title: Crystallization of beta-galactosidase from Escherichia coli.
abstract: Two crystal forms of beta-galactosidase have been obtained from Escherichia coli. One crystal form is hexagonal space group P6222 or enantiomorph, with cell dimensions a = b = 154 A, c = 750 A. The second form is monoclinic, space group P21, with cell dimensions a = 107.9 A, b = 207.5 A, c = 509.9 A, beta = 94.7 degrees. The monoclinic form seems better suited to detailed structural analysis. The crystals are radiation-sensitive, but by using synchrotron radiation in conjunction with a long (400 mm) crystal-to-film distance it was possible to resolve the individual reflections. On the basis of crystal density measurements, there are four tetramers each of molecular weight 465,000 per asymmetric unit. The Patterson function strongly suggests that two of the tetramers are related to the other two by translation. The data are consistent with the tetramers having 222 point symmetry, but this is not proven.
authors.affiliation: Institute of Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene 97403.
authors.forename: R H
authors.initials: RH
authors.lastname: Jacobson
authors.forename: B W
authors.initials: BW
authors.lastname: Matthews
mesh_terms: D003461:Crystallography; D004926:Escherichia coli / Q000201:enzymology*; D011487:Protein Conformation; D014961:X-Ray Diffraction; D001616:beta-Galactosidase / Q000648:ultrastructure*
chemical_list: D001616:beta-Galactosidase