A model for protein synthesis involving the intermediate formation of peptidyl-5S RNA.

A model for protein synthesis is proposed in which the donor for the peptide elongation reaction is peptidyl-5S RNA. Space-filling models show that peptide bond formation between peptidyl-5S RNA and aminoacyl-tRNA is eminently feasible from a stereochemical point of view. The peptide is transferred to 5S RNA, while at the same time the deacylated tRNA is exchanged by a new aminoacyl-tRNA acceptor. Two peptidyl transferases are required by the model, both of which have sites for binding the termini of both aminoacyl-tRNA and peptidyl-5S RNA. The model makes detailed predictions about the properties of the transferases.