293. Glycine peptides. Part II. The heat and entropy of formation of the peptide bond in polyglycine

An Evaluation of the Critical Parameters for Abiotic Peptide Synthesis in Submarine Hydrothermal Systems

“…Using the free energy of hydrolysis of a dipeptide of ∼ 3.6 kcal/mole (Meggy 1956;Martin 1998), equilibria for amino acid dimerization can be estimated between 10 −2 and 5×10 −2 M −1 between 100°C and 300°C. Using the free energy of hydrolysis of a tripeptide of ∼ 2.5 kcal/ mole (Martin 1998), equilibria for amino acid elongation can be estimated between 2 and 0.13 M −1 between 100°C and 300°C, assuming there is no degradation of monomer during the approach to equilibrium.…”

“…Based on what is known from physical organic chemistry this may be problematic. To form a peptide bond in water, considerable energy must be supplied (estimated as ∼ 2.5-3.6 kcal/ mole (Meggy 1956;Martin 1998), which could be provided by a high temperature environment. However, simultaneously competing hydrolytic decay of the reactant amino acids (White 1984) must be avoided.…”

Marine Hydrothermal Systems and the Origin of Life

“…Many of these experiments have been conducted at anhydrous conditions which strongly favor the dehydration reactions leading to peptide bond formation (Meggy, 1953(Meggy, , 1956Kovacs et aI., 1953;Kovacs and Konyers, 1954;Pavel, 1957a, 1957b;Fox et aI., 1957Fox et aI., , 1959Fox et aI., , 1963Harada, 1958, 1960;Harada and Fox, 1958, 1960Vegotsky et aI., 1958;Fox, 1963Fox, , 1964Fox, , 1965Rohlfing, 1967Rohlfing, , 1976Fox and Waehneldt, 1968;Rohlfing, 1972, 1974;Phillips and Melius, 1974;Snyder and Fox, 1975;Rohlfing and McAlhaney, 1976;Fouche and Rohlfing, 1976;Temussi et aI., 1976;Fox and Dose, 1977;Grote et aI., 1978;Kokufuta et aI., 1978;Lacey et aI., 1979;Harada and Matsuyama, 1979;Hartmann et aI., 1981;Fox and Nakashima, 1981; among others). None of these results can be applied directly to hydrothermal systems because of the anhydrous nature of the experiments.…”

keV ion irradiation assisted prebiotic synthesis of oligopeptide in the solar system

“…The general problem of peptide formation from amino acids is the thermodynamically and kinetically unfavorable process of dehydration (Meggy, 1956). To overcome the thermodynamic barrier, a variety of catalysts and external energy are necessary: a catalyst can decrease the activation energy of chemical reaction and the external energy may promote cross-condensation or self-condensation reaction of amino acids.…”