Amino sugar

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Structural formula of α- D -glucosamine, the first amino sugar discovered

Aminosugars are monosaccharides ( simple sugars ) in which one or more hydroxyl groups (–OH) have been formally replaced by an amino group (–NH 2 ). Free amino sugars are strongly basic and do not occur in nature; the monosaccharides are always components of glycosides and polymeric substances. As building blocks of various, often essential biomolecules , they are fundamental for many central chemical processes and molecular structures in nature.

If the nitrogen is bound to the carbon atom of the anomeric center of a monosaccharide, the amino sugar in question is called glycosylamine , otherwise it is called aminodeoxy sugar .

This group of substances has been discovered in 1875 by the young medical Georg Ledderhose when he scissors and tanks of a recently consumed lobster einkochte in hydrochloric acid and then glittering crystals ( D -glucosamine - hydrochloride discovered). The first description followed the following year, the first synthesis in 1903 (by Fischer and Leuchs ), and in 1914 Phoebus Levene and FB La Forge discovered D- galactosamine . The detection of amino sugars in the influenza virus took place in 1947 (by CA Knight).

Function and meaning

In the nature

N-acetylneuraminic acid (sialic acid) : an amino sugar that is part of the glycocalyx and is responsible for the breakdown of glycoproteins from the blood

Amino sugars are important in a wide variety of organisms as part of their cell structure : for example, they strengthen the cell wall of bacteria with murein , act as a building block of chitin in arthropods and fungi and represent the group of glycosaminoglycans , which are fiber materials and components of cell membranes in many higher living organisms and the basic substance of the extracellular matrix , which are also present in blood and human milk . In general, 2-deoxy-2-amino aldoses such as D- glucosamine or D- galactosamine are the most important amino sugars. However, even with nucleotides , the coding basic building blocks of DNA , it is a question of substituted glycosylamines.

Due to their amino groups, amino sugars are also a relevant factor for the nitrogen content of soils : an estimated 5–10% of the soil nitrogen is due to them, the majority of which comes from dead microorganisms , whereas plants do not produce amino sugar in significant quantities. In intensively cultivated soils, the proportion of aminosugar is measurably reduced, as bacterial synthesis decreases significantly as a result of industrial land use; In addition, differences in the proportion of certain amino sugars occur between differently cultivated soils (between those of bacterial origin, the concentration of which falls more sharply as a result of arable use, and those derived from chitin), which means that the relationship between the two groups can be used as an indicator for land use influences.

use

Kanamycin : An antibiotic produced by Streptomyces kanamyceticus that is used in therapy and research. As also z. B. in the gentamicins there is no ring oxygen in the middle subunit, so that, strictly speaking, the entire molecule is no longer a sugar.

A number of glycosidically bound amino sugars are characteristic of aminoglycosides , which act as antibiotics on the protein synthesis of bacteria in such a way that proteins of nonsensical composition are then formed. In addition, sialic acid analogs are used as neuramidase inhibitors to combat viral diseases such as influenza , but these are not themselves sugars . Furthermore, the physiologically in the will mast cells formed cofactor of the anticoagulant , antithrombin III , heparin as anticoagulant used.

With the Amadori rearrangement can be obtained from aldose - N - glucosides corresponding ketose - N glucosides gain, which are important intermediates in the manufacture of osazones , Osonen , quinoxalines and vitamins Riboflavin (B 2 ) and folic acid (B 9 are).

Since amino sugars show a particularly strong magnetic coupling , it has also been proposed to use them - instead of the previously used proteins - as coordination partners for the metal centers of synthetic catalysts .

chemistry

Free amino sugars have a strongly basic reaction, which is why they are acetylated in living organisms . Naturally, amino sugars from hexoses , which include mannose , glucose (grape sugar) and galactose, are particularly common . Since the hydroxyl group of the C2 atom is preferably replaced, 2-amino-hexoses are often formed: glucosamine is formed from glucose, mannosamine from mannose and galactosamine from galactose.

biosynthesis

The biosynthesis of the amino sugars takes place via a transamination , whereby the amino group comes from the amino acid glutamine . For example, glucose-6-phosphate is aminated to D- glucosamine-6-phosphate by the enzyme hexose phosphate transaminase . The glucosamine phosphate formed can be converted into the N-acetyl derivative with the aid of a transacetylase. After conversion to 1-phosphate, this is activated by reaction with UTP and then incorporated into a wide variety of polymer compounds.

Laboratory synthesis

There are several ways to make amino sugars. A method is a ring-closing reaction from the aldol between dialdehydes and nitroalkanes . For example, sucrose can first be split oxidatively with lead (IV) acetate and acetic acid on the ring of the fructofuranose subunit , then closed again via reaction with nitromethane in the presence of sodium methoxide and methanol , and then the nitro group can be reduced to the amino group .

Top left sucrose, after ring cleavage with lead (IV) acetate (LTA) and acetic acid, a dialdehyde top right, then incorporation of nitromethane and finally reduction of the nitro to the amino group

A more recent synthesis route for aminodeoxy sugars is the synthesis of 1-hydroxy-1,2-benziodoxol-3 (1 H ) -one-1-oxide (“IBX”) mediated from glycals .

Analytics

2-acetamido sugars can be detected by the Morgan-Elson reaction . Furans are formed under basic conditions , which are then reacted with Ehrlich's reagent .

literature

  • Debenham et al .: Recent Advances in N-Protection for Amino Sugar Synthesis . In: Liebigs Annalen, year 1997, issue 5, pp. 791–802.
  • Suzuki et al .: Rapid analysis of amino sugars by microchip electrophoresis with laser-induced fluorescence detection . In: Electrophoresis, Volume 22, Issue 18, pp. 4023-4031.

Individual evidence

  1. ^ A b Peter, Vollhardt: Organic Chemistry , Wiley-VCH, Weinheim 1990. ISBN 3-527-26912-6 , p. 1102.
  2. ↑ Kuhn et al .: Amino sugar . In: Angewandte Chemie, year 69 (1957), issues 1–2, pp. 23–33, especially p. 26.
  3. ↑ a b Ternes, Täufel, Tunger, Zobel: Lexicon of food and food chemistry. Pp. 74-79. Wissenschaftliche Verlagsgesellschaft, Stuttgart 2007. ISBN 978-3-8047-2275-0 .
  4. ↑ Entry on amino sugar. In: Römpp Online . Georg Thieme Verlag, accessed on June 13, 2014.
  5. ↑ Roberts et al .: Free amino sugar reactions in soil in relation to soil carbon and nitrogen cycling . In: Soil Biology and Biochemistry, 39 (2007), pp. 3081-3092.
  6. ^ Zhang et al .: Amino sugars in soils of the North American cultivated prairie . In: Journal for Plant Nutrition and Soil Science, Volume 160 (1997), Issue 5, pp. 533-538.
  7. ↑ Bruice: Organic Chemistry . S. 1150. Pearson Studium, Munich 2007. ISBN 978-3-8273-7190-4 .
  8. ^ Lüllmann, Mohr, Hein: Pocket Atlas of Pharmacology . Pp. 280-281,290,150. Thieme, Stuttgart 2004. ISBN 3-13-707705-2 .
  9. ↑ Entry on Amadori rearrangement. In: Römpp Online . Georg Thieme Verlag, accessed on June 13, 2014.
  10. ↑ Wegner et al .: New building blocks for the design of multicore copper complexes based on amino carbohydrates . In: Angewandte Chemie, Volume 112 (2000), Edition 3, pp. 608–612.
  11. ↑ Science Online Lexicon: Entry on amino sugar in the Lexicon of Chemistry .
  12. ↑ Löffler, Petrides, Heinrich: Biochemistry and Pathobiochemistry . Pp. 544-545. Springer, Heidelberg 2007. ISBN 3-540-32680-4 .
  13. ↑ Shing: Glycol Cleavage Reactions . In: Trost, Fleming (Ed.): Comprehensive organic synthesis: selectivity, strategy and efficiency in modern organic chemistry . P. 712, Volume 7. Pergamon Press, 1991. ISBN 0-08-035929-9 .
  14. ^ Nicolaou et al .: Novel IBX-Mediated Processes for the Synthesis of Amino Sugars and Libraries Thereof . In: Angewandte Chemie, Volume 112 (2000), Edition 14, pp. 2625-2629.
  15. ↑ Michael Sinnott: Carbohydrate Chemistry and Biochemistry. Royal Society of Chemistry, 2013, ISBN 978-1-782-62632-9 . Pp. 721, 722.