Crystallization and preliminary X-ray studies of methyl parathion hydrolase from Pseudomonas sp. WBC-3.

Methyl parathion hydrolase (MPH) from Pseudomonas sp. WBC-3, an enzyme that catalyzes the degradation of methyl parathion (O,O-dimethyl O-p-nitrophenyl phosphorothioate; MP), has been purified and crystallized by the hanging-drop vapour-diffusion method. The crystals were grown at 291 K using a precipitant solution consisting of 30% PEG 400, 0.1 M sodium acetate pH 4.6, 0.1 M CdCl(2). MPH is a zinc-containing enzyme judged by inductively coupled plasma mass-spectrometric (ICP-MS) analysis. Multiple-wavelength anomalous dispersive X-ray data were collected at 2.5 A resolution from a single crystal on beamline 41XU at SPring-8. The crystal belongs to space group P4(3)2(1)2, with unit-cell parameters a = 84.94, b = 84.94, c = 200.38 A, alpha = beta = gamma = 90 degrees. The asymmetric unit contains two molecules and has a solvent content of approximately 52%. Crystal structure determination is in progress.