Oligosaccharides stachyose

Contents of oligosaccharides of defatted meals are given in Table 6. Sucrose, rafflnose, and stachyose are the principal sugars present. The polysaccharide ... 

Stachyose and its homologs primarily occur in seeds and storage organs. Later research showed the presence of these oligosaccharides in the leaves of several plants,184 where they accumulate, especially during the winter, at a concentration parallel to that of sucrose. At this concentration, they provide frost resistance to the plant (see Section II,2,f) rather than serving as storage carbohydrates. 

These oligosaccharides may be derived mainly from four basic units of tetrasaccharides isolychnose, lychnose, sesamose, and stachyose. 

Courtois and coworkers1,50 observed that, in plants, the abundance (distribution) of the oligosaccharides of this series is inversely proportional to their molecular weight. However, when a plant organ accumulates these oligosaccharides, this relationship may not hold. Thus, one kg of the seeds of V. sativa gave 1.12 g of stachyose, 2.5 g of ver-... 

The a-D-galactosidase-catalyzed transfer of the D-galactosyl group of an a-D-galactoside to sucrose, raffinose, and stachyose may yield the raffinose family of oligosaccharides.44 The trans-D-galactosylase activity of a-D-galactosidase was demonstrated in 1950 by Blanchard and... 

Occurrence in plants used for human and animal food is very common, so the raffinose oligosaccharides may be of some nutritional significance. For example, the seeds of food legumes often contain raffinose in amounts equal to or greater than the amounts of sucrose. Cottonseed and soybean meals (after oil extraction) are fairly rich in raffinose and stachyose, respectively.80 86... 

Fig. 1.—Molecular-rotation relationships of several raffinose-type oligosaccharides. Me, methyl a-D-galactopy ranoside Gl, D-glucose Mb, melibiose Mt, manninotriose Vt, verbascotetraose S, D-glucitol M, melibiitol Ml, manninotriitol Su, sucrose K, raffinose St, stachyose V, verbascose Gb, gentiobiose Ge, gentianose.

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. 

Minor amounts of soluble carbohydrates, proteins, vitamins, etc., are present in the bark. In addition to starch and pectins, oligosaccharides, including raffinose and stachyose have been detected in phloem exudates. 

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