CRYSTALLIZATION AND PRELIMINARY-X-RAY ANALYSIS OF A MUTANT DUCK DELTA-II-CRYSTALLIN

A duck delta II crystallin mutant, where histidine 178 has been replaced by an aspartic acid residue, has been purified from a bacterial expression system and subsequently crystallized. The crystals grow as flat plates, with unit cell dimensions a = 94.1 Angstrom, b = 99.9 Angstrom. c = 108.7 Angstrom and beta = 102 degrees. The crystals exhibit the symmetry of space group P2(1) and diffract to a minimum d-spacing of 2.8 Angstrom resolution. On the basis of density calculation four monomers (one tetramer) are estimated to be present in the asymmetric unit (V-m = 2.5 Angstrom(3)/Da). Self-rotation functions clearly show the presence of 222 non-crystallographic symmetry.