An antibiotic named fixmycin, which you have isolated from a fungus growing on ripe passion fruit, is effective in curing several types of sexually transmitted diseases. In characterizing fixmycin’s mode of action, you have found that it is a bacterial translational inhibitor that binds exclusively to the large subunit of E. coli ribosomes. The initiation of protein synthesis in the presence of fixmycin results in the generation of dipeptides that remain associated with the ribosome. Suggest a mechanism of fixmycin action.