Chemical Synthesis of Native-Type Cellulose and Its Analogues via Enzymatic Polymerization |
| |
Authors: | Shiro Kobayashi Etsuya Okamoto Xin Wen Shin-Ichiro Shoda |
| |
Affiliation: | Department of Molecular Chemistry and Engineering Faculty of Engineering , Tohoku University , Sendai, 980-77, Japan |
| |
Abstract: | Abstract The first successful chemical synthesis of cellulose was achieved by a polycondensation of β-cellobiosyl fluoride monomer catalyzed with cellulase, an extracellular hydrolytic enzyme of cellulose, in a mixed solvent of acetonitrile and acetate buffer. The product, synthetic cellulose, was the crystalline allomorph cellulose II, a thermodynamically more stable form. More detailed examinations of the polymerization conditions led to the formation of the native cellulose I, a metastable allomorph, for the first time. The key to the success was to use partially purified cellulase and an appropriate mixed solvent of acetonitrile/buffer. The formation of the two allomorphs of cellulose implies that the polarity of the glucan chain ordering can be controlled in a test tube. Based on these findings, a new concept “choroselectivity,” meaning spacial control in ordering the macromolecular chain, has been proposed. Cellulose analogues, 6-O-methylated cellulose and xylan, have been synthesized regio- and stereoselectively by using the enzymatic polymerization technique. |
| |
Keywords: | |
|
|