Purification, crystallization and preliminary X-ray diffraction data from selenomethionine glycinamide ribonucleotide synthetase

In this study. the overexpression, purification and crystallization of sele nomethionine (SeMet) incorporated glycinamide ribonucleotide synthetase (GA R-syn) from Escherichia coli are reported. The overexpression of Se let GAR -syn was placed under the control of the isopropylthio-beta-galactoside (IP TG) inducible T7 RNA-polymerase system. The newly developed construct conta ined a removable histidine tag an the amino terminus of GAR-syn, which allo wed rapid purification using metal-chelate chromatography techniques. The S eMet GAR-syn crystals were grown by hanging-drop vapor diffusion and belong to the space group P2(1)2(1)2(1) with unit-cell parameters a = 56.2, b = 6 2.4 and c = 129.8 Angstrom and a single monomer in the asymmetric unit. The crystals diffract to 1.6 Angstrom resolution and have led to the determina tion of multiple-wavelength anomalous diffraction phases to 2.2 Angstrom re solution.