Expression, purification, crystallization and preliminary X-ray analysis of human argininosuccinic acid lyase

Human argininosuccinic acid lyase (ASAL) has been expressed, purified and crystallized in several distinct crystal morphologies. At present only one form is suitable for X-ray diffraction analysis. These crystals grow as hexagonal prisms, with unit cell dimensions a = b = 104.6 A, c = 185.3 A and alpha = beta = 90 degrees, gamma = 120 degrees. The crystals exhibit the symmetry of space group P3(1)21 or its enantiomorph, P3(2)21 (indistinguishable crystallographically) and diffract to a minimum d-spacing of approximately 3.5 A.