"Smart Decomposition" of Cyclic Alanine-Alanine Dipeptide by VUV Radiation: A Seed for the Synthesis of Biologically Relevant Species.

Darío Barreiro-Lage,Henning Zettergren,Paola Bolognesi,Laura Carlini,Jacopo Chiarinelli,Sergio Diaz-Tendero,Robert Richter,Lorenzo Avaldi,Mark H Stockett

doi:10.1021/acs.jpclett.1c01788

Abstract

A combined experimental and theoretical study shows how the interaction of VUV radiation with cyclo-(alanine-alanine), one of the 2,5-diketopiperazines (DKPs), produces reactive oxazolidinone intermediates. The theoretical simulations reveal that the interaction of these intermediates with other neutral and charged fragments, released in the molecular decomposition, leads either to the reconstruction of the cyclic dipeptide or to the formation of longer linear peptide chains. These results may explain how DKPs could have, on one hand, survived hostile chemical environments and, on the other, provided the seed for amino acid polymerization. Shedding light on the mechanisms of production of such prebiotic building blocks is of paramount importance to understanding the abiotic synthesis of relevant biologically active compounds.

Highlights

A combined experimental and theoretical study shows how the interaction of VUV radiation with cyclo-(alanine-alanine), one of the 2,5-diketopiperazines (DKPs), produces reactive oxazolidinone intermediates
External agents are required in the absence of such activating reactants, and several mechanisms have been envisioned for the abiotic synthesis of proto-peptides, from thermal polymerization and wet−dry cycles to the intervention of condensing agents.[22,23]
These highly reactive intermediates, commonly used in modern laboratories for peptide synthesis,[38] could be formed and activated spontaneously without any catalyst or other reactive species, as we show in this work

Summary

Introduction

A combined experimental and theoretical study shows how the interaction of VUV radiation with cyclo-(alanine-alanine), one of the 2,5-diketopiperazines (DKPs), produces reactive oxazolidinone intermediates. Taking the lower-energy path initiated at the CO−CHCH3 bond break (blue path, TS1), we followed the evolution of linear structure Min[1] toward the production of the neutral and charged fragments with 71 amu (Figure 2d).

Results

Conclusion