Synthesis of Cellulose and Its Formation Mechanism

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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.