5.7- Diamino-3,5,7,9-tetradeoxynonulosonic

The biosynthesis of Kdo and neuraminic acid is known to involve enol-pyruvate phosphate and D-arabinose or 2-acetamido-2-deoxy-D-mannose, respectively. Nothing is known about the biosynthesis of all the other glycu-losonic acids. One interesting problem is, for example, whether the two 5,7-diamino-3,5,7,9-tetradeoxynonulosonic acids are synthesized analogously to neuraminic acid, from a three- and a six-carbon fragment, by modification of neuraminic acid on the sugar nucleotide level, or by a third, less obvious route. 

Y. A. Knirel and N. K. Kochetkov, 2,3-Diamino-2,3-dideoxyuronic and 5,7-diamino-3,5,7,9-tetradeoxynonulosonic acids New components of bacterial polysaccharides, FEMS Microbiol. Rev., 46 (1987) 381-385. 

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