Dextran hydrolysate

Fig. 3-115. Gradient analysis of a dextran hydrolysate (dextran 1000). - Chromatographic conditions see Fig. 3-113 injection 50 pL of a 0.3% solution.

This observation was supported from changes in M observed during hydrolyses (19) with subsequent analysis of the 3ata on a statistical model of a trifunctionally branched polymer. It was observed that the dispersity as a function of hydrolysis time, for given temperature and pH, exhibits a maximum. No maximum was observed for dextran hydrolyses, which is reported to follow a random path. 

When the slope of the gradient profile is made steeper by adding more sodium acetate per time unit, even higher polymers can be resolved. Figure 3.243 shows this effect with another dextran hydrolysate separation (Dex-tran 5000), where polymers up to DP50 can be detected utilizing a convex gradient profile and a CarboPac PAIOO column. 

Figure 3.243 Gradient analysis of a dextran hydrolysate (Dextran 5000). Separator column CarboPac PA100 eluent see Figure 3.242 gradient 2% B isocratically for 2 min and then...

Fig. 3-183. Gradient analysis of a dextran hydrolysate (Dextran 1000) on CarboPac PA-100. - Eluant (A) 0.1 mol/L NaOH, (B) 0.1 mol/L NaOH -f 0.5 mol/L NaOAc ...

Preliminary examinations of dextran structures were conducted by optical rotation, infrared spectroscopy and periodate-oxidation reactions. More detailed results can be achieved by methylation analysis [19]. The hydroxyl groups are methylated with methyl iodide after activation with sodium methylsulfinyl carbanion (Fig. 2). The methyl dextran is hydrolysed to the corresponding different methylated monosaccharides, which are furthermore reduced and peracetylated. The resulting alditol acetates of methylated sugars are separated by gas chromatography and identified by their retention times. In particular, a combined capillary gas-liquid chromatography/mass... 

Alternate anti-vs procoagulant activity of human whole blood on a LbL assembly between chitosan and dextran sulfate has been achieved [149,150]. Furthermore, the technique permits the formation of biodegradable nanostructures with nanometer-order thickness on surfaces, which is an important requirement for biomedical applications. The alternating enzymatic hydrolysis of a LbL assembly formed from chitosan and dextran sulfate by chitosanase was demonstrated via measurements with a quartz crystal microbalance (QCM) [151]. The hydrolysis of the assembly was clearly dependent on the surface component. The hydrolysis of the assembly with the dextran sulfate surface was saturated within 10 min and was much faster than the hydrolysis of the assembly with the chitosan surface, although chitosanase can hydrolyse chitosan (Fig. 14). 

Interestingly, CDI can also be utilised for the introduction of substituents by inter- or intramolecular coupling of OH moieties of the polysaccharide via a carbonate function. This synthesis was used to obtain dextran with 2-hydroxyethyl methacrylate moieties (dex-HEMA) and dex-HEMA with lactate spacer functions (Fig. 32). A new class of dextran derivatives (DS < 0.2) that can be polymerised containing hydrolysable groups is accessible [177]. 

Colloidal isotonic solutions of macromolecules include dextrans (glucose polymer), gelatin (hydrolysed collagen) and hydroxyethyl starch. 

Certain fractions of partially hydrolysed dextran are used as plasma substitutes or expanders. Certain strains of Leuconostoc meserentoides are cultivated to synthesise dextran (XIII), which is a polymer of anhydroglucose, linked through a-1,6 glucosidic linkages. The chains are branched on the average, one branch occurs for every 10-12 glucose residues. The intrinsic viscosity [ij is related to Mby the relationship... 

Aminosalicyclic acid, bacitracin, blood plasma, blood serum, methicillin salts, culture media, dextran, enzymes, gamma-globulin, hormones, streptomycin, iron dextran, lysine, casein hydrolysate, penicillin, serum hydrolysate, penicillin, serum hydrolysate, tetracycline vitamins, oleandomycin, chloramphenicol succinate salts... 

C12H22O11 342.299 Isolated from partial hydrolysates of amylopectin and dextrans. Prod, by Bacillus polymyxa and Streptomyces spp. Active against E. coli only. Sol. H2O poorly sol. MeOH, C5H5, butanol. 

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