Polysaccharides, iii

Sarko A, Muggli R (1974) Packing analysis of carbohydrates and polysaccharides, III. Valonia cellulose and cellulose II. Macromolecules 7 486-494... 

Table 4. Effect d the number of altropyianose units in mixed polysaccharide (III) on the rate constant of the acetylation reaction ...

According to these data, an increase in the content of altropyranose units in the macromolecule of mixed polysaccharide (III) leads to a sharp fall in its acetylation rate as compared with cellulose. Similar results have been obtained for the nitration reaction of (III). An analogous relationship is observed for mixed polysaccharide (IV) upon acetylation preceded by the activation of the starting material. 

The presence of axial OH groups caus a reduction in the rate of esterification ctf mixed polysaccharide (III). 

We have studied the relative reactivity of cellulose and mixed polysaccharides (III) and (IV) in reactions with aqueous and alcoholic solutions of NaOH. The data on the composition of alkali compounds of polysaccharides are given in Table 6. As seen from the data presented in Table 6, the amount of bound alkali in preparations of alkaline compounds of mixed polysaccharides is le than in alkali cdlulose obtained under the same conditions, the DS with respect to NaOH decreasing with increasing content of altrose units in polysaccharide (III) and of 3,6-anhydroglucose units in polysaccharide (IV). 

Table 6. Effect of number of altrose or 3,6-anhydroglucose units in the macromolecule of a mixed polysaccharide on the composition dl alkaline compounds of polysaccharides (III) (IV)...

Fig. 2. Isothenns of the sorption of water vapor by the following preparations / hydrate cellulose 2 mixed polysaccharide (III) containing 10 mol.-% of altro-pyranose units 3 mixed polysacdkride (III) containing 31 mol.-% of altropyranose units 4 cotton cellulose 5 mixed polysaccharide IV containing 3,6-anhydro-...

Table 8. Sorption of iodine and heats of swelling of cellulose and mixed polysaccharide (III) in water...

It should be noted that it is not only preparations of mixed polysaccharides which differ from cellulose in solubility, but also esters (acetates, nitrates) do not dissolve com Jetely m solvents of the corresponding cellulose esters. Thus, the nitrate of mixed polysaccharide(III), which contains 42 mol.-% of altrose, dissolves in acetone to 68%, and the triacetate dissolves in methylene chloride to 65 %. 

The effect of the spatial arrangement of the hydroxyl groups of the repeating unit on reactivity has been investigated in comparative studies of the acetylation and O-nitration of cellulose and mixed polysaccharides (III) and (IV) (19,20). The data obtained are presented in Tables 4 and 5. 

The transformation from cellulose to mixed polysaccharides also induces a change in the structure of the preparation. The data obtained from the radiographic and infrared-spectroscopic investigation of preparations of mixed polysaccharides (III) and (IV) show that even a small number of altrose or 3,6-anhydroglucose units in the macromolecule markedly reduces the intensity of the intermolecular interaction and the degree erf ordering of the preparation as compared with the starting cellulose. 

Additional data on the character of these structural changes were obtained from an investigation of the sorption of iodine by preparations of mixed polysaccharide (III), and the determination of the heats of swelling in water (Table 8) (26). 

The noncellulosic fraction of SB hull polysaccharides consists mainly of xylose and mannose. The acidic polysaccharides that can be extracted from SB hulls in sequential extractions steps (acidic polysaccharides 1-V) are all very similar in structure with interior chains made up of D-galacturonic acid and L-rhamnopyranose residues. These interior acidic chains are associated with side chains consisting of neutral sugars, including L-arabinose and chains of 1 4 linked P-D-galactopyranose residues. In addition, 2-O-P-D-gal-D-xyl and 2-O-a-L-fuc-D-xyl residues also may be present (Aspinall et al., 1966). Although the acidic polysaccharide fractions I—V are similar structurally, upon hydrolysis they may yield different monosaccharide concentrations. For example, acidic polysaccharide III contains 76% uronic acids, whereas fractions IV and V contained approximately 45% uronic acids. Hydrolysis of the acidic polysac-... 

Komatsu S, Ueda H 1925 The constitution of polysaccharides. III. On plant mucilage I. Mem Coll Sci Kyoto Imp Univ 8 51-57... 

It should be emphasized that poly(ICLC) is not a universal adjuvant. When used with serum albumin or pheumococcal polysaccharide III, an inhibition of production of circulating antibody was seen (H. Levy and P. Baker, unpublished observation). With rabies virus or interferon protein as antigens, no effect was noted. Alterations of dosage of poly(ICLC), or of the temporal relationship between antigen and inducer administration, could conceivably give different results. 

Sarko, a., and Muggli, R. Packing Analysis of Carbohydrates and Polysaccharides. III. Valonia Cellulose and Cellulose II. Macromolecules 7, 486 (1974). 

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