Purification, crystallization and preliminary X-ray crystallographic analysis of ATP-phosphoribosyltransferase from Escherichia coli

ATP-phosphoribosyltransferase (ATP-PRT) from Escherichia coli has been puri fied and crystals were obtained by the vapour-diffusion method using sodium tartrate as a precipitant. Dynamic light scattering was used to assess con ditions for the monodispersity of the enzyme. The crystals are trigonal, sp ace group R32, with unit-cell parameters a = b = 133.6, c = 114.1 Angstrom (at 100 K), and diffract to 2.7 Angstrom on a synchrotron X-ray source. The asymmetric unit is likely to contain one molecule, corresponding to a pack ing density of 2.9 Angstrom (3) Da(-1). A model for the quaternary structur e is proposed based on the crystallographic symmetry.