Preliminary crystallographic investigations of glycinamide ribonucleotide transformylase

Crystals of glycinamide ribonucleotide transformylase have been grown from 0.4 to 1 M ammonium sulfate, 0.6 to 1 M sodium-potassium phosphate, or 0.65 to 1 M citrate in the pH range 4.5-7.0. The single crystals display variable morphology with varying pH. The crystals belong to the orthorhombic space group C222 with cell dimensions a = 141.4 Å, b = 98.2 Å, c = 103.5 Å. Co-crystals have also been obtained in the presence of the inhibitor 5,8-dideazafolate (K(i) = 18 μM) under similar crystallization conditions. Crystals of a chemically modified enzyme, iodinated at Cys-21, were grown under similar conditions within the pH range 6.5-7.0. These crystals are isomorphous with the unmodified enzyme. Crystals suitable for high resolution (<2.5 Å) x-ray diffraction studies have been obtained for each of the above.