CRYSTALLIZATION AND PRELIMINARY-X-RAY DIFFRACTION STUDIES ON THE APO FORM OF OROTATE PHOSPHORIBOSYLTRANSFERASE FROM ESCHERICHIA-COLI

Three different crystal forms of the apoenzyme orotate phosphoribosylt ransferase, with M(r)= 23,552 from Escherichia coli have been grown. T he crystals, which are all suitable for X-ray diffraction analysis, ha ve been grown by the hanging drop vapour diffusion method. The first f orm crystallizes in the orthorhombic space group P2(1)2(1)2, with cell dimensions: a = 136.34 Angstrom, b= 75.98 Angstrom and c = 40.32 a; t he second form in the monoclinic space group P2, with unit cell dimens ions: a = 101.61 Angstrom, b = 40.49 Angstrom, c = 79.05 Angstrom and beta = 87.33 degrees; and the third form in P2(1)2(1)2(1), the cell di mensions being a = 70.27 Angstrom, b = 103.53 Angstrom, c = 53.83 Angs trom.