PROTEIN SYNTHESIS WITH ESCHERICHIA-COLI RIBOSOMES ALTERED IN CONFORMATION BY MONOVALENT CATIONS

When a mixture of 50 and 30 s ribosomal subunits of Escherichia coli was dialyzed against 1 m-ammonium chloride or 1 m-sodium chloride, the subunits were converted to particles with sedimentation coefficients of 25 and 15 s in the presence of 10-4 m-magnesium. On the other hand, after dialysis against 1 m-potassium chloride or 1 m-lithium chloride, the subunits were converted to 10 s particles. The altered ribosomes of type-I (25 and 15 s particles) were reconverted to 50 and 30 s particles when 10-2 m-magnesium was added, but could not be converted to 70 s particles. The altered ribosomes of type-II (10 s particles) were not reconverted to 50 and 30 s particles even in the presence of 10-2 m-magnesium but remained as 10 s particles. The altered ribosomes of type-I were considerably more active than normal ribosomes in f2 RNA-dependent polypeptide synthesis even in the absence of 70 s particles, while those of type-II did not participate in f2 RNA-dependent polypeptide synthesis. © 1969.