ManNAc kinase

N-acetylmannosamine kinase N-acyl-D-mannosamine kinase UDP-GlcNAc-epimerase/ManNAc kinase <2-4> [8-13] acetylamidodeoxymannokinase acetylmannosamine kinase acylaminodeoxymannokinase acylmannosamine kinase acylmannosamine kinase (phosphorylating)... 

NaCl <4> (<4> ManNAc kinase activity is increased by presence of 200 mM... 

Figure 11.1 The sialic acid biosynthetic pathway. Sialic acid biosynthesis occurs within the cytosol and is governed by the bifunctional enzyme GNB, which has two domains that possess enzymatic activities UDP-GlcNAc 2-epimerase and ManNAc kinase. Synthesis starts with the epimerization of UDP-GlcNAc to ManNAc by UDP-GlcNAc 2-epimerase after the release of UDP in a two-stage process. Phosphorylation of ManNAc is catalyzed by ManNAc kinase, but in some hyposialylated cells this canbe done by GlcNAc kinase. Subsequent steps lead to formation of free...

Figure 11.3 Incorporation of exogenous sialic acid metabolites into the pathway for sialic acid synthesis. Mutations in the GNE gene cause reduced GlcNAc epimerase and ManNAc kinase enzymatic activities, which can be rescued by supplementation with sialic acid metabolites. ManNAc or NeuAc can be incorporated...

Penner J, Mantey LR, Elgavish S et al. (2006) Influence of UDP-GlcNAc 2-Epimerase/ManNAc kinase mutant proteins on hereditary inclusion body myopathy. Biochemistry AS, 2968-2977. 

Kurochkina N, Yardeni T, Huizing M. (2010) Molecular modeling of the bifunctional enzyme UDP-GlcNAc 2-epimerase/ManNAc kinase and predictions of structural effeds of mutations assodated with HIBM and sialuria. Glycobiology 20, 322-337. 

Oetke C, Hinderlich S, Reutter W, Pawlita M. (2003) Bpigenetically mediated loss of UDP-GlcNAc 2-epim-erase/ManNAc kinase expression in hyposialylated cell lines. Biochem Biophys Res Commun 308, 892-898. 

GlcNAc/ManNAc kinase present in many tissues... 

This topic may be physiologically very important, but it is not well understood. A human genetic disorder called sialuria shows the importance of at least one prediction from in vitro studies. In this condition, large amounts of sialic acid (5-7 g/day) are secreted into the urine along with various intermediates in the UDP-GlcNAc--->CMP-Sia pathway [86, 87]. This was confirmed to be due to a defective feed-back inhibition of the 2-epimerase/ManNAc kinase, the first step in the pathway [88]. 

In this one-pot procedure NeuAc 16 is generated from ManNAc 15 and pyruvic acid in situ with sialic acid aldolase and then converted irreversibly to CMP-NeuAc 17. CMP is converted to CDP with myokinase and ATP. The released ADP is converted to ATP with pyruvate kinase and PEP. CDP is then converted to CTP also with pyruvate kinase and phosphoenolpyruvate (PEP). The formed CTP reacts with NeuAc catalyzed by NeuAc synthetase to give 17. 

To HEPES buffer (100 mL, 200 mM, pH 7.5) were added ManNAc 15 (1.44 g, 6 mmol), PEP sodium salt (1.88 g, 8 mmol), pyruvic acid sodium salt (1.32 g, 12 mmol), CMP (0.64 g, 2 mmol), ATP (11 mg, 0.02 mmol), pyruvate kinase (300 U), myokinase (750 U), inorganic pyrophosphatase (3 U), /V-acctylneuraminic acid aldolase (100 U), and CMP-sialic acid synthetase (1.6 U). The reaction mixture was stirred at room temperature for 2 days under argon, until CMP was consumed. The reaction mixture was concentrated by lyophilization and directly applied to a Bio-Gel P-2 column (200-400 mesh, 3 x 90 cm), and eluted with water at a flow rate of 9 mL/h at 4°C. The CMP-NeuAc fractions were pooled, applied to Dowex-1 (formate form), and eluted with an ammonium bicarbonate gradient (0.1-0.5 M). The CMP-NeuAc fractions free of the nucleotides were pooled and lyophilized. Excess ammonium bicarbonate was removed by addition of Dowex 50W-X8 (H+ form) to the stirred solution of the residual powder until pH 7.5. The resin was filtered off and the filtrate was lyophilized to yield the ammonium salt of CMP-NeuAc 17 (1.28 g, 88%). 

GNE UDP-GlcNAc 2-epimerase/ManNAc 6-kinase GDP guanidine diphosphate hEBD human embryoid body-derived... 

Figure 10 The sialoside biosynthetic pathway in eukaryotic cells A, UDP-GlcNAc-2-epimerase B, ManNAc-6-kinase C, Neu5Ac-9-P04 synthase D, NeuSAc-b-POj phosphatase E, CMP-Neu5Ac-synthetase F, sialyltransferase. Enzymes A and B function together as a bifunctional enzyme.

Wang Z, Sun Z, Li AV, Yarema KJ. (2006) Roles for UDP-GlcNAc 2-epimerase/ManNAc 6-kinase outside of sialic add biosynthesis modulation of sialyltrans-ferase and BiP expression, GM3 and GD 3 biosynthesis, proliferation, and apoptosis, and ERKl/2 phosphorylation. JEM Chem 281(37), 27016-27028. 

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