Factor- and energy-free peptide synthesis promoted by aromatic tertiary amines including nucleic acid-related compounds

We have already reported a novel, in vitro translation system, promoted by pryidine instead of the usual protein factors and energy sources, which consists of only salt-washed ribosomes from Escherichia coli, aminoacyl-tRNA, a template RNA, Na⁺ and Mg²⁺ cations, and 4-60% pyridine [Nitta et al. (1994) J. Biochem. 115, 803-807 and the accompanying paper]. Here we show that in this system, pyridine can be replaced not only by pyridine derivatives but also by nucleobases or nucleosides, demonstrating that any compound harboring an aromatic tertiary amine within the molecule possesses such promoting activity. These compounds may serve to assist the peptide bond formation catalyzed by peptidyltransferase within ribosomes. The finding that nucleobases and nucleosides can play such a role in this reaction implies the possibility that these compounds were directly involved in the premordial translation system.