Use of flow field-flow fractionation for the rapid quantitation of ribosome and ribosomal subunits in Escherichia coli at different protein production conditions.

Asymmetrical flow field-flow fractionation was used for rapid (8-14 min) separation of ribosomes and their subunits. The amount of ribosomes and the mass fraction of ribosomes was determined in growing Escherichia coli cells. These quantities changed significantly at different growth phases. Ribosomal composition was monitored after the insertion of a protein-encoding plasmid and after the addition of an antibiotic agent. The results suggest that the method will be useful in studies of, e.g., the relationships between the protein production capacity of cells and the ribosomal composition. The analysis time is substantially shorter than ultracentrifugation run times.