[Photochemical affinity labeling of the macrolide binding site on the 70S E. coli ribosome]

Photoactivation of the alpha, beta-unsaturated ketone-epoxide system of [3H] dihydrorosaramycin at a wavelength above 300 nm allows the covalent attachment of the antibiotic to its receptor site. The radioactivity is mainly associated to proteins L1, L5, L6, S1; as a consequence, the binding site of this type of drug could be located at the peptidyltransferase center and in between both subunits.