2.7.1.162 purified recombinant His-tagged enzyme in complex with substrates GalNAc, GlcNAc-1P, GlcNAc/AMPPNP (a nonhydrolyzable ATP analogue) and GlcNAc-1P/ADP, hanging drop vapour diffusion method, pre-incubation of SeMet-substituted/wild-type NahK with GlcNAc (20fold excess), GalNAc (20fold excess) or GlcNAc-1P (10fold excess), and mixing of 20 mg/ml protein in 50 mM HEPES, pH 7.5, with a crystallization solution containing 20% w/v PEG 3350, 0.1 M Bis-Tris, pH 5.5, crystals of NahK-GlcNAc-AMPPNP are obtained by soaking NahK-GlcNAc crystals with 10 mM AMPPNP and 20 mM MgCl2 for 15 min, or the crystals of NahK-GlcNAc-1P-ADP by soaking NahK-GlcNAc-1P crystals with 5 mM ADP and 10 mM MgCl2 for 30 min, crystallization time is 10-14 days, 20°C, X-ray diffraction structure determination and analysis at 1.72-2.15 A resolution, molecular replacement method, modelling 2.7.1.162 purified recombinant His-tagged enzyme in complex with substrates GlcNAc, and GlcNAc/AMPPNP (a nonhydrolyzable ATP analogue), hanging drop vapour diffusion method, mixing of 20 mg/ml protein in 50 mM HEPES, pH 7.5, with crystallization solution containing 1.5 M Li2SO4, 0.1 M sodium acetate, pH 5.5, 2 days, crystals of the NahKATCC15697-GlcNAc-AMPPNP complex are obtained by soaking NahK-GlcNAc complex crystals with 5 mM AMPPNP and 10 mM MgCl2 for 1.5 h, 20°C, X-ray diffraction structure determination and analysis at 1.47-1.90 A resolution, molecular replacement method, modelling 2.7.1.162 purified recombinant wild-type enzyme in apoform, or SeMet-labeled NahK complexed with ATP, sitting drop vapor diffusion method, mixing of 500 nl protein solution containing 25 mg/mL NahK and with or without 10 mM ATP with an equal volume of reservoir solution containing 0.2 M magnesium acetate, 0.1 M sodium cacodylate, pH 6.5, and 20% PEG 8000, for ADP complex crystals, 10 mM ADP is used instead of ATP, 20°C, X-ray diffraction structure determination and analysis at 1.80-2.05 A resolution