Tetra-, and Pentasaccharides

Occurrence. The sugar is found in the rhizomes of many species of Gentian. 

Preparation (137). Powdered gentian root is extracted with 90% alcohol and the sugar isolated from the extracts. 

Properties. Amorphous [a]f +160 (water). Not fermented by a commercial bakers yeast that ferments maltose. Reducing. 

Occurrence. The trisaccharide is present as a unit in starch, and is prepared by chromatographic resolution of an enzymic hydrolyzate of the polysaccharide 1S9). 

Polymer Homologs. As for cellulose (see Cellobiose), partial hydrolysis of amylose leads to a mixture of linear polymers which may be separated chromatographically into fractions with degrees of polymerization from 1 to 7 142). 

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The final product concentration depends significantly on the ratio of substrate and acceptor. The first acceptor product (panose in the presence of maltose) is favored at high maltose in excess, further tetra- and pentasaccharides are formed in significant amounts.37 Thus isomalto-oligosaccharides (IMOS) can be produced in good yield under appropriate reaction conditions (see Section III). 

The generality of this strategy was investigated by the preparation of a small carbohydrate library of tri-, tetra-, and pentasaccharides (Table 11.1). This protocol quickly becomes burdensome if libraries (rather than single targets) are desired since it requires isolation of every intermediate. We pursued one-pot methods as a practical and more efficient alternative. (See Scheme 11.11.)... 

Mannose tri-, tetra- and pentasaccharide together with GM1 octasaccharide were a gift from Dr. M.A. Chester (Lund, Sweden). At the time of writing, these standards are no longer available. Pentasaccharides (from human urine) and sialylated tetra-saccharides (from human milk) are available from Sigma however, they are cost-prohibitive for routine use. 

In another application of catalytic glycosylation with triflic acid, two disaccharides were synthesized with donors bearing trichloroacetimidate function and then the disaccharides thus prepared were condensed in a similar manner to a tetrasaccharide757 (1,2-dichloroethane, 55°C, 1.5 h, 50-85% yields). The same protocol was used in the synthesis of a decasaccharide from mono-, tetra-, and pentasaccharide building blocks.758 The trichloroacetimidate procedure has been successfully used in the glycosylation of /3-cyclodextrins promoted by triflic acid.759 760... 

Cheung, M K, Douglas, N L, Hinzen, B, Ley, S V, Pannecoucke, X, One-pot synthesis of tetra- and pentasaccharides from monomeric building blocks using the principles of orthogonality and reactivity tuning, Synlett, 257-260, 1997. 

L. A. Mulard, M.-J. Clement, A. Imberty, and M. Delepierre, Synthesis of ligands related to the O-specific polysaccharides of Shigella flexneri serotype 2a and Shigella flexneri serotype 5a. Part 7. Convergent synthesis, NMR and conformational analysis of tetra- and pentasaccharide haptens of the Shigella flexneri serotype 5a O-specific polysaccharide, Eur. J. Org. Chem, (2002) 2486-2498. 

L. A. Mulard and J. Ughetto-Monfrin, Linear synthesis of the methyl glycosides of tri-, tetra-, and pentasaccharide fragments of the Shigella flexneri serotype 5a O-antigen, J. Carbohydr. Chem., 19 (2000) 503-526. 

During the incubation of starch a-dextrins with maltase-containing saliva for 2-3 months, small proportions of panose are formed. This probably represents the action of the maltase impurity on true tetra- and pentasaccharide a-limit dextrins, rather than a third stage of hydrolysis. 

Recently we found that methylated oligosaccharide-alditol methyl esters can he resolved by reverse-phase HPLC (O Neill et al., 1986a, b, c). The technique has been applied to the separation and characterization of acidic tri-, tetra-, and pentasaccharide derivatives from a number of bacterial polysaccharides (O Neill et al., 1986a, b, c). A similar procedure can be used to establish the structural features of cell wall polysaccharides... 

Scheme 11 Assembly of an S. pneumonia Type 9A tetra- and pentasaccharide...

Alpe M, OscarsOTi S (2003) Synthesis of tetra- and pentasaccharides corresponding to the capsular polysaccharide of Streptococcus pneumoniae type 9A L, 9N and 9A. Carbohydr Res 338 2605-2609... 

More complex tri, tetra-, and pentasaccharides, each with more than one type of glycosidic linkage, can also be represented, as shown in Fig. 6.23D. When... 

It was, nevertheless, discovered that the E. coli strain expressing NodC was able to produce, in vivo, small amounts of chitin oligosaccharides these were characterized by mass spectrometry [17]. The product consisted of a mixture of di-, tri-, tetra- and pentasaccharides, and purification involved several steps. The use of... 

Figure 2. Dependence of the NOE enhancement (r ) on the motional correlation Tc under steady state conditions [24]. The spectrometer frequency co was set at 500 MHz. The size of tetra- and pentasaccharides usually leads to molecular tumbling times Tc that cause the NOE to become zero or very close to zero.

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