Polysaccharide structural studies

The direct separation of polyhydric alcohols does not appear to have been used in polysaccharide structural studies, except in the case of the methylated compounds that will be discussed in Part II of this article. 

Immunopolysaccharides. Part IV. Structural Studies on the Type II Pneumococcus Specific Polysaccharide, K. Butler and M. Stacey, J. Chem. Soc., (1955) 1537-1541. 

The stems of the tree were foimd to contain polysaccharides consisting of arabinose, galactose and galacturonic acid and only minor amoimts of rham-nose. Structural studies indicate that the polymeric material consists of 1,4-linked galacturonic acid residues, terminal, 1,4-, 1,6- and 1,3,6 galactose units and terminal and 1,5-linked arabinofuranose residues. Further studies must be performed on this in order to determine what type of pectin it can be classified as. The Hnkage data indicate that both AG-I and AG-II are present. This polymer was shown to activate polyclonal B-cells [78]. 

The objective of the project described is to obtain insight in the relation between the chemical fine-structure of polysaccharides from soy bean cell walls and their functional properties in industrial products and how they effect processing. Soy meal is of great importance in the feed industry. The application of the (modified) soy bean cell wall polysaccharides as a food additive will be investigated. The obtained knowledge of the polysaccharide structures will also be used in studies concerned with the improvement of the in vivo digestibility of these polysaccharides. 

Structural studies of a pectic polysaccharide from Plantago major L. 

A structural study on lipid A and the O-specific polysaccharide of the lipopoly-saccharide from a clinical isolate of Bacteroides vulgatus from a patient with Crohn s disease was conducted by Hashimoto and coworkers [39]. They separated two potent virulence factors, capsular polysaccharide (CPS) and lipopolysaccharide (LPS), from a clinical isolate of B. vulgatus and characterized the structure of CPS. Next, they elucidated the strucmres of O-antigen polysaccharide (OPS) and lipid A in the LPS. LPS was subjected to weak acid hydrolysis to produce the lipid A fraction and polysaccharide fraction. Lipid A was isolated by PLC, and its structure was determined by MS and NMR. 

Structural studies of some 25 of the 80 different capsular polysaccharides from pneumococci have been reported. Complete structures... 

Following with bacterial infections and anti-adhesion strategies,86 88 NMR based structural studies have been conducted on O-polysaccharide chains in these past few years,38 40,42,43 in order to elucidate the molecular basis and the role of the lipopolysaccharides in these pathologies. 

Selective Production of Xylanases by Cellulolytic Microorganisms. Until recently there was little information on common or separate genetic control of cellulase and xylanase synthesis in microorganisms (60). Studies on this subject were complicated by the fact that numerous microbial ceUulases and xylanases are non-specific with respect to cellulose and xylan as substrates. As could be expected from a comparison of both polysaccharide structures, non-specificity is more frequently observed with cel-lulases, because their substrate binding sites can easily accommodate substrate using an unsubstituted p-(l 4)-linked chain of D-xylopyranosyl units. 

Preliminary structural studies of cutin and suberin breakdown involved examination of 13C NMR spectra for insoluble residues that were resistant to chemical depolymerization. In cutin samples, flexible CH2 moieties in particular were removed by such treatments, but CHOCOR crosslinks and polysaccharide impurities were retained preferentially. A concomitant narrowing of NMR spectral lines suggested that the treatments produced more homogeneous polyester structures in both cases. Our current studies of cu-ticular breakdown also employ selective depolymerization strategies with appropriate enzymes (1,28). 

The present article is written primarily from the point of view of the investigator studying polysaccharide structures. In certain cases, how-... 

The analysis of monosaccharide mixtures as the permethylated derivatives was proposed early in the application of gas-liquid chromatography to carbohydrates, but the method has now been superseded by more convenient procedures.230,231 There are, however, situations in which this method is useful, such as during a structural study of a polysaccharide by the methylation technique. The mixture of partially methylated monosaccharides obtained by methanolysis may then be fully methylated, and the proportions of the various monosaccharides determined. This approach has been used, for example, in studies on a galactomannan392 and on tamarind-kernel polysaccharide.393 Such an analysis also constitutes a useful check to ensure that no significant change in the composition of the polysaccharide occurred during methylation. 

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