellulose. The electron diffraction pattern of the product showed the typical pattern of crystal structure of cellulose II.The First In Vitro Synthesis of Cellulose ICellullose microfibrils with an electron diffraction pattern characteristic of native cellulose I have been synthesized abiotically via a cellulase-catalyzed polymerization of beta-cellobiosyl fluoride substrate monomer in an optimized acetonitrile/acetate buffer system. Partial purification of the Trichoderma viride cellulase enzyme was found essential for the formation of the synthetic cellulose I allomorph. Assembly of synthetic cellulose I appears to be a result of a micellar aggregation of the partially purified enzyme and the substrate in an organic/aqueous solvent system, favoring the alignment of glucan chains with the same polarity and extended chain conformation resulting in the crystallization to form the metastable cellulose I allomorph.

合成纤维素形成的透射电子显微镜直接观察在乙腈-缓冲溶剂体系中，通过使用纤维素酶作为催化剂的β-纤维二糖基氟单体的酶促聚合，合成纤维素形成的过程通过透射电子显微镜观察。在聚合反应开始后30秒即可观察到合成纤维素。在反应的初始阶段发生胶束相分离。纤维素的不规则聚集体在胶束颗粒的边界处形成，表明界面是聚合的位点。用热表面活性剂溶液处理后的纤维素产物用纤维二糖水解酶-金颗粒强烈标记，表明所产生的聚合物是纤维素。该产品的电子衍射图案显示了纤维素II的晶体结构的典型图案。纤维素的首次体外合成具有天然纤维素I的电子衍射图案特征的ICcellulose微纤丝已经通过纤维素酶催化的β-纤维二糖基氟底物单体在优化的乙腈/乙酸盐缓冲体系中的聚合而非生物合成。绿色木霉纤维素酶的部分纯化被发现是合成纤维素I异形体的形成所必需的。合成纤维素I的组装似乎是部分纯化的酶和底物在有机/水性溶剂系统中的胶束聚集的结果，有利于具有相同极性和延伸链构象的葡聚糖链的排列，导致结晶形成亚稳态纤维素I异形体。