Magnesium ion dependence of free and polysomal ribosomes from Escherichia coli

Eliora Z. Ron*, Robert E. Kohler, Bernard D. Davis

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


This paper presents a simple means of distinguishing two kinds of 70 s ribosomes from Escherichia coli: intact complexes with mRNA and peptidyl-tRNA, obtained by ribonuclease treatment of polysomes; and free ribosomes, relieved of the polypeptide (and presumably of tRNA and mRNA) by treatment with puromycin in vitro. Free ribosomes are completely dissociated into subunits at 1 to 2 mm-Mg2+, while preparations containing polysomal ribosomes are only partly dissociated. Evidence obtained by the application of this criterion supports the conclusion, presented in the preceding paper, that the cell normally contains undissociated free ribosomes, and that their concentration increases when the products of polysomes runoff are caused to accumulate.

Original languageEnglish
Pages (from-to)83-89
Number of pages7
JournalJournal of Molecular Biology
Issue number1
StatePublished - 28 Aug 1968
Externally publishedYes


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