Acetylglucosamine-6-phosphate

This enzyme [EC 2.7.1.59] catalyzes the phosphorylation by ATP of iV-acetylglucosamine to generate ADP and A-acetylglucosamine 6-phosphate. The bacterial enzyme is also reported to act on glucose as well. 

This enzyme catalyzes the epimerization at the 2-position of A-acetylglucosamine 6-phosphate. See also N-Acyl-glucosamine-6-phosphate 2-Epimerase... 

N-acetylglucosamine-6-phosphate deac lase (protein aizyme) Yamano 2000... 

Yamano, N. Higashida, N. En(k>, C. Sakata, N. Fujishima, S. Maruyama, A. Higashihara, T. (2000) Purification and charactaization of Y-acetylglucosamine-6-phosphate deacetylase from a psychrotrophic marine bacterium, Alteromonas species. Mar. Biotechnol., 2, 57-64. 

Weidanz, J.A. Campbell, R Moore, D. DeLucas, L.J. Roden, L. Thompson, J.N. Vezza, A.C. N-acetylglucosamine kinase and N-acetylglucosamine 6-phosphate deacetylase in normal human erythrocytes and Plasmodium falciparum. Br. J. Haematol., 95, 645-653 (1996)... 

Glucosamine is recovered as A -acetylglucosamine-6-phosphate and the reacetylation probably follows phosphorylation, as in the normal biosynthesis of A -acetylhexosamine phosphates from fructose-6-phosphate. In practice, most reclamation is probably at the level of liberated A/-acetylhexosamine, rather than hexosamine. 

A -Acetylglucosamine-6-phosphate is a precursor of A/-acetylgalactos-amine and, in animals, sialic acid, all of which tend to become labelled fairly quickly from glucosamine in many tissues. 

Of significance are D-glucosamine and D-mannosamine (Fig. 29). d-G1ucos-amine-6-phosphate is formed from fructose-6-phosphate by the pathway given in Fig. 32. It is subsequently transformed to iV-acetylglucosamine-6-phosphate and iV-acetylmuramic acid. Synthesis of D-glucosamine-6-phosphate includes an intramolecular oxidoreduction at positions 1 and 2 transforming the ketose to an aldose derivative. 

An acetylase catalyzes the conversion of glucos-amine-6-phosphate to acetylglucosamine-6-phosphate in the presence of acetyl-CoA. Although enzyme preparations from most sources use phosphorylated hexos-amine as a substrate, liver contains both N-glucos-amine-6-phosphate and N-glucosamine acylases. 

Another liver enzyme uses N-acetylglucosamine-6-phosphate as a substrate to yield N-acetylmannosa-mine-6-phosphate. An enzyme obtained from hog kidney converts free N-acetylglucosamine to N-acetyl-mannosamine. An N-acetylmannosamine kinase requiring magnesium and potassium for activity phos-phorylates N-acetylmannosamine to yield the N-ace-tylmannosamine-6-phosphate. ATP acts as phosphate donor. 

These reactions have been thoroughly reviewed elsewhere (see, e.g., Roseman, 1962 Jourdian and Roseman, 1963 Warren, 1966) and will not be discussed further. It may merely be mentioned diat an alternative route exists for the formation of N-acetylmannosamine 6-phosphate which consists of a direct epimerization of N-acetylglucosamine 6-phosphate. However, the enzyme catalyzing this conversion has not been detected in mammalian tissues and appears to be exclusively limited to microorganisms. 

N-acetylglucosamine-6-phosphate mutase 2.7.5.2 GlcNAc-6-P — — cytosol Reissig and Leloir 1966... 

Yadav, V., Panilaitis, B., Shi, H., Numuta, K., Lee, K., Kaplan, D.L., 2011. N-acetylglucosamine 6-phosphate deacetylase (nagA) is required for N-acetyl glucosamine assimilation in Gluconacetobacter xylinus. PloS One 6 (6), el8099. 

Leloir and Cardini (1956) first found an enzyme in pig kidney cortex which catalyzed the synthesis of glucosamine-6-phosphate. The equilibrium of the enzyme reaction is strongly in favor of deamination. However, Comb and Roseman (1958a) showed that by coupling to a second enzyme (acetylase) the reaction can be pulled in the direction of synthesis. This enzyme (deaminase) apparently is ubiquitous and is stimulated by the presence of A -acetylglucosamine-6-phosphate. 

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