Crystallization and preliminary crystallographic studies of five crystal forms of Escherichia coli L-asparaginase II (Asp90Glu mutant)

L-Asparaginase II from Escherichia coli with an Asp90Glu mutation in the active site has been crystallized in five polymorphic forms. Crystals of all polymorphs suitable for X-ray diffraction experiments were obtained by the vapour-diffusion method. Crystals of form I belong to the monoclinic system (space group C2), have unit-cell parameters a = 73.1, b = 133.1, c = 62.6 Å, β = 108.8° and diffract to 2.27 Å resolution. Three of the crystal forms are orthorhombic, with unit-cell parameters a = 225.4, b = 128.0, c = 62.6 Å (form II, P2₁2₁2), a = 59.9, b = 71.2, c = 130.6 Å (form III, primitive cell) and a = 73.8, b = 122.1, c = 124.2 Å (form IV, P2₁2₁2₁ or P2₁2₁2); the crystals diffract to 2.33, 3.5 and 1.7 Å, respectively. Polymorph V is trigonal, space group P3₁21, with unit-cell paramters a = 123.1, c = 83.8 Å; the crystals diffract to 2.65 Å resolution.