UDP-N-acetylglucosamine

Formation of UDP-N-acetylglucosamine from N-acetylglucosamine 1-phosphate is catalyzed by a pyrophosphorylase which appears to be distinct from UDP-glucose pyrophosphorylase, but the reaction has not been studied in any detail. 

The transformations leading up to N-acetylglucosamine 1-phosphate are shown below. 

The information available concerning these reactions has recently been reviewed (see Davidson, 1966 Warren, 1966), and this discussion will therefore be limited to some recent work on glucosamine 6-phosphate formation. 

The synthesis of glucosamine 6-phosphate is of particular interest, since it is the first specific step in hexosamine formation. As seen above and from Fig. 8A, this process may be catalyzed by two different en- 

Reaction mechanisms for the two reactions have not yet been established, but it seems likely that the enediol form of fructose 6-phosphate is the intermediate reactant in the amidotransferase reaction. It has been suggested by Heyns and Paulsen (1960) that the deaminase reaction proceeds via enolization of a Schiffs base intermediate, as shown below. 

---

Stable and potent P2Y2 receptor agonists are being administered by inhalation as a potential treatment for cystic fibrosis. P2YH receptors are unusual in that they are activated by UDP-glucose, UDP galactose and UDP-N-acetylglucosamine [22],... 

Raetz, C. R., and Roderick, S. L. (1995). A left-handed parallel beta helix in the structure of UDP-N-acetylglucosamine acyl transferase. Science 270, 997-1000. 

No data are available regarding effects of competing enzymes on the activities of transferases other than glucuronyltransferase. For assays of native transglucuronylation rates, it may be useful to run parallel incubations with UDP-N-acetylglucosamine-fortified (SIO) and unfortified preparations, particularly when species are compared. 

Seppala R, Lehto VP, Gahl WA (1999) Mutations in the human UDP-N-acetylglucosamine... 

T Skarzynski, A Mistry, A Wonacott, SE Hutchinson, VA Kelly, K Duncan. Structure of UDP-N-acetylglucosamine enolpyruvyl transferase, an enzyme essential for the synthesis of bacterial peptidoglycan, complexed with substrate UDP-N-acetylglucosamine and the drug fosfomycin. Structure 4 1465-1474, 1996. 

M Crouvoisier, D Mengin-Lecreulx, J van Heijenoort. UDP-N-acetylglucosamine N-acetylmuramoyl-(pentapeptide) pyrophosphoryl undecaprenol N-acetylglucos-amine transferase from Escherichia coli. overproduction, solubilization, and purification. FEBS Lett 449 289-292, 1999. 

Figure 3 Schematic representation of the cytoplasmic steps of biosynthesis of UDP-N-acetylmuramic acid pentapeptide in E. coli. UDP-NAcGlc, UDP-N-acetylglucosamine PEP, phosphoenolpyruvate UDP-NAcEPGlc, UDP-N-acetylenolpyruvylglucosamine UDP-NAcMur, UDP-N-acetylmuramic acid meso-DAV, meso-diaminopimelic acid.

Sweet, C.R., Ribeiro, A.A., Raetz, C.R.H. Oxidation and transamination of the 3//-position of UDP-N-acetylglucosamine by enzymes from Acidithiobacillus ferrooxidans Role in the... 

Sweet, C.R., Williams, A.H., Karbarz, M.J., Werts, C., Kalb, S.R., Cotter, R.J., Raetz, C.R.H. Enzymatic synthesis of lipid A molecules with four amide-linked acyl chains LpxA acyltrans-ferases selective for an analog of UDP-N-acetylglucosamine in which an amine replaces the 3"-hydroxyl group. J Biol Chem 279 (2004b) 25411-25419. 

Mitsui, T., Tada, M., Nobusawa, C., and Yamaguchi, I., Inhibition of UDP-N-acetylglucosamine transport by diflubenzuron across biomembranes of the midgut epithelial cells in the cabbage army worm, Mamestra brassicae L., /. Pestic. Science, 10,55,1985. 

Tabata K, Koizumi S, Endo T, Ozaki A. Production of UDP-N-acetylglucosamine by coupling metabolically engineered bacteria. Biotechnol. Lett. 2000 22 479-483. 

Polyoxins are peptide-nucleosides that are substrate analogs of UDP-N-acetylglucosamine wliich is the essential building block of chitin, this polymer making up 1% of the yeast cell wall. Polyoxins have been used in agriculture for many years and act by inhibiting chitin synthetase. 

Kostrewa D, D Arcy A, Takacs B et al (2001) Crystal structures of Streptococcus pneumoniae N-acetylglucosamine-l-phosphate uridyltransferase, GlmU, in apo form at 2.33 A resolution and in complex with UDP-N-acetylglucosamine and Mg(2+) at 1.96 A resolution. J Mol Biol 305 279-289... 

UDP-N-acetylglucosamine- 2-epimerase none possible oxonium intermediate ... 

UDP-N-acetylglucosamine (UDP-GlcNAc) epimerase catalyzes a mechanistically exotic stereoinversion of UDP-GlcNAc to UDP-ManNAc, which is used in the synthesis of some bacterial cell walls [106, 107]. The epimerase has the unusual requirement for a small amount of substrate UDP-GlcNAc for activity (i.e., UDP-ManNAc and enzyme alone will not react). It is thought that UDP-GlcNAc may bind in a modulating site, separate from the active site [106]. 

---