Activation and energy transfers supporting potential peptide protometabolisms at the origin of living systems: PeptiSystems

ANR PeptiSystemLife on Earth constitutes a historical process that developed by complexification starting from chemicalsystems. It is considered in this project that physico-chemical driving forces and contingency are responsibleof this process since its early beginning. Theoretical aspects will constitute both the starting point of thisproject and a matter of investigation to contribute to a better understanding of the physical origin ofcomplexity. Within this perspective, the emergence of protometabolisms defined as networks of chemicalreactions proceeding under far from equilibrium conditions and involving nonlinear features and thereforebeing capable of generating self-organisation (associated with a local decrease in entropy compensated bythe irreversibility of the overall process) is a key step for the origin of life. Chemical networks of this kindmust work as unidirectional sequences of reactions or preferably as unidirectional reaction cycles in which afurther process of positive chemical feedback would be capable of generating systems endowed withautocatalytic properties and then behaving in a nonlinear way. Determining which pathways could haveconstantly or repeatedly fed these systems with energy to maintain the far from equilibrium state is thenessential to understand how self-organisation could emerge. This approach is applied to the formation ofbiopolymers capable of functional activities that is generally considered as a prerequisite for the origin oflife. Our original goal is to propose an overall scenario integrating the formation of peptides and other relatedprocesses to build a network capable of giving rise to emergent properties related to the connections of thedifferent parts of the network. The project is aimed at understanding how peptides could be formed underprebiotic conditions and how energy sources could have been coupled to peptide bond formation. But it isnot limited to this goal since random peptides made from racemic mixtures of amino acids are unlikely toadopt definite structures needed for specific activity so that it will address the question of the emergence ofselectivity (and stereoselectivity) or that of improbable but dynamically stable states. Lastly the emergenceof translation at an early stage of evolution suggests that the chemistry of amino acids and peptides can becoupled to that of an information carrier supporting the hypothesis of a peptide-nucleotide co-evolution. Allthese topics will be experimentally investigated by monitoring the reactions through common methods ofanalytical chemistry and organic chemistry (NMR, HPLC, MS, UV…)