Cellulose is the most abundant macromolecule on earth. As such. it has ignited a tremendous impact upon so many human activities. The anomaly of this impact is that while so much is known about the utilization of cellulose, relatively little is fully understood about the structure and biosynthesis of the native allomorph. Yet, progress is being made. Recently, we have achieved the perfection of extended glucan chain polymerization and crystallization into the metastable allomorph, cellulose I using two different assembly pathways. The first involves an in vitro assembly with the natural substrate, UDP-glucose and a digitonin-solubilized, product-entrapped enzyme fraction from the plasma membrane. The second entails the use of a highly purified cellulase as the catalyst and ß-cellobiosyl fluoride as the substrate in an acetonitrile/aqueous buffer medium. Although these two reaction pathways are very different, they yield the cellulose I allomorph. A third pathway to cellulose I assembly has been more indirect using the living cell, Acetobacter xylinum. Photoisomerization of a dye-altered glucan sheet results in the in vivo assembly cellulose I. Molecular modeling with MM3 energy minimization has yielded new data on the sequence of events of crystallization. This presentation will cover these recent advances in our knowledge of cellulose polymerization/crystallization. From these new data have emerged new concepts and strategies to consider in the fabrication of natural polymer systems with superior strength and valuable new properties.
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