Cryocrystallography of ribosomal particles.

Crystals suitable for X-ray study have been prepared from biochemically active ribosome particles or their complexes with tRNA and polypeptide chains. At ambient temperature the useful lifetime of these crystals under synchrotron irradiation is limited to a few minutes. However, upon cooling to cryogenic temperatures around 85 K, the original resolution limit (up to 4.5 A) can be recorded and radiation damage is virtually eliminated. Hence it has become possible to collect a complete data set from one single crystal. Crystals were cooled as rapidly as possible, either in a cold gas stream, or by immersion in liquid propane. Before cooling crystals were transferred either to an inert hydrocarbon environment, or to solutions similar to the crystallizing ones but with a higher viscosity. In several cases soaking in a cryosolvent was required. Crystallographic data were collected with intense synchrotron radiation. Full data sets have been measured for native and derivatized crystals of 50S ribosomal subunits from H. marismortui as well as from their complexes with tRNA and nascent polypeptide chains, from the wild type and a mutant of 50S subunits from B. stearothermophilus, and from crystals of native and derivatized 30S ribosomal subunits from T. thermophilus.