Characterization of single crystals of the large ribosomal particles from Bacillus stearothermophilus

Abstract Single, three-dimensional crystals of the 50 S ribosonial subunit from Bacillus stearothermophilus (strain NCA) have been characterized using a synchrotron X-ray source. The crystals are orthorhombic with unit cell dimensions: a = 350 A , b = 670 A , c = 905 A , and contain at least one 2-fold screw axis. With cooling to −2 °C, the large crystals (1.0 mm × 0.2 mm × 0.1 mm) diffract to 15 to 18 A resolution and are stable in the synchrotron beam for several hours. Despite the large cell dimensions, the reflections are readily resolved when the X-ray diffraction patterns are densitometered with a 25 μm raster.