We demonstrate here that ribosomes from not only Escherichia coli and Thermus thermophilus [Nitta et al. (1994) J. Biochem. 115, 803-807; J. Biochem., (1995) 118, 841-849] but also yeast and bovine mitochondria catalyze peptide synthesis promoted by a high concentration of pyridine in the absence of soluble protein factors and chemical energy sources, and compare some characteristic features of the reactions among these organisms. Sensitivities against antibiotics, chloramphenicol and cycloheximide, showed the same tendency to those in the in vitro aqueous translation systems of these organisms, suggesting that the basic mechanism for peptide synthesis is the same among these organisms. The optimal concentration of pyridine was centered at 50% for all systems, although the dependencies on the pyridine concentrations and the yields of the products were different from one another. All these systems required Mg²⁺, and only mitochondrial system showed the extra Mn²⁺-requirement, which enhanced the yield by several fold. The optimum reaction temperatures coincided closely with the growing temperatures of the organisms except for the mitochondrial system, which showed the highest activity above 80°C. The rationale for these observations remains to be solved.