From amino acid mixtures to peptides in liquid sulphur dioxide on early Earth

Abstract

The formation of peptide bonds is one of the most important biochemical reaction steps. Without the development of structurally and catalytically active polymers, there would be no life on our planet. However, the formation of large, complex oligomer systems is prevented by the high thermodynamic barrier of peptide condensation in aqueous solution. Liquid sulphur dioxide proves to be a superior alternative for copper-catalyzed peptide condensations. Compared to water, amino acids are activated in sulphur dioxide, leading to the incorporation of all 20 proteinogenic amino acids into proteins. Strikingly, even extremely low initial reactant concentrations of only 50 mM are sufficient for extensive peptide formation, yielding up to 2.9% of dialanine in 7 days. The reactions carried out at room temperature and the successful use of the Hadean mineral covellite (CuS) as a catalyst, suggest a volcanic environment for the formation of the peptide world on early Earth.

New Signatures of Bio-Molecular Complexity in the Hypervelocity Impact Ejecta of Icy Moon Analogues

“…Thus, the abiotic synthesis of peptides is an important step in the prebi-otic chemistry that led to the emergence of life on the primitive Earth. Various scenarios have been suggested on the synthesis of peptides on the prebiotic Earth, which include synthesis in hydrothermal vents and dehydrating condition under dry and wet cycles [54]; synthesis triggers by activating agents [55,56]; presence of mineral catalysis [57,58], high energy protons and UV irradiation [59,60]; volcanic environment [37] and mechanochemical synthesis [50]. However, long polypeptide chains, as found in the present investigation, has not been reported before.…”

“…Though glycine was perhaps the major product in a prebiotic scenario, the significance of other amino acids cannot be neglected [35]. Further experiments were performed with the mixture of the two amino acids, which is a more realistic scenario for the prebiotic chemistry where interaction among different amino acids occurred [36,37]. The concentration of amino acids used in the present investigation is unusually high compared to the meteoritic abundance or any plausible prebiotic scenario.…”

Phosphorylation in liquid sulphur dioxide under prebiotically plausible conditions

“…1b). Urea is prebiotically plausible and well known to promote phosphorylation and other condensation reactions 16,19,51,56 . Discussed enhancement mechanisms involve urea hydrolysis and formation of activated intermediate carbamoyl phosphate and phosphor amidate species 16,19,48,57 .…”

“…However, the effect has not been described for solutions of liquid SO 2 yet. Previous peptide formations in this reaction medium required the presence of a metal 51 . In analogy to a proposed mechanism for amino acid condensation enhanced by trimetaphosphate, we suggest the formation of a cyclic intermediate ( 3) by intramolecular condensation of 2 prior to the nucleophilic attack of a second Ser unit and concomitant ring opening which leads to 4 (Fig.…”

“…CE-MS analyses were performed on an Agilent CE 7100 which was coupled to a Thermo Scienti c Orbitrap Q Exactive Plus mass spectrometer. The customized sheath-ow interface is described elsewhere 51 . Samples were diluted to a nucleoside concentration of 5 mM referring to the initial amount of one nucleoside.…”