The sedimentation behaviour of ribonuclease-active and -inactive ribosomes from bacteria.

摘要: 1. The `30s' and `50s' ribosomes from ribonuclease-active (Escherichia coli B) -inactive (Pseudomonas fluorescens Escherichia MRE600) bacteria have been studied in the ultracentrifuge. Charge anomalies were largely overcome by using sodium chloride–magnesium chloride solution, I 0·16, made 0–50mm with respect to Mg2+. 2. Differentiation of enzymic physical breakdown at Mg2+ concentrations less than 5mm was comparing properties E. B P. ribosomes. 3. Ribonuclease-active alone showed a transformation into 40–43s components. This combined release small amount `5s' material which may be covalently bound soluble RNA. Other transformations 34–37s components observed both 1·0–2·5mm-Mg2+, also MRE600 when EDTA (0·2mm) added solution 0·16m-sodium chloride. 4. Degradation concentration 0·25mm or coincident formation 16s 21s ribonucleoprotein fluorescens, this suggested that complete dissociation RNA protein not an essential prelude enzyme. 5. As high Cs+/Mg2+ ratios cause ribosomal degradation great care is necessary interpretation equilibrium-density-gradient experiments caesium similar salts are used. 6. importance moiety understanding response their ionic environment discussed.