Trisaccharides residue

Similarly to the STARFISH design already described (Fig. 17), the peripheral and radial presentation of five Pk-trisaccharide residues presenting tailored spacers could... 

The analytical data do not exclude the possible presence of some tetra-saccharide residues in the polymer from strain 8191, or of trisaccharide residues in that from strain 39, although no traces of these were detected in partial, acid hydrolyzates. It does seem likely from analyses, however,... 

N,N -D/-z4c 2,3-Diacetamido-2,3-dideoxy-D-rrumnuronic acid C,oH,6N207 276.246 Aminosugar present in Pseudomonas aeruginosa lipopolysaccharide and Vibrio cholerae polysaccharide. Characterised as di- and trisaccharide residues... 

Structure of xanthan has been determined by chemical degradation and methylation analysis (335,336) it is composed of repeating units consisting of a main chain of D-glucopyranosyl residues with trisaccharide side chains made up of D-mannopyranosyl and D-glucopyranosyluronic acid residues. 

Hen egg-white lysozyme catalyzes the hydrolysis of various oligosaccharides, especially those of bacterial cell walls. The elucidation of the X-ray structure of this enzyme by David Phillips and co-workers (Ref. 1) provided the first glimpse of the structure of an enzyme-active site. The determination of the structure of this enzyme with trisaccharide competitive inhibitors and biochemical studies led to a detailed model for lysozyme and its hexa N-acetyl glucoseamine (hexa-NAG) substrate (Fig. 6.1). These studies identified the C-O bond between the D and E residues of the substrate as the bond which is being specifically cleaved by the enzyme and located the residues Glu 37 and Asp 52 as the major catalytic residues. The initial structural studies led to various proposals of how catalysis might take place. Here we consider these proposals and show how to examine their validity by computer modeling approaches. 

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]. 

Note that this is not a true triose but a trisaccharide containing three a-glucose residues. 

Xylose Pentose Xyl UDP-Xyl Xyl is attached to the OH of Ser in many proteoglycans. Xyl in turn is attached to two Gal residues, forming a link trisaccharide. Xyl is also found in t-PA and certain clotting factors. 

Xyl residue, forming a link trisaccharide, Gal-Gal-Xyl-Ser. Further chain growth of the GAG occurs on the terminal Gal. 

The first heteropolysaccharide for which a cyclic structure has been proposed is the enterobacterial common antigen (ECA), which was shown by f.a.b.-m.s. to be a mixture of three cyclic components containing 4, 5, and 6 repeats, respectively, of a previously characterized trisaccharide (31) in which the GlcNAc residues were known to be partially acetylated at 0-6. 

Xanthan (Figure 11) is a commercially important polysaccharide produced by the bacterium Xanthomonas campestris.187 188 The xanthan backbone consists of a P(l-4)-linked D-glucopyranose chain with a trisaccharide side chain attached at C3 to alternate glucose residues. These side chains consist of an acetylated mannose residue, a glucuronic acid residue, and a pyruvate ketal linked to a terminal mannose residue. The acetate and pyruvate content depend on the fermentation and isolation conditions used by the supplier. 

Baddiley and coworkers42 have studied the structure of S13, which is composed of D-galactose, D-glucose, 2-acetamido-2-deoxy-D-glucose, and ribitol residues, and phosphate groups in the molar proportions 2 1 1 1 1. O-Acetyl groups are also present. A neutral pentasaccharide was obtained by hydrolysis with alkali, followed by enzymic dephosphorylation. On mild, acid hydrolysis, this yielded two main products, a trisaccharide (19) and a disaccharide (20), the structures of which were determined by conventional methods. 

Structure 34 was proposed for a trisaccharide composed of d-glucose, D-galactose, and 2-acetamido-2-deoxy-D-galactose residues. The D-glucosyl group and the D-galactosyl residues are the same as in disaccharide 32. That the 2-acetamido-2-deoxy-D-galactose residue is linked to 0-3 was indicated by color reactions and the fact that this... 

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