Ester-Mediated Amide Bond Formation Driven by Wet–Dry Cycles: A Possible Path to Polypeptides on the Prebiotic Earth
Dr. Jay G. Forsythe1,2,‡, Sheng-Sheng Yu1,3,‡, Dr. Irena Mamajanov1,2, Prof. Martha A. Grover1,3, Prof. Ramanarayanan Krishnamurthy1,4,*, Prof. Facundo M. Fernández1,2,* andProf. Nicholas V. Hud1,2,*
Article first published online: 15 JUL 2015
†We thank D. Gaul, A. Petrov and F. J. Schork for discussions, and C. O'Mahony and A. Doody for use of a FTIR spectrometer. This work was supported by the NSF and the NASA Astrobiology Program under the NSF Center for Chemical Evolution [CHE-1004570].
chemical evolution; day–night cycle; depsipeptides; origins-of-life; proto-peptides
Although it is generally accepted that amino acids were present on the prebiotic Earth, the mechanism by which α-amino acids were condensed into polypeptides before the emergence of enzymes remains unsolved. Here, we demonstrate a prebiotically plausible mechanism for peptide (amide) bond formation that is enabled by α-hydroxy acids, which were likely present along with amino acids on the early Earth. Together, α-hydroxy acids and α-amino acids form depsipeptides—oligomers with a combination of ester and amide linkages—in model prebiotic reactions that are driven by wet–cool/dry–hot cycles. Through a combination of ester–amide bond exchange and ester bond hydrolysis, depsipeptides are enriched with amino acids over time. These results support a long-standing hypothesis that peptides might have arisen from ester-based precursors.
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