Preliminary crystallization and X-ray analysis of orthorhombic human endothelin

Human endothelin (ET-1) is a highly potent, ubiquitous, endogenous 21 amino acid residue polypeptide, which acts as a vaso- and bronchoconstrictor. Crystals of the active, uncomplexed form of ET-1 have been grown from aqueous solutions. These crystals, which are long hexagonal prisms, diffract to 2.98 A and are apparently of the space group P222(1) with cell dimensions a = 33.5 A, b = 57.9 A, c = 59.6 A. The six molecules in the asymmetric unit are related by non-crystallographic symmetry operations, which result in a pseudo 6(1) appearance to the data.