Purification, crystallization and preliminary X-ray diffraction analysis of S-formylglutathione hydrolase from Arabidopsis thaliana: effects of pressure and selenomethionine substitution on space-group changes.

S-Formylglutathione hydrolase (SFGH) has activity toward several xenobiotic carboxyesters and catalyses the final step of formaldehyde detoxification: the hydrolysis of S-formylglutathione to formate and glutathione. The Arabidopsis thaliana enzyme (AtSFGH) was crystallized in space group C2, with unit-cell parameters a = 128.5, b = 81.1, c = 94.3 A, beta = 93.3 degrees and three molecules in the asymmetric unit. A second crystal form of AtSFGH could be obtained by pressurizing the monoclinic crystals at 2 MPa for 30 min. The resulting space group is either P3(1)21 or P3(2)21, with unit-cell parameters a = 75.1, c = 92.8 A and one molecule in the asymmetric unit. Crystallographic data have been collected for both crystal forms to resolutions of 1.7 A for the monoclinic crystal and 1.6 A for the trigonal crystal. The structure has been solved by MAD phasing using a three-wavelength data set collected from a monoclinic crystal of selenomethionine-labelled AtSFGH.