title: The use of pseudosymmetry in the rotation function of gamma IVa-crystallin.
abstract: Bovine lens gamma IVa-crystallin crystallizes in space group C222(1) with cell dimensions a = 35.1, b = 46.2, c = 186.2 A, and contains one molecule in the asymmetric unit. The structure was determined at 3.0 A resolution using cross-rotation functions and R-factor searches with the bovine lens protein gamma II-crystallin as the model structure. The rotation function appears to be very sensitive to the resolution range and type of coefficient employed; the use of normalized structure-factor amplitudes gave the best results. The potential problem of a pseudo solution due to an internal pseudo-twofold axis was put to advantage by aligning this axis parallel to z. The results of the R-factor search were well defined. The molecular replacement solution was improved by rigid-body least-squares refinement, initially of the whole molecule, then for the two domains. The R factor at this stage was 39.4% at 2.3-10.0 A. The gamma IVa structure has an even higher internal symmetry than gamma II, since the two domains are related by a rotation around the pseudo-twofold axis of 178.7 degrees as compared with 176.2 degrees for gamma II.
authors.affiliation: Department of Crystallography, Birkbeck College, London, England.
authors.forename: H E
authors.initials: HE
authors.lastname: White
authors.forename: H P
authors.initials: HP
authors.lastname: Driessen
authors.forename: C
authors.initials: C
authors.lastname: Slingsby
authors.forename: D S
authors.initials: DS
authors.lastname: Moss
authors.forename: W G
authors.initials: WG
authors.lastname: Turnell
authors.forename: P F
authors.initials: PF
authors.lastname: Lindley
mesh_terms: D000818:Animals; D002417:Cattle; D003459:Crystallins / Q000648:ultrastructure*; D011487:Protein Conformation; D014961:X-Ray Diffraction / Q000379:methods*
chemical_list: D003459:Crystallins