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Herriman, James (Teddy)

University of British Columbia

Water chemistry is as fundamental to life today as it is enigmatic to understanding pre-biotic chemistry and the emergence of life. While water is useful for diffusion in modern biology, among other beneficial features, pre-biotic polymers, such as peptides are susceptible to hydrolysis. Within the astrobiology field, peptide bond condensation is often taken for granted when compared to the study of amino acid generation and the function of peptides in bulk water. In particular, "Emergence of Life” research considering deep-sea hydrothermal vents often conflate dipeptide with polypeptide formation. Furthermore, computational chemists have generated models for peptide bond formation that do not replicate experimental observables of these reactions. Because of this, those looking to test the comparative plausibility of various Emergence of Life hypotheses – by way of peptide bond formation – do not have a theoretical foundation of ambient, bulk aqueous conditions for further chemical consideration. Here, as a first step in formulation of a “goldilocks zone” for peptide bond formation, a reaction mechanism for condensation of two glycine molecules and the hydrolysis of the simplest dipeptide glycylglycine was discovered using density functional theory. This six-step mechanism quantitatively reproduces the measured hydrolysis activation energy of 96 kJ molˉ¹ within 10 kJ molˉ¹ under ambient, physiologically relevant conditions. Further, the mechanism provides a plausible explanation for the equilibrium nature of dipeptide formation of amino acids observed so far in aqueous environments. This knowledge also has the potential to further our understanding of peptide regulation in extant biology and generate experimentally testable hypotheses for the critical assessment of “Metabolism First” proposal for the origins of the biosphere on Earth.

Text

2023-10-31

Attribution 4.0 International

http://hdl.handle.net/2429/86415

Chemistry

University of British Columbia

UBCO

http://creativecommons.org/licenses/by/4.0/