Escherichia coli elongation factor Tu-GDP (EF-Tu-GDP) was crystallized in the presence of novel inhibitors. The only crystals which could be grown were epitaxially as well as merohedrally twinned, highly mosaic and diffracted to a resolution of 3.4 A in space group P3(1)21, with unit-cell parameters a = b = 69.55, c = 169.44 A, alpha = beta = 90, gamma = 120 degrees . To determine whether an inhibitor was present in the crystal, a poor-quality X-ray diffraction data set had to be processed. The three-dimensional structure was ultimately solved and the original question answered. The results also reveal a new type of dimer packing for EF-Tu-GDP.
The first polygalacturonase from a plant, tomato fruit PG2, has been crystallized and data have been collected to a resolution of 1.87 A. The autoindexing program strongly favors one of the primitive orthorhombic cells. A plausible molecular-replacement solution for two molecules in the asymmetric unit has been found for data assigned to space group P2(1)2(1)2(1). Although the numerical criteria and the electron-density maps are reasonable for this solution, manually adjusted models do not refine to an R factor below 0.48. Visual inspection of hkl Bragg planes does not reveal a breakdown in mm symmetry. Nevertheless, the correct space group has been determined to be P2(1), with similar unit-cell parameters, a beta angle of 90.04 degrees and four molecules in the asymmetric unit. The R(sym) of 0.053 for data processed in P2(1)2(1)2(1) is very similar to the R(sym) of 0.047 for the same data processed in P2(1). Comparisons of the intermediate results using the P2(1)2(1)2(1) and P2(1) data sets are provided and the subtle indications of an initial erroneous space-group assignment are discussed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.