Crystallization and preliminary X-ray study of saporin, a Ribosome Inactivating Protein from Saponaria officinalis

Single crystals of the protein saporin isolated from the seeds of S. officinalis have been grown by the vapor-diffusion method using ammonium sulfate as precipitant. The crystals are tetragonal, space group P4(1)22 (P4(3)22), with cell-dimensions a = b = 67.53 and c = 119.67 Angstrom, and diffract to 2.0 Angstrom resolution on a rotating-anode X-ray source. The asymmetric unit contains one molecule, corresponding to a volume of the asymmetric unit per unit mass (V-m) of 2.38 Angstrom(3) Da(-1).