[Interaction of dansyl-dipeptidyl-tRNA with E. coli ribosomes]

Dansyl-dipeptidyl-tRNA is found to bind with ribosomes in the presence of polyU much more efficiently than AcPhe-tRNA. 30-80% OF introduced danysl-dipeptidyl-tRNA is in a complex with ribosomes and reacts with puromycin in the presence of 5 mM Mg2+. A significant binding of dansyl-dipeptidyl-tRNA both for acceptor and donor ribosome regions is observed in the presence of 10 mMg2+, unlike AcPhe-tRNA, which is capable of the binding only at 20 mM Mg2+. A peptide transfer from dansyl-dipeptidyl-tRNA on puromycin takes place at 10 mM Mg2+ in the absence of template, while AcPhe-tRNA efficiently interacts with puromycin only at 20 mM Mg2+. The data obtained suggest that the increase of hydrophobity of a peptide residue in peptidyl-tRNA increases its binding in peptidyl transferase of ribosomes.