Hybrid polysaccharides cellulose-chitin

Scheme 8 Enzymatic polymerizations to a cellulose-chitin hybrid polysaccharide.

Kobayashi et have also investigated other modes of enzymatic polymerization to produce a novel cellulose-chitin hybrid polysaccharide. A sugar fluoride monomer of GlcNAc/3(l 4)Glc (17) was designed as a TSAS monomer for polymerization catalyzed by cellulase from Trichoderma viride. In the polymerization, monomer 17 was recognized by cellulase from T. viride, leading to a cellulose-chitin hybrid polysaccharide 18 with perfect regioselectivity and stereochemistry (Scheme 17). 

After completion of the enzymatic reaction, a white precipitate was separated by centrifugation, and the supernatant was analyzed by MALDI-TOF/MS, and NMR measurements. From the MALDI-TOF/MS spectrum, the peaks appeared at every m z 365, corresponded to the molecular mass of the repeating disaccharide unit of 3. and NMR spectra supported that the resulting product is a cellulose-chitin hybrid polysaccharide. Furthermore, it has been proven by CP/MAS NMR spectrum that the white precipitate is also hybrid polysaccharide 3. 

Characterization data of the resulting cellulose-chitin hybrid polysaccharide 3 are summarized in Table 1. The average molecular wei t value (M ) of the resulting product 3 via cellulase- and chitinase catalyzed polymerization reached to 2840 and 4030, which correspond to 15-16 and 22 saccharide units, respectively. 

A cellulose-chitin hybrid polysaccharide with alternating P(1 4)-linked D-glucose (Glc) and N-acetyl-D-glucosamine (GlcNAc) was synthesised via two modes of enzymatic polymerisation [226]. First, a sugar oxazoline monomer of GlcP(1 4)... 

Cellulose-Xylan Hybrid Polysaccharide (46) and Chitin-Xylan Hybrid Polysaccharide (47)... 

Here, compounds 10 and 13 were chemically synthesized as monomers for the synthesis of cellulose-xylan hybrid polysaccharide 11, and chitin-xylan hybrid polysaccharide 14, respectively (Figure 8). 

A cellulose-chitin hybrid polymer, a nonnatural polysaccharide having a glucose unit and an N-acetyl glucosamine unit alternatingly in the main chain, was synthesized by chitinase-catalyzed polyaddition of a disaccharide oxazoline monomer in an aqueous solution (44). 

Natural polysaccharides like cellulose or amylose can be obtained via polycondensation reactions, while chitin and glycosaminoglycans (GAGs) are synthesized by ROP [49]. One group of uimatural polysaccharides is hybrid polysaccharides obtained from two different polysaccharide components and is very difficult to synthesize via conventional chemical synthesis. 

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