Stachyose structure

Very successful experiments were carried out on the oxidation of sucrose, one mole of which needs three moles of periodic acid, with the formation of one mole each of formic acid and a tetraaldehyde. The latter is oxidized by bromine to a tetracarboxylic acid subsequent acid hydrolysis of the oxygen bridges affords a mixture of acids, all of which were isolated and identified. These results brought in 1943 a confirmation of the structure of sucrose which was discussed, and which gained the approval of C. S. Hudson who, before that, was a little doubtful about the furanoid form of the D-fructosyl group. Similar work was done later with trehalose. In the same way, J. . Courtois obtained confirmation of the structure of raffinose, and established that of stachyose. 

Morgenlie95 isolated a tetrasaccharide from Festuca rubra, and elucidated its structure as being 0-a-D-galactopyranosyl-(l- 4)-0-a-D-ga-lactopyranosyl-(l- 3)-a-D-glucopyranosyl /3-D-fructofuranoside. Raf-finose and stachyose co-exist with this tetrasaccharide. 

From the structural point of view, manninotriose has been of critical significance in relationship to its parent tetrasaccharide, stachyose. Almost invariably, structural studies on manninotriose have gone hand-in-glove with complementary studies on stachyose. 

Of greatest structural significance is the easy cleavage of stachyose by acid or invertase to give equimolar amounts of D-fructose and manni-... 

It should be pointed out that Khouri reported,100 in 1910, the isolation of crystalline stachyose from the rhizomes of Eremostachys laciniata. Moreover, the partial structure suggested by Strepkov for labiose is hardly compatible with its lack of fermentability. Further work needs to be done on labiose, to make certain whether it is different from the known oligosaccharides having about this same rotation and similar properties (stachyose, planteose) and, if it is different, to obtain more exact structural details. 

The pure enzyme displayed the preference sucrose > raffinose > 1-kestose > nystose (in a ratio 100 24 10 6). Other carbohydrates such as turanose, cellobiose, melibiose, leucrose, methyl-a-D-glucopyranoside, and stachyose were also tested but their activity was negligible. Thus, the enzyme only recognized sugars containing a sucrose moiety in their chemical structure. The trisaccharide raffinose is equivalent to a sucrose molecule substituted at the C-6 hydroxyl group, whereas... 

The powdered-cellulose, chromatographic assay of the hydrolyzate of methylated stachyose has furnished important structural data. 1,3,4,6-Tetra-O-methyl-D-fructose, 2,3,4,6-tetra-O-methyl-D-galactose, 2,3,4-tri-0-methyl-D-galactose, and 2,3,4-tri-O-methyl-D-glucose were recovered in approximately equimolar quantities the glycosidic 1- 6 bond for the D-glucose residue and for one of the o-galactose residues in stachyose is clearly indicated. 

Raffinose is composed of three monosaccharides galactose, glucose, and fructose. It shares related structures with sucrose and melibiose. It is also related to stachyose, which possesses an additional (1—>6)-linked a-D-galactopyranosyl unit. 

Figure 1.46 Structures of two main tetrasaccharides with a three 0-glycosidic Links. Cellotetraose is representative of a glycose tetrasaccharide and Stachyose of glycoside tetrasaccharide. The 3-letter codebased nomenclature is used. Arrows show chain directions as determined by the convention described in the legend to Fig. 1.45.

T] values are of interest in polysaccharides since they reflect the chemical structure of the molecule. In stachyose (Fig. 22), the values reflect greater segmental motion at the ends of the molecule (43). However in a trisaccharide of a ganglioside the -acetyl-neuraminic acid acts as an anchor (44), similar to the bulky aglycone portion of the ic-strophanthoside where the T- values of the cymarose portion are lower then those of successive g-g-glucopyranose units (45). 

Stachyose occurs in the roots of several species of plants. Deduce the structure of stachyose from the following data ... 

Following is a structural formula for stachyose, a water-soluble tetrasaccharide component of many plants, including lentils and soybeans. Humans cannot digest stachyose, and its accumulation leads to distension of the gut and flatulence. 

Structure. Cryoscopic molecular weight values indicate that verbascose is a pentasaccharide 169). From methylation studies, Murakami concluded that verbascose was a D-galactosyl-substituted stachyose (at C-6 of the terminal D-galactose unit of stachyose). Hot dilute acetic acid removes the D-fructose unit from verbascose to give a tetrasaccharide verbascotetraose (m.p. 240°C. [a] +191.4 (water)). This tetrose has been partially hydrolyzed, with removal of D-glucose, to give the crystalline trisaccharide galactotriose 164)-... 

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