Glucuronic acid residue

In the cell-wall antigen from Staphylococcus aureus M, taurine is linked as an amide (51) to a 2-acetamido-2-deoxy-D-galactosyluronic residue. l-Threonine and L-glutamic acid are linked as amides to D-glucuronic acid residues in the LPS from Rhodopseudomonas sphaeroides ATCC 17023 and in the capsular polysaccharide from Klebsiella K82, respectively. In the capsular polysaccharide from E. coli K54, L-serine and L-threonine, in the ratio 1 9, are linked to the carboxyl group of a D-glucuronic acid residue. In the capsular polysaccharide from Haemophilus influenzae type d,... 

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. 

In contrast to L-iduronic acid residues, most of which are sulfated at C-2, D-glucuronic acid residues in heparin and heparan sulfate are largely or exclusively nonsulfated. This was especially proved by their susceptibility to periodate oxidation,123 and through characterization of D-glucuronic acid-containing di- and tetra-saccharides from deamina-tive104 109 110 138 or heparinase - heparanase cleavage137,145 of heparin. 

From pig mucosa. Notations as for Scheme 1. Major products (yield 40-80% of original heparin). Major disaccharide fraction (50-80%). From heparin chains terminating with a D-glucuronic acid residue at the reducing end. Minor products (yield <3% of original heparin). From the active site for antithrombin (asterisk denotes 3-C-sulfation of the amino sugar or anhydro-D-mannose). 

Scheme 4. —Smith Degradation of Heparin (Arbitrary Sequence). (R = remnant from a D-glucuronic acid residue.)...

The first constitutional studies were made by Schmiedeberg97 who gave a general idea of the type of structure in chondroitin. Levene considered that the molecule was a tetrasaccharide composed of two glucuronic acid residues conjugated with two units of chondrosamine, esterified with sulfuric acid. On hydrolysis with hydrochloric acid the... 

Reeves and Goebel72 have shown that hydrolysis of the reduced methylated capsular polysaccharide of Type III pneumococcus yields 2,3,6-trimethyl-D-glucose and the anomeric forms of methyl 2,4-dimethyl-D-glucoside. The cellobiuronic acid units in the polysaccharide are thus linked through position 3 of the D-glucuronic acid residue, probably by /3-D-linkages. That is, the polysaccharide contains alternate 1,3-and l,4-/3-D-linkages. 

The repeat distance is 18.6 A (1.86 nm), with a meridional reflection on the first layer-line. A tetrasaccharide repeating-unit was favored. It was suggested that the linkage between the 2-acetamido-2-deoxy-D-glucose and D-glucuronic acid residues is alternately a-D-(l — 4) and /3-d-(1 — 4). 

Figure 3.8(a) Possible ester linkage between an a-OH of lignin and a carboxyl group of a 4-0-methyl-/3-d-glucuronic acid residue on the xylan backbone. 

In contrast to alkaline pulping, the acetyl groups of the hemicellu-loses are relatively stable at low pH, as are the glucuronic acid residues of the xylans. The main effect of high temperature and low pH is the hydrolysis of the glycosidic linkages in the polysaccharide... 

The simple self-crosslinking treatment also crosslinks GAG chains to collagen [30]. The reaction kinetics are outlined in Fig. 2. The mechanism probably involves condensation of amino groups of collagen with carboxylic groups of glucuronic acid residues on the repeat unit of chondroitin 6-sulfate. Dehydra-... 

Fig. 2. Kinetics of cross-linking of chondroitin 6-sulfate, a glycosaminoglycan (GAG), to collagen following exposure to 105 °C under 6.7 Pa (50 mtorr). The mechanism of cross-linking is most probably interchain amide condensation involving e-amino groups of lysyl residues on collagen chains with carboxylic groups on glucuronic acid residues in neighboring GAG chains (From [30] with permission).

In the sequence analysis of the Klebsiella type 59 capsular polysaccharide, the terminal D-glucuronic acid residue was eliminated... 

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