Open AccessIonic Effects on the Ribosomal Quaternary Structure
Author(s) -
Ghysen A.,
Bollen A.,
Herzog A.
Publication year - 1970
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1970.tb00908.x
Subject(s) - ribosome , ribosomal rna , ribosomal protein , ultracentrifuge , divalent , chemistry , crystallography , ionic strength , escherichia coli , ionic bonding , protein quaternary structure , 50s , biophysics , biochemistry , ion , biology , rna , protein subunit , organic chemistry , aqueous solution , gene
Escherichia coli ribosomes, in various ionic conditions, were examined by ultracentrifugation analysis and melting studies. It has been shown that:1 The Tris ion acts as a monovalent cation and is indistinguishable from the potassium ion as far as its influence on the stability of the ribosome is concerned. 2 The ribosomal stability, as measured by the melting temperature ( T m ), and the ribosomal conformation, as observed by ultracentrifugation analysis, are only dependent on R , the ratio of the mono to the divalent ions concentrations. 3 The evolution of the ribosome as R increases is characterized by three phases: in the first one, the ribosome is in its most compact form (70 S); in the second one, the ribosomal subunits undergo a progressive loosening; and in the third, they are subject to a stepwise unfolding. 4 The hinge between the first and the second phases corresponds to the ionic conditions required for the correct functioning of the ribosomes in protein synthesis in vitro , and also for successful ribosomal reconstitutions.