Einwirkung von Chlorwasserstoff auf Glucose. Synthese eines Polyglucosans

Proceedings of the Japan Academy. Ser. B: Physical and Biologic

2007

This review focuses on the in vitro synthesis of polysaccharides, the method of which is ''enzymatic polymerization'' mainly developed by our group. Polysaccharides are formed by repeated glycosylation reactions between a glycosyl donor and a glycosyl acceptor. A hydrolysis enzyme was found very efficient as catalyst, where the monomer is designed based on the new concept of a ''transition-state analogue substrate'' (TSAS); sugar fluoride monomers for polycondensation and sugar oxazoline monomers for ring-opening polyaddition. Enzymatic polymerization enabled the first in vitro synthesis of natural polysaccharides such as cellulose, xylan, chitin, hyaluronan and chondroitin, and also of unnatural polysaccharides such as a cellulose-chitin hybrid, a hyaluronan-chondroitin hybrid, and others. Supercatalysis of hyaluronidase was disclosed as unusual enzymatic multi-catalyst functions. Mutant enzymes were very useful for synthetic and mechanistic studies. In situ observations of enzymatic polymerization by SEM, TEM, and combined SAS methods revealed mechanisms of the polymerization and of the self-assembling of high-order molecular structure formed by elongating polysaccharide molecules.

Section: )mentioning

confidence: 99%

New developments of polysaccharide synthesis via enzymatic polymerization

Proceedings of the Japan Academy. Ser. B: Physical and Biologic

2007

“…A strong reason was that in the history of polymer science, cellulose had been an important target molecule for Staudinger, Mark, and other prominent scientists with respect to its structure, molecular weight, and derivatization reactions since the 1920s, and so cellulose had a very symbolic existence for polymer scientists. 24 This was the strongest motivation for me, even though, since a first attempt at chemical cellulose synthesis in 1941, 25 no successful synthesis had been reported.…”

Section: Cellulose Synthesismentioning

confidence: 99%

Challenge of synthetic cellulose

J. Polym. Sci. A Polym. Chem.

2004

This article focuses on why and how the chemical synthesis of cellulose was accomplished. The synthesis of cellulose was an important, challenging problem for half a century in polymer chemistry. For the synthesis, a new method of enzymatic polymerization was developed. A monomer of β‐D‐cellobiosyl fluoride (β‐CF) was designed and subjected to cellulase catalysis, which led to synthetic cellulose for the first time. Cellulase is a hydrolysis enzyme of cellulose; cellulase, inherently catalyzing the bond cleavage of cellulose in vivo, catalyzes the bond formation via the polycondensation of β‐CF in vitro. It is thought that the polymerization and hydrolysis involve a common intermediate (transition state). This view led us to a new concept, a transition‐state analogue substrate, for the design of the monomer. The preparation of cellulase proteins with biotechnology revealed the enzymatic catalytic functions in the hydrolysis and polymerization to cellulose. High‐order molecular structures were in situ formed and observed as fibrils (cellulose I) and spherulites (cellulose II). In situ small‐angle neutron scattering measurements suggested a fractal surface formation of a synthetic cellulose assembly. The principle of cellulose synthesis was extended to the synthesis of other natural polysaccharides, such as xylan and amylose, and unnatural polysaccharides. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 693–710, 2005

“…[11] Twenty years later, such investigations became very intense. Synthesis of polysaccharides from respective monosaccharides, such as D-glucose, D-mannose, D-galoctose and Dxylose, was attempted by proton-catalyzed dehydration polymerization in dimethyl sulfoxide (DMSO).…”

Section: Synthesismentioning

confidence: 99%

“…The first attempt to synthesize polysaccharides may be credited to a study of German chemists in 1941 11. Twenty years later, such investigations became very intense.…”

Section: Polysaccharidesmentioning

confidence: 99%

Biomacromolecules and Bio‐Related Macromolecules

Macro Chemistry & Physics

Uyama

2003

The present article briefly reviews research developments in the area of biomacromolecules and bio‐related macromolecules, whose research papers have been published for several decades preferably in the Macromolecular Journals. The area covers the important classes of macromolecules, polysaccharides (cellulose, amylose, chitin, etc.), polyesters (poly(lactic acid), poly(hydroxyalkanoate)s, etc.), and phenolic polymers (lignin, urushi, etc.). These polymers and their derivatives are very important for scientific interests as well as for industrial applications. Their synthesis, structure, reactions, and properties are mainly mentioned, and important topics of the target polymers are selected and mostly chronologically reviewed.