Reaction: UDP-N-acetyl-α-D-glucosamine + H2O = N-acetyl-D-mannosamine + UDP
For diagram of reaction click here and mechanism click here.
Other name(s): UDP-N-acetylglucosamine 2-epimerase (ambiguous); GNE (gene name); siaA (gene name); neuC (gene name)
Systematic name: UDP-N-acetyl-α-D-glucosamine hydrolase (2-epimerising)
Comments: The enzyme is found in mammalian liver, as well as in some pathogenic bacteria including Neisseria meningitidis and Staphylococcus aureus. It catalyses the first step of sialic acid (N-acetylneuraminic acid) biosynthesis. The initial product formed is the α anomer, which rapidly mutarotates to a mixture of anomers . The mammalian enzyme is bifunctional and also catalyses EC 18.104.22.168, N-acetylmannosamine kinase. cf. EC 22.214.171.124, UDP-N-acetylglucosamine 2-epimerase (non-hydrolysing).
Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number:
1. Stasche, R., Hinderlich, S., Weise, C., Effertz, K., Lucka, L., Moormann, P. and Reutter, W. A bifunctional enzyme catalyzes the first two steps in N-acetylneuraminic acid biosynthesis of rat liver. Molecular cloning and functional expression of UDP-N-acetyl-glucosamine 2-epimerase/N-acetylmannosamine kinase. J. Biol. Chem. 272 (1997) 24319-24324. [PMID: 9305888]
2. Chou, W.K., Hinderlich, S., Reutter, W. and Tanner, M.E. Sialic acid biosynthesis: stereochemistry and mechanism of the reaction catalyzed by the mammalian UDP-N-acetylglucosamine 2-epimerase. J. Am. Chem. Soc. 125 (2003) 2455-2461. [PMID: 12603133]
3. Blume, A., Ghaderi, D., Liebich, V., Hinderlich, S., Donner, P., Reutter, W. and Lucka, L. UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase, functionally expressed in and purified from Escherichia coli, yeast, and insect cells. Protein Expr. Purif. 35 (2004) 387-396. [PMID: 15135418]
4. Murkin, A.S., Chou, W.K., Wakarchuk, W.W. and Tanner, M.E. Identification and mechanism of a bacterial hydrolyzing UDP-N-acetylglucosamine 2-epimerase. Biochemistry 43 (2004) 14290-14298. [PMID: 15518580]