Crystallization and a preliminary X-ray diffraction study of macrophage migration inhibitory factor from human lymphocytes.

Two crystal forms of the macrophage migration inhibitory factor (MIF) from human lymphocytes have been obtained by the hanging drop method of vapor diffusion from ammonium sulfate solution. A trigonal crystal form belongs to the space group P3(1)21 (P3(2)21), with unit cell dimensions of a = b = 96.4 A and c = 105.5 A. Assuming that the asymmetric unit contains two or three dimers, the Vm value is calculated as 2.9 or 1.9, respectively. A second crystal form is orthorhombic, space group P2(1)2(1)2(1) with unit cell dimensions a = 68.4 A, b = 68.8 A and c = 86.8 A. The Vm value is 2.1 for two dimers in the asymmetric unit. Both crystals diffract to at least 1.9 A and are suitable for X-ray crystallographic structure determination at a high resolution.