Oligosaccharides

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Oligosaccharides ( Greek : oligos - little) are carbohydrates (sugars) that are made up of several identical or different monosaccharides (simple sugars) and are linked by glycosidic bonds . Depending on the number of monosaccharide units present, one speaks of di- , tri- , tetra- , pentasaccharides , etc., which can be both linear (unbranched) and branched. Compounds of many monosaccharides are called polysaccharides . The distinction between oligosaccharides and polysaccharides is fluid, but in the case of oligosaccharides one usually assumes three to ten connected monosaccharides. According to another source, oligosaccharides consist of two to ten monosaccharide units.

properties

The physical and sensory properties are similar to those of monosaccharides . This also applies to the reactions, in which, however, the difference between reducing and non-reducing oligosaccharides must be observed. The non-reducing ones do not show the reducing power , mutarotation and the reactions with alcohols and amines . Since they are glycosides , oligosaccharides can be easily hydrolyzed by acids , but are stable to bases .

Galactooligosaccharides ( GOS ) consist of one to seven galactose and one glucose unit; they do not occur in cow milk but in breast milk and have a bifidogenic ( prebiotic ) effect . Some oligosaccharides have antibiotic effects.

biochemistry

Oligosaccharides are often attached to proteins and lipids, e.g. B. bound in the cell membrane and play a role in cell recognition. Among other things, they determine the blood groups according to the AB0 system .

Individual evidence

  1. ↑ Entry on oligo . In: IUPAC Compendium of Chemical Terminology (the “Gold Book”) . doi : 10.1351 / goldbook.O04282 Version: 2.1.5.
  2. ^ Siegfried Hauptmann : Organic Chemistry , 2nd revised edition, VEB Deutscher Verlag für Grundstoffindindustrie, Leipzig, 1985, pp. 649–651, ISBN 3-342-00280-8 .
  3. ^ Hans-Dieter Belitz , Werner Grosch , Peter Schieberle : Textbook of food chemistry . 6th completely revised edition. Springer, Berlin / Heidelberg 2008, ISBN 978-3-540-73201-3 , doi : 10.1007 / 978-3-540-73202-0 .
  4. ↑ Entry on oligosaccharides. In: Römpp Online . Georg Thieme Verlag, accessed on February 23, 2012.
  5. ↑ F. Horn et al. a .: Human biochemistry , Georg Thieme Verlag Stuttgart, 2005, ISBN 3-13-130883-4 .