Polysaccharides projections

Xanthan Gum. As a result of a project to transform agriculturally derived products into industrially usefiil products by microbial action, the Northern Regional Research Laboratories of the USDA showed that the bacterium TCanthomonas campestris - noduces a polysaccharide with industrially usefiil properties (77). Extensive research was carried out on this interesting polysaccharide in several industrial laboratories during the eady 1960s, culminating in commercial production in 1964. 

L-(-F)-Arabinose is a naturally occurring L sugar. It is obtained by hydrolysis of the polysaccharide present in mesquite gum. Write a Fischer projection for L-(-F)-arabinose. 

Two helices are packed antiparallel in the orthorhombic unit cell. Association of the helices occurs through a series of periodic carboxylate potassium water - carboxylate interactions. An axial projection of the unit-cell contents (Fig. 23b) shows that the helices and guest molecules are closely packed. This is the first crystal structure of a polysaccharide in which all the guest molecules in the unit cell, consistent with the measured fiber density, have been experimentally located from difference electron-density maps. The final / -value is 0.26 for 54 reflections, of which 43 are observed, and it is based on normal scattering factors.15... 

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. 

The aim of this project is to get additional information about the fine structure of pectic polysaccharides. Therefore pectins from red beet were isolated and fractionateid by chromatographic methods. Some results obtained by methylation analysis of these pectin-rich fractions are presented. 

Newman projection 44 of nucleotides 211 of polysaccharide chains 170 quasi-equivalence 348 random coil 69 sickle 44 skew (S) 166 twist (T) 166... 

Model building calculations showed that in the case of this polysaccharide the gauche-trans conformation was preferred for the 0(6) atom of 6-D-glucose at the 1, 6 linkage. Three projections of the most stereochemically favourable model found in these calculations for K38 are shown in Figure 14. 

The final Klebsiella polysaccharide that will be mentioned specifically is KZS, whose chemical structure was determined by Niemann et al (24) (Figure 30). This polysaccharide is of particular interesT because its backbone consists of a similar alternating 1, 3 diequatorial, 1, 4 diequatorial glycosidic linkage geometry to that found in the connective tissue polysaccharides, hyaluronic acid, chondroitin sulphate and dermatan sulphate (25). All these three polysaccharides have exhibited 3-fold helical conformations with axially projected chemical repeats in the range 0.95 - 0.97 nm which is comparable to 0.97 nm found in K25 which also forms a 3-fold helix (14). Further, left-handed helices were found to be more favourable in K25 as has previously been observed in the connective tissue polysaccharides. The similarities between these various different structures is apparent in Figure 31 which shows projections down the axis of K25 and several of the connective tissue polysaccharides. 

Lipids and proteins that are part of cell membranes often are bonded to small polysaccharide groups that project from the surface of the cell. Slight differences in the structures of polysaccharides that are bonded to lipids in red blood cell membranes of humans are responsible for the A, B, and O blood types. Antibodies recognize these groups and cause cells to clump when their surface groups are not the same as those on the cells of the original individual. 

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