Dextrans 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. 

Gluco-oligosaccharides (GlcOS) can be made by the action of an enzyme, dextran dextrinase produced by Gluconobacter oxydans on maltodextrins. They have been made in whole-cell bioreactors [104] and evaluated in fecal batch cultures [105] and in three-stage gut models [106]. Mountzouris et al. [104] used methylation analysis to determine the linkages of... 

Analysis of plasma lipids. HDL was separated by selective precipitation of veiy-low-density lipoprotein (VLDL) and low-density lipoprotein (LDL) by dextran sulphate and manganese chloride (20), and HDL cholesterol was measured by cholesterol determination of the clear supernatant fraction. Cholesterol and triglycerides were analysed by enzymic procedures (21,22). 

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... 

The release of blue dextran from the microspheres was studied in 25 mM buffer phosphate solution (pH 7.5) incubated in a rotatory shaker at 200 rpm and 37 C. Biocatalytic release of azo-BSA and sulfanilic acid from the microspheres was performed with subtilisin or lipase in 25 mM Tris-CIH buffer solution (pH=7.8) incubated at 200 rpm and 37°C. Azo-BSA and sulfanilic acid were determined spectrophotometrically at 334 nm. The presence of sulfanilic acid in the supernatant was assayed after precipitation of azo-BSA with 5% TCA for 15 minutes at 0°C, followed by centrifugation (10,000 xg, 20 minutes at 4°C). Controls without enzymes, and with protease previously inhibited with 1.0 mM diisopropyl fluorophosphate, or thermal inactivate lipase (heated at 100 C) were included. Chemical release of BSA from the microspheres was performed by incubating the microspheres in a buffer phosphate (100 mM, pH=7.4) until total microsphere disintegration. For CD analysis of BSA, samples were filtered through 100 kDa. MWCO devices (Centricon, Millipore, Billerica, MA, USA). 

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