Dextran structure, enzymic analysis

Furthermore, structural investigations were carried out by the use of degradative enzymes of known specificity followed by means of thin-layer chromatography, HPLC and 13C NMR spectroscopy [12,16]. Table 1 shows examples of the linkage analysis of several dextran fractions produced by different bacterial strains. 

Both and H n.m.r. measurements on a bacterial dextran and its acetylated derivative and on a synthetic tri-O-benzyldextran have revealed the main features of their linear a-(l - 6)-linked structures. Bacterial dextrans from Streptococcus viridans B-1351, Streptobacterium dextranicum B-1254, and four strains of Leuconostoc mesenteroides have been subjected to methylation analysis.They differed with respect to the ease of methylation and subsequent hydrolysis of the methylated polysaccharides, owing to significant differences in the frequency and type of chain-branching. An enzymic approach has been used to obtain information on the frequency and distribution of chain-branching in dextrans. Thus, B-512 native dextran was treated with an endo-dextranase (from Pseudomonas UQM 733) and the products were examined by quantitative t.l.c. The relative amount of each oligosaccharide (i.e. linear isomalto-oligosaccharides of DP 2-5... 

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