Reactivity of Alanylalanine Diastereoisomers in Neutral and Acid Aqueous Solutions: A Versatile Stereoselectivity

Raphaël Plasson, Maika Tsuji, Masazumi Kamata, Kouichi Asakura

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

A good comprehension of the reactivity of peptides in aqueous solution is fundamental in prebiotic chemistry, namely for understanding their stability and behavior in primitive oceans. Relying on the stereoselectivity of the involved reactions, there is a huge interest in amino acid derivatives for explaining the spontaneous emergence of homochirality on primitive Earth. The corresponding kinetic and thermodynamic parameters are however still poorly known in the literature. We studied the reactivity of alanylalanine in acidic to neutral conditions as a model system. The hydrolysis into amino acids, the epimerization of the N-terminal residue, and the cyclization into diketopiperazine could be successfully identified and studied. This kinetic investigation highlighted interesting behaviors. Complex mechanisms were observed in very acidic conditions. The relative kinetic stability of the diastereoisomers of the dipeptide is highly dependent of the pH, with the possibility to dynamically destabilize the thermodynamically more stable diastereoisomers. The existence of the cyclization of dipeptides adds complexity to the system. On one hand it brings additional stereoselectivities; on the other hand fast racemization of heterochiral dipeptides is obtained.

Original languageEnglish
Pages (from-to)413-435
Number of pages23
JournalOrigins of Life and Evolution of Biospheres
Volume41
Issue number5
DOIs
Publication statusPublished - 2011 Oct

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Keywords

  • APED model
  • Diketopiperazine
  • Homochirality
  • Kinetics
  • Oligopeptide

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Space and Planetary Science

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