Crystallization and X-ray diffraction analysis of 6-­aminohexanoate-cyclic-dimer hydrolase from Arthrobacter sp. KI72

6-Aminohexanoate-cyclic-dimer hydrolase (EI) from Arthrobacter sp. KI72 was expressed in Escherichia coli and purified by anion-exchange chromatography. EI was crystallized by the sitting-drop vapour-diffusion method with sodium citrate as precipitant in imidazole buffer pH 8.0. The crystal is hexagonal, with unit-cell parameters a = b = 130.75, c = 58.23 Å. Diffraction data were collected from native and mercury(II) dichloride-derivative crystals to resolutions of 1.90 and 2.06 Å, respectively.