The effect of isolation conditions on the polyamine content of Escherichia coli ribosomes.

The polyamine content of isolated E. coli ribosomes is dependent on the nature and concentration of the ions in the medium used for their preparation. When ribosomes are suspended in medium containing amines, the external amines are taken up by the ribosomes. When large amounts of amines are taken up by the ribosomes, part of the original ribosomal amines are displaced into the medium. Magnesium ions have similar effects on the amine content of the ribosomes. These data indicate that quantitative determinations of the polyamine content of isolated ribosomes do not necessarily reflect the amine concentration of the ribosomes in vivo.