Partial acid hydrolysis oligosaccharides

Figure 4. Total ion chromatogram of the methylated mono/oligosaccharide obtained by the partial acid hydrolysis of the bran arabinogalactoglu-curonoxylan.

Table III. Possible Structure of Oligosaccharides Obtained by the Partial Acid Hydrolysis of Rice Bran Arabinogalactoglucuronoxylan...

Structural studies on the oligosaccharide derivatives obtained by partial, acid hydrolysis of fully methylated polysaccharides often furnish valuable information on the positions at which the oligosaccharides were linked in the original polysaccharide. When the folly methylated Klebsiella O group 9 lipopolysaccharide,27 which contains D-galactopyranose and D-galactoforanose residues, was subjected to mild, acid hydrolysis, and the product reduced with lithium aluminum deuteride and remethylated with trideuteriomethyl iodide, a good yield of the disaccharide derivative 10 was obtained. 

SCHEME 11. Two branched oligosaccharides, 44 and 45, obtained after treatment of a polysaccharide from Porphyridium sp. with lithium in ethylenediamine,721 and the structure 46 I m — 2 or 3) of a backbone of this polymer (R = H, sulfate, terminal Gal, or terminal Xyl) proposed according to the data of partial acid hydrolysis.722... 

Little work has been published concerning the isolation of oligosaccharides following graded, acidic hydrolysis of heparin. Wolfrom and co-workers have studied the partial, acid hydrolysis of a carefully purified heparin. (Purification was effected through the benzidine salt and the neutral barium salt was fractionally precipitated from water. The less-soluble fraction, after conversion to the barium acid salt, had a N S ratio of 2 5 and 5 sulfate groups per tetrasaccharide period, consumed 1 mole of periodate per tetrasaccharide period, and was shown to be homogeneous by electrophoresis and by countercurrent distribution. The molecular... 

Despite the fact that many heptoses are by far less prominent in Nature than hexoses these monosaccharides are found both as metabolic intermediates, and as structural carbohydrates of bacterial cell walls.D-Sedoheptulose 7-phosphate is an important intermediate of the pentose cycle, and D-sedoheptulose 1,7-bisphosphate is present in plants as an intermediate of the dark phase of photosynthetic reactions. L-Glycero-D-manno-heptose was isolated from the oligosaccharides obtained by partial acid hydrolysis of the lipopolysaccharide from Escherichia coli K-12 strain W3100 [153] and Haemophilus influenzae [154]. Both L-glycero-D-wtanno-heptose and D-glycero-D-ma o-heptose were isolated from the lipopolysaccharide of Vibrio parahaemolyticus [155]. 

Fig. 24.—Elution analysis of oligosaccharides formed by partial acid hydrolysis of a-dextrin. The last peak at fractions 75-80 consists of unchanged a-dextrin.

Two approaches can be used for partial acid hydrolysis studies. Conditions can be chosen to remove selectively acid-labile residues or, alternatively, the hydrolytic conditions can be such that only residues retaining acid-resistant linkages remain intact. In this section we shall concentrate on methods used to obtain and characterize acid-stable oligosaccharides. 

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