1.1.1.325 | purified recombinant His-tagged wild-type and selenomethionine-substituted enzymes, hanging drop vapour diffusion method at 18°C, mixing of 0.004 ml of protein solution containing 10 mg/ml in 20 mM Tris-HCl, pH 8.0, by ultrafiltration, with 0.001 ml of reservoir solution containing 0.2 M MgCl2, 0.1 M Tris-HCl, pH 8.5, 34% PEG 400, and 0.2 M guanidine hydrochloride, screening and method optimization, crystals of the wild-type enzyme are soaked in reservoir solution containing 1 mM NADP+ and 1 mM sepiapterin or containing 1 mM NADP+ and 1 mM N-acetylserotonin, respectively, X-ray diffraction structure determination and analysis at 2.1 A resolution |