1.3.1.32 | purified recombinant His-tagged wild-type and SeMet-labeled PnpD, the sitting-drop vapour-diffusion method, 0.002 ml of 15 mg/ml protein in 20 mM Tris, pH 8.0, 5 mM NADH, and 20 mM NaCl are mixed with 0.002 ml of precipitant solution containing 0.2 M ammonium phosphate dibasic and 20% w/v PEG 3350, equilibration against 0.2 ml of reservoir solution, 20°C, X-ray diffraction structure determination and analysis at 2.9 A resolution |