Crystallization and preliminary X-ray diffraction analysis of malic enzymefrom pigeon liver

Recombinant pigeon-liver malic enzyme was expressed in Escherichia coli and purified to homogeneity. Two different crystal forms were grown by the han ging-drop vapour-diffusion method. Both types of crystals belong to the tet ragonal space group P4(2)22, with unit-cell dimensions a = b = 163.8, c = 1 74.3 Angstrom for the octahedral crystals and a = b = 124.5, c = 179.2 Angs trom for the rod-like crystals. X-ray diffraction data were collected at 10 0 K using a synchrotron-radiation X-ray source. The Matthews parameter sugg ests that there are four and two molecules per asymmetric unit for the larg er and the smaller tetragonal unit cells, respectively.