On the Phe-tRNA induced binding of fluorescent oligonucleotides to the ribosomal decoding site.

Fluorescent oligonucleotides were prepared by dansylation of 5'-amino uridylates of varying chainlength. Except for the trinucleoside diphosphate, they stimulated the binding of PhetRNA TO 70S E. coli ribosomes as efficiently as underivatised oligouridylic acids of comparable chainlength. The ternary ribosomal complex [70S X Phe-tRNA X dansyl-n5'U(pU)4] was separated from excess oligonucleotide and its fluorescence spectra were measured. The quantum yield of the dansylated pentauridylate was enhanced 2.5 fold when bound to the ribosomal decoding site, but no shift of the emission spectrum was observed. The ribosomal complex is considered useful for topographic investigations by singlet energy transfer, using the functionally defined decoding site as reference point.