Polysaccharides structural heterogeneity

Chemoenzymatic synthesis of HS was first employed in the synthesis of structurally heterogeneous polysaccharides. In this method, a bacterial capsular polysaccharide isolated from the E. coli strain K5 is subjected to a series of enzymatic modifications, including N-sulfonation, epimerization, and 2-0-, 6-0-, and 3-O-sulfonations [26-28],... 

Glycans with 1,2-, 1,3-, and particularly 1,6-linked units have a more irregular, loosely jointed structure. The heterogenicity of the polysaccharide structural units and their volumes introduce further regularities or irregularities in the macrostructure. A decrease in the group polarity, e.g., by methylation, and number results in a more irregular polysaccharide structure. 

Xylan is a major structural heterogeneous polysaccharide found in plant biomass and represents the second most abundant polysaccharide in the biosphere, after cellulose. The abundance of xylan and its integral association within the plant cell wall makes it a key... 

Biofilms can form on just about any imaginable surface metals, plastics, natural materials (such as rocks), medical implants, kitchen coimters, contact lenses, the walls of a hot tub or swimming pool, hmnan and animal tissue, etc. Indeed, wherever the combination of moisture, nutrients, and a surface exists, biofilms will likely be foimd as well. Biofilms are characterized by structural heterogeneity, genetic diversity, complex community interactions, and an extracellular matrix of pol)uneric substances. Biofilms are an important link in the energy budget of many natural commimities. Both types of cells produce a pol)uneric extracellular slime layer which encloses the cells. This complex aggregate of cells and polysaccharide is the biofilm community. 

Hemicelluloses are a structurally heterogenic group of polysaccharides, which vary in their monosaccharide composition, glycosidic linkage content, substitution pattern and degree of polymerisation (Table I) (i). The primary structure of hemicelluloses depends on the type of plant and may even vary between different parts of the same plant (J-5). The term hemicellulose itself is not very clear. It is rather loosely defined as plant cell wall polysaccharides which are closely associated with cellulose (6). Hemicelluloses are often water soluble in native form but extractable in larger amounts only with alkaline solutions due to the complex multilayer structure of the cell walls. 

The first practical CSP derived from polysaccharides is cellulose triacetate (21, Figure 3.10) prepared by Hesse and Hagel in 1973.94,95 Since this derivative was prepared by the heterogeneous acetylation of native microcrystalline cellulose (Avicel) in benzene, it has been postulated that its structure is closely related to that of native cellulose (form I). This has been called microcrystalline cellulose triacetate (CTA-I). CTA-I shows characteristic chiral... 

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