Protocell self-assembly driven by sodium trimetaphosphate.

Abstract

The co-evolution of peptide formation and membrane self-assembly is considered an essential step in the origin of life. In this study, we systematically investigated the sodium trimetaphosphate (P3m)-activated peptide formation reaction of Phe in an alkaline decanoic acid-decanol vesicle system. The experimental results showed that the peptide formation could competitively occur with N-acyl amino acid (NAA) formation. NAA formation did not follow the traditional P3m-activated peptide formation reaction involving the intermediate cyclic acylphosphoramidate (CAPA), but a phosphoric acid- decanoic acid mixed anhydride intermediate. NAA can form vesicles independently and reduce the critical vesicle concentration of the fatty-acid vesicles. 11 other representative amino acids, namely Ala, Asp, Glu, Gly, Ile, Leu, Pro, Ser, Thr, Val, and Arg, were selected for investigation. All of them reacted with decanoic acid to form NAA via the activation effect of P3m. Our experimental results indicate that the P3m activation effect can provide diversified raw membrane materials to form and stabilize protocell membranes; moreover, the small peptides, such as Phe-Leu, formed in the same reaction system can induce the amplification of primitive cells. This implies that synergistic symbiosis between membrane and peptide can be realized via the P3m activation effect.