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

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.

Electron and ion spectroscopy of the cyclo-alanine–alanine dipeptide

“…The area of these fragments can finally be reported versus the binding energy, BE = hv − KE , see ref. 19 and Fig. 2 of the present paper where a larger set of fragments is shown.…”

“…While the pathways of formation and the reactivity of fragment 71 + have been already presented in a previous publication, 19 in the following we will discuss the general picture on cAA + molecular fragmentation. To this purpose, we have performed ab initio molecular dynamics (MD) simulations at two internal excitation energies, namely 10 and 15 eV.…”

“…Nevertheless, the driving force for the investigation of dipeptides spans from the need to answer fundamental questions concerning the origin of life 19,25 and the biological activities of larger peptides and proteins, 26 to their exploitation in therapeutic 27 and technological applications. 28–30…”

Prebiotic Membranes and Micelles Do Not Inhibit Peptide Formation During Dehydration

“…The presence of fatty acids does not have a significant effect on the yield of dipeptide after 6 hours of dehydration: in the absence of fatty acids, we estimate 11.5 % yield when the initial pH is 7 (Figure S12) compared to 12.0 % and 6.1 % in the presence of decanoic acid and heptanoic acid, respectively (Figure 4). Although our measurements do not distinguish linear and cyclic dipeptides, both compounds can elongate into growing peptide chains [36] . In our experiments, we detect very low yields (<1 %) of serine tripeptides (Figure S11).…”

“…Although our measurements do not distinguish linear and cyclic dipeptides, both compounds can elongate into growing peptide chains. [36] In our experiments, we detect very low yields (< 1 %) of serine tripeptides (Figure S11).…”