Energetics of peptide bond formation at elevated temperatures.

The free energies of formation of the peptide bond between carbobenzoxy-glycine and L-phenylalanine amide in aqueous solution at temperatures up to 60 degree C were calculated from experimentally determined equilibrium constants. The reaction was catalyzed by a thermophylic enzyme. The thermodynamic energy barrier to peptide bond formation was found to decrease with increasing temperature: the standard free energy of peptide bond formation did appear to become negative in the region of 60 degrees C. The possible significance of these results for peptide bond formation under prebiotic conditions is discussed.