[Mechanism of codon-anticodon interaction in ribosomes. Interaction of aminoacyl-tRNA with 70S ribosomes in the absence of elongation factor EF-Tu and GTP]

Abstract

Purified Phe-tRNAPhe revealed higher affinity to the donor (D) site of vacant 70S . poly(U) complex than to the acceptor (A) site, independent on Mg2+ concentration. As a result, in excess of ribosomes Phe-tRNAPhe binds exclusively to the D site. This was proved using the tests in the presence of tetracycline and puromycin. Preferential binding of Phe-tRNAPhe to the D site was used to measure equilibrium association constants of this interaction at different temperatures and Mg2+ concentrations. A large value of reaction enthalpy (ca. -26 Kcal/mole) was found.