RESUMO
Crystals of various ribosomal particles, diffracting best to 2.9 A resolution were grown. Crystallographic data were collected from shock frozen crystals with intense synchrotron radiation at cryo temperature. For obtaining phase information, monofunctional reagents were prepared from an undecagold and a tetrairidium cluster, by attaching to them chemically reactive handles, specific for sulfhydryl moieties. Heavy-atom derivatives were prepared by a specific and quantitative binding of the undecagold cluster to an exposed sulfhydryl prior to the crystallization. To create potential binding sites on the halophilic and thermophilic ribosomal particles, which yield our best and most interesting crystals, exposed reactive moieties were inserted, using genetic and chemical procedures. In order to choose the appropriate locations for these insertions, the surfaces of the ribosomal particles were mapped by direct chemical determination of exposed amino and sulfhydryl groups.
Assuntos
Bactérias/ultraestrutura , Cristalografia por Raios X/métodos , Ribossomos/ultraestrutura , DNA Complementar , Escherichia coli/ultraestrutura , Congelamento , Geobacillus stearothermophilus/ultraestrutura , Halobacteriaceae/ultraestrutura , RNA Ribossômico/ultraestrutura , Thermus thermophilus/ultraestruturaRESUMO
Hemangioendothelioma of the liver and spleen with similar affection of the organs resembling a bloody sponge was diagnosed histologically in men of 35 and 59 years. Microscopically, the structure of the tumour presented a picture of multiple ugly vascular fissures and cavities lined with atypical polymorphous endothelial cells not infrequently transformed into giant cells with hyperchronic nuclei. Impregnation of the sections with silver nitrate according to Gomori revealed an irregular vascular network and facilitated the recognition of the true nature of the disease.
