Poly saccharides

All carbohydrates (mono-, di- and poly saccharides) give the Molisch colour test for details, see Section III,139,(i). ... 

It is sometimes desirable to draw Haworth formulae with the ring in other orientations (see Chart II), when there are bulky substituents to be represented, or when linkages in oligo- or poly-saccharides are to be shown. If the ring is inverted [as in (g)-(l)], the numbering runs counterclockwise. 

The treatment of sucrose with anhydrous HF89 results in the formation of a complex mixture of pseudooligo- and poly-saccharides up to dp 14, which were detected by fast-atom-bombardment mass spectrometry (FABMS). Some of the smaller products were isolated and identified by comparison with the known compounds prepared86 88 a-D-Fru/-1,2 2,1 -p-D-Fru/j (1), either free or variously glucosylated, was a major product, and this is in accord with the known stability of the compound. The mechanism of formation of the products in the case of sucrose involves preliminary condensation of two fructose residues. The resultant dianhydride is then glucosylated by glucopyranosyl cation.89 The characterization of this type of compound was an important step because it has permitted an increased understanding of the chemical nature of caramels. 

The FTIR spectra of citrus pectin and wheat straw XRPP (Figure 1) appeared to be similar. Both of the spectra have absorptions at 1740, 1608, 1430, 1360, 1244, 1080, 1060, 1035, 890 and 524 cm. The pectic substances belong to a class of carboxy poly saccharides which differ from neutral polysaccharides, with an intense band in the region 1740 cm l (for salts 1608 cm ) related to vibrations of the carboxyl group... 

Figure 15.14 Study of the sample from the Dogon statuette 71.1935.105.169. (a) Optical microphotograph (b) SEM micrograph showing the layer structure ToF SIMS images of (c) proteins, (d) polysaccharides and (e) stearic acid (f) superposition of the distribution of poly saccharides and stearic acid (see colour Plate 9)...

Even if the main focus on the research activities were directed towards structural studies on carbohydrates of natural origin, the synthesis of model substances, deriva-tization of oligo- and poly-saccharides, oxidation, and reduction of carbohydrates, and identification of the products all were performed during this time. 

Besides di- and poly-saccharides, zeolites have been applied for hydrolysis of simple glycosides as described by Le Strat and Morreau.132 Methyl a- and /i-D-glucopyrano-sides were treated with water in the presence of dealuminated HY faujasite with an Si/Al ratio of 15, at temperatures ranging between 100 and 150 °C. It was observed that the reaction rate for the (i glycoside was about 5-6 times higher than that for the oc anomer, a result that might arise from the shape-selective properties of the zeolite and stereoelectronic effects on the surface of the solid. 

Oligo- and Poly-saccharide Synthesis with Sucrose Analogues... 

Gibbs energy change is available to enable synthesis of oligo- and poly-saccharides by sucrose-type enzymes that use sucrose as a substrate for the transfer of glucose or fructose. 

Molecular weight Glycosyl sequence in oligo- and poly-saccharides... 

Especially noteworthy are the methods for determining the sequence of glycosyl residues in a complex oligo- or poly-saccharide. Methods of this type generate a series of overlapping oligomers that are separated and identified by l.c., in conjunction with either direct or indirect mass spectrometry. Most of these methods are still in the developmental stages, and they often require expensive and not-routinely available equipment (see also. Section IV,2) (see Addendum). 

Subjecting monosaccharides to conditions of acid hydrolysis is only of importance in measuring the expected hydrolysis losses during hydrolysis of oligo- and poly-saccharides. Hydrolysis losses may be predicted, based on either the absolute or the relative decomposition of monosaccharides. Absolute decompositions are based on decomposition of monosaccharides. Relative decompositions are based on studies wherein several methods of hydrolysis were applied to the same samples for various lengths of time in this Section, these are classified under the type of acid that causes the least decomposition (that is the largest yield of monosaccharides liberated), because this acid is usually the one of principal concern in the particular study. 

Poly- saccharide Monosaccharide 1 Monosaccharide 2 Linkage Branch- ing Occurrence Function... 

These experiments provide identification of the through-bond spin coupling network as well as through-space proximity between spins. Examples of the application of these techniques have demonstrated the efficiency of these techniques in establishing the assignment, sequence and linkage site information for oligo- and poly-saccharides [59-60, 62-65], and for saponins [29]. 

The similarity of the products obtained from the mono- and the di-saccharides supports the hypothesis of Jezo20 68 and Jezo and Luz k30 that the di- and poly-saccharides are first hydrolyzed to the monosaccharides. Although most glycosidic linkages are stable to... 

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