Terminal mannose residue

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. 

Stereoscopic projections for the complex with the a(1- 6)terminal mannose residue in the primary site of ConA in the two possible orientations are shown in Figures 3 and 4. These orientations are slightly different from the one proposed by Carver et al. (13), using NMR and docking studies. 

Carver et al. propose that the middle mannose residue in the trimannosidic core forms hydrogen bonds with the protein whereas in the present study it is the a(l- 3) terminal mannose residue which forms additional stabilizing interactions with the protein. 

Thus the present study shows that ConA interacts with the trimannosidic core by binding preferentially to the a(1- 6)-linked terminal mannose residue at the primary binding site. Depending on the orientation of the a(l- 6) terminal residue in the primary binding site the a(l- 3) terminal mannose residue interacts either with Tyr 100 or His 205 on the surface of ConA (Figures 3 and 4). This indicates that there is no specific extended binding site... 

Mglucerase Injection. Imigluccra.se injection (Cere-ryme) is a form of human placental glucocetebrosida.se from which the terminal mannose residues have been removed. This product is produced through recombinant technology... 

Fig. 3. Concanavaline-A-induced, ligand-binding assay of various liposomal formulations. Concanavalin A solution (lOOgg/mL) was added to 0.2 mL of diluted liposomes formulations and absorbance at 550 nm was measured as a function of time. The data were subtracted from the blank experiment conducted without an addition of concanavalin A. Binding of the terminal mannose residues of the mannan to the ConA causes agglutination of the complex in solution resulting in an increase in turbidity. However, plain liposomes did prevent the binding of Con A as evidenced by the lower turbidity. The accessibility of the mannan to the liposomes is critical for in vivo cell binding...

Xanthan gum can be regarded as a cellulose derivative. The main chain consists of 1,4 linked P-glucopyranose residues. On an average, every second glucose residue bears in the 3-position a trisaccharide of the structure P-D-Man/ -(1 4)-P-d-G1c/ A(1 2)-a-D-Man/7 as the side chain. The mannose bound to the main chain is acetylated in position 6 and ca. 50% of the terminal mannose residues occur ketahzed with pyruvate as 4,6-0-(l-carboxyethylidene)-D-mannopyranose (cf. Formula 4.162 GlcpA glucuronic acid). 

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