title: Crystallization and preliminary X-ray diffraction analysis of restriction endonuclease EcoRII.
abstract: Crystals of the restriction endonuclease EcoRII have been obtained by the vapor-diffusion technique in the presence of ammonium sulfate or polyethylene glycol. The best crystals were grown with ammonium sulfate as a precipitant. Crystals with dimensions of up to 0.6 x 0. 6 x 0.6 mm have been observed. The crystals diffract to about 4.0 A resolution at a cryo-temperature of 100 K using a rotating-anode X-ray source and a Rigaku R-AXIS IV imaging-plate detector. The space group has been determined to be either I23 or I2(1)3, with unit-cell parameters a = b = c = 160.3 A, alpha = beta = gamma = 90 degrees. The crystal asymmetric unit contains two protein molecules, and self-rotation function analysis shows a pseudo-twofold symmetry relating the two monomers. Attempts to improve the resolution of crystal diffraction and to search for heavy-atom derivatives are under way.
authors.affiliation: NASA Marshall Space Flight Center, Huntsville, AL 35812, USA.
authors.forename: E A
authors.initials: EA
authors.lastname: Karpova
authors.forename: E
authors.initials: E
authors.lastname: Meehan
authors.forename: M L
authors.initials: ML
authors.lastname: Pusey
authors.forename: L
authors.initials: L
authors.lastname: Chen
mesh_terms: D000645:Ammonium Sulfate; D011232:Chemical Precipitation; D003460:Crystallization; D015252:Deoxyribonucleases, Type II Site-Specific / Q000737:chemistry*; D004058:Diffusion; D008970:Molecular Weight; D011092:Polyethylene Glycols; D014835:Volatilization; D014961:X-Ray Diffraction
chemical_list: D011092:Polyethylene Glycols; C046545:CCWGG-specific type II deoxyribonucleases; D015252:Deoxyribonucleases, Type II Site-Specific; D000645:Ammonium Sulfate