Type Trisaccharide

The primary cell walls of most higher plant species contain XGs of the XXXG type, which bear trisaccharide side chains (8) on the backbone [247]. The seeds of many plants contain XXXG-type XGs, in which about 30% of the xylose units possess a /3-D-Galp residue attached to position 2. Several plant species produce XGs that lack fucose and galactose, and have a-L-Ara/ attached to 0-2 of some of the Xylp side-chains, such as XG isolated from olive fruit [262] and soybean (Glycine maxima) meal [263]. However, a-L-Ara/ residues occur also 2-linked directly to some of the Glcp residues of the backbone [154]. 

The cell walls of the Solanaceae plant species contain the XXGG type of XGs [247,275]. Suspension-cultured tobacco cells secrete a XG, bearing disaccharide side chains (11) [276], as similarly reported for XGs of other solana-ceous plants. The XG from suspension-cultured tomato cells is more complex, as it also contains the unusual / -L-Ara/-(1 3)-o -L-Ara/-(1 2)-a-D-Xylp trisaccharide side-chain (12) in addition to the prevaiUng dimeric moiety (13) [277]. 

In a recent paper650 the relationships between Rhizobium radicicolum polysaccharides and those of pneumococcus are indicated by crossprecipitin reactions of the former with Types III and VI anti-pneumococcus horse sera. In addition, hydrolysis of the methylated polysaccharide of Rhizobium radicicolum yields equal amounts of 2,3,6-trimethyl-D-glucose, 2,3-dimethyl-D-glucose and 2,3-dimethyl-D-glucuronic acid.65 1 The minimum trisaccharide repeating unit consists, in part, of cello-biuronic acid, and may be represented ... 

K. Matsuoka, M. Terabatake, Y. Esumi, D. Terunuma, and H. Kuzuhara, Synthetic assembly of trisaccharide moieties of globotriaosyl ceramide using carbosilane dendrimers as cores. A new type of functional glyco-material, Tetrahedron Lett., 40 (1999) 7839-7842. 

Action pattern C (see Scheme 1) was observed with the extracellular endo-D-galacturonanase produced by Erwinia caro-tovora.123 It differs from the first two types in a specific hydrolysis of penta(D-galactosiduronic acid) (1) to trisaccharide and disaccharide, and in having only two alternative ways for cleavage of hexa-saccharide. Both bonds are split in the trisaccharide 3. The pentasaccharide is split five times faster than the tetrasaccharide. 

The 3H chemical shifts, coupling constants, temperature coefficients, exchange rates and inter-residual ROEs of the hydroxyl protons of various synthetic type II trisaccharides, analogues of (3-D-Galp-(l - 4)-p-D-GlcpNAc-(l - 2)-a-D-Man-(l - 0)(CH2)7CH3, were reported and interpreted,8 assisted with molecular dynamic simulations, to deduce key information on the conformational behavior of these important molecules in aqueous solution. 

Mass spectrometry enables the type of direct analyses described, but it does have its limitations. Online operation forces detection at infusion concentrations, in salty buffer and under complex mixture conditions. General ion suppression results from the buffer and mixture components, and mixture complexity can tax the resolution of even the best mass spectrometers. Increasing compound concentration is not the answer, as this leads to problems of solubility and increased compound consumption. We have found that the online method can work successfully for up to 100 compounds per analysis, but the false negative rate becomes appreciable [21]. As an alternative for ligand discovery purposes, we have developed a FAC-LC/MS system in which FAC effluent is sampled and analyzed by LC/MS [19]. This system offers the ability to concentrate mixture components and introduces another dimension to the data in order to tolerate more complex mixtures (Fig. 6.9). Using this system, we have screened approximately 1000 modified trisaccharide acceptor analogs targeting immobilized N-... 

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