Properties of ribonucleoprotein particles in chloramphenicol-treated cells of Escherichia coli B

Abstract 1. 1. The electrophoretic pattern of proteins isolated from chloramphenicol particles has been examined by polyacrilamide-gel electrophoresis and compared with that obtained with ribosomal proteins. All proteins isolated from chloramphenicol particles, with the exception of two or three in the upper part of the gel, behave like ribosomal proteins on electrophoresis. 2. 2. The sedimentation characteristics of ribonucleoprotein particles present in the cell before chloramphenicol addition have been examined after the addition of antibiotic to the culture. After 15–30 min of incubation in the presence of chloramphenicol, there is a pronounced decrease in the amount of preexisting 50- and 30-S subunits, and chloramphenicol particles containing RNA synthesized before chloramphenicol addition, appear.