Dextrans branching patterns

Methylation- or combined methylation-ethylation reactions were used for structure analysis of polysaccharides. The alkylation of dextran can be applied to the investigation of the branching pattern, i.e. the number and length of side chains (Sect. 2.2) [22,23]. The methylation is carried out in liquid ammonia with sodium iodide and methyl iodide, yielding products that are soluble in chloroform and tetrachloroethane [257]. 

Dextran is a unique polysaccharide because of its structure (only glucose units), purity, defined branching pattern depending on the microbial sources and defined molecular weight. Today, it is produced on a commercial scale resulting from optimised biotechnological processes for the biosynthesis of dextran using preferably Leuconostoc mesenteroides. 

The action patterns of a purified, intracellular dextranase and three intracellular a-D-glucosidases from Pseudomonas UQM733 on pure isomalto-oligosaccharides have been studied. The a-D-glucosidases had optimal activity on isomaltotetraose and were therefore classified as oligoglucanases . They have been used to determine the structure of two branched isomalto-oligosaccharides obtained by enzymic degradation of dextran. 

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