title: Structure determination of a cocaine hydrolytic antibody from a pseudomerohedrally twinned crystal.
abstract: Few examples of pseudomerohedrally twinned macromolecular crystals have been described in the literature. This unusual phenomenon arises when a fortuitous unit-cell geometry makes it possible for twinning to occur in a space group that ordinarily does not allow twinning. Here, the crystallization, structure determination and refinement of the cocaine hydrolytic antibody 15A10 at 2.35 A resolution are described. The crystal belongs to space group P2(1), with two molecules in the asymmetric unit and unit-cell parameters a = 37.5, b = 108.4, c = 111.3 A and beta fortuitously near 90 degrees; the refined twinning fraction is alpha = 0.43. Interestingly, the non-crystallographic symmetry (NCS) and twin operators are nearly parallel, which appears to be a relatively frequent situation in protein crystals twinned by merohedry or pseudomerohedry.
authors.affiliation: The Department of Molecular Biology and Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, California, USA.
authors.forename: Nicholas A
authors.initials: NA
authors.lastname: Larsen
authors.forename: Andreas
authors.initials: A
authors.lastname: Heine
authors.forename: Paloma
authors.initials: P
authors.lastname: de Prada
authors.forename: El-Rashdy
authors.initials: el-R
authors.lastname: Redwan
authors.forename: Todd O
authors.initials: TO
authors.lastname: Yeates
authors.forename: Donald W
authors.initials: DW
authors.lastname: Landry
authors.forename: Ian A
authors.initials: IA
authors.lastname: Wilson
mesh_terms: D000906:Antibodies / Q000737:chemistry* / Q000276:immunology; D003042:Cocaine / Q000276:immunology / Q000378:metabolism*; D006868:Hydrolysis; D011487:Protein Conformation
chemical_list: D000906:Antibodies; D003042:Cocaine