Disaccharide-alditol

PA-1 was partially hydrolyzed with O.IM TFA (40°C, 24 h) and the three fractions (PA-l-I, PA-l-II and PA-l-III) were obtained by Bio-gel P-6. Especially, about 50% of TBA-positive material (PA-l-III) was eluted in the fraction of small oligosaccharide. Permethylated oligosaccharide-alditols from PA-l-III were analyzed by GC-EIMS, and three disaccharide-alditols (IP, 2P and 3P) were detected. EI-MS and component sugar analysis suggested that the major peak, IP was Rha-(l- 5)-Kdo-ol and the minor peaks, 2P and 3P were two epimers of Araf-( l->5)-Dha. 

The separation and identification of disaccharides is often an important step in the elucidation of the structure of a natural polysaccharide, and Percival484 has published useful data on the O-trimethyl-silyl derivatives of a variety of disaccharides and their reduction products. In some instances, the trimethylsilyl ethers of the disaccharide alditols have lower retention times than those of the disaccharide derivatives. The per-O-trimethylsilyl derivatives of gentiobi-itol and maltitol were encountered in studies on the structure of Pneumococcus Type II capsular polysaccharide.4843... 

In model studies,224,225 oligosaccharides have been separated as their trifluoroacetates, and Vilkas and coworkers224 found that a tetra-saccharide so esterified had a retention time of six minutes at 250°. Similar results were obtained by Nakamura and Tamura,49 who showed that, on a column of OV-1 at 220°, the retention time of per-0-(trimethylsilyl)sucrose was 12 min, whereas, at 140°, the per(tri-fluoroacetate) required only 7 min. Other comparative data were provided for the common disaccharide alditols. A study of the concentration of lactose in blood was made by using this method 48 it was also shown48 that trifluoroacetylation of disaccharides proceeds more rapidly and satisfactorily in N,N-dimethylformamide than in ethyl acetate. 

Lactose maltose raffinose stachyose sucrose trehalose Disaccharide alditols 20% Silicone rubber 200,220,250... 

If sulfated oligosaccharides, such as the carrabiitol derivatives 21 and 22, are formed as the result of partial reductive hydrolysis directed to determination of the absolute configuration of 3,6-anhydrogalactose, they may be desulfated and acetylated simultaneously.244 Naturally methylated agars give rise to methylated disaccharide alditols. 

The nature of the linkage between the residues in a permethylated disaccharide alditol can be determined by inspection of the fragments formed by cleavage of the alditol chain (cf. Section IV,3 p. 56). 

The mass spectra of trimethylsilylated disaccharide alditols are simplified because of the limited number of fragmentation routes for the alditol moiety. Molecular ions were not seen in the spectra, but, as for the per(trimethylsilyl)ated disaccharides, the (M — CHj) and (M — CH3 — MeaSiOH) can be used to determine molecular weights. The nature of the aldose and alditol residues can be established in the same way as for permethylated disaccharide alditols (see Section VI, 2 p. 89). The fragments formed by a-cleavage of the alditol chain indicate... 

Kochetkov, Chizhov, and their colleagues have demonstrated how m.s. may be used for linkage analysis of di- and tri- saccharides as their per(trimethylsilyl) derivatives. They have extended the method to disaccharide alditols, " which have also been studied by Karkkainen. Kamerling and coworkers " " amplified the selection of disaccharides, and studied the mass spectra of 18 compounds representing all possible linkages from to (l->6). Two groups have investigated the mass... 

With disaccharides containing a 2-amino-2-deoxyaldose reducing residue, it is advantageous to use the A-acetyl derivative, ° or perhaps better still, the A-acetyl derivative of the disaccharide alditol. The oxidation products formed from these derivatives do not become significantly overoxidized, and hence, the stoichiometry of the reaction is clearly indicative of the linkage position. For example, 1 mol of... 

The 0-trimethylsilyl derivatives of five reference disaccharide alditols, composed of 2-acetamido-2-deoxyhexitol substituted at C-3, C-4, or C-6 with a hexose grouping, have been studied by g.l.c.-m.s. The data were used in the determination of the linkage in disaccharide alditols derived from rat brain glycoproteins and gangliosides. 

The structures of disaccharides and disaccharide alditols were revealed by periodate oxidation, reduction and analysis of the products by e.i.- and FAB-m.s. as their peracetyl or permethyl derivatives. The compounds gave simple m.s. with intense and characteristic ions from which the glycosidic linkage positions and ring size could be determined. ... 

Gongalves, A. G., Ducatti, D. R. B., Duarte, M. E. R. Noseda, M. D. (2002). Sulfated and pyruvylated disaccharide alditols obtained from a red seaweed galactan ESIMS and NMR approaches. Carbohydrate Research, 337, 2443-2453. 

Mild hydrolysis, 2. MMB Disaccharide alditols Only for 3,6 AnGal in consecutive carrabiose or agarobiose unik. 

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