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

A duck delta II crystallin mutant, where histidine 178 has been replac ed by an aspartic acid residue, has been purified from a bacterial exp ression system and subsequently crystallized. The crystals grow as fla t plates, with unit cell dimensions a = 94.1 Angstrom, b = 99.9 Angstr om. c = 108.7 Angstrom and beta = 102 degrees. The crystals exhibit th e 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 mon omers (one tetramer) are estimated to be present in the asymmetric uni t (V-m = 2.5 Angstrom(3)/Da). Self-rotation functions clearly show the presence of 222 non-crystallographic symmetry.