An extended model for the evolution of prebiotic homochirality: A bottom-up approach to the origin of life

Marcelo Gleiser, Sara Imari Walker

Research output: Contribution to journalArticle

28 Scopus citations

Abstract

A generalized autocatalytic model for chiral polymerization is investigated in detail. Apart from enantiomeric cross-inhibition, the model allows for the autogenic (non-catalytic) formation of left and right-handed monomers from a substrate with reaction rates ε L and ε R , respectively. The spatiotemporal evolution of the net chiral asymmetry is studied for models with several values of the maximum polymer length, N. For N = 2, we study the validity of the adiabatic approximation often cited in the literature. We show that the approximation obtains the correct equilibrium values of the net chirality, but fails to reproduce the short time behavior. We show also that the autogenic term in the full N = 2 model behaves as a control parameter in a chiral symmetry-breaking phase transition leading to full homochirality from racemic initial conditions. We study the dynamics of the N→ ∞ model with symmetric (ε L = ε R ) autogenic formation, showing that it only achieves homochirality for ε > ε c , where ε c is an N-dependent critical value. For ε ≤ ε c we investigate the behavior of models with several values of N, showing that the net chiral asymmetry grows as tanh(N). We show that for a given symmetric autogenic reaction rate, the net chirality and the concentrations of chirally pure polymers increase with the maximum polymer length in the model. We briefly discuss the consequences of our results for the development of homochirality in prebiotic Earth and possible experimental verification of our findings.

Original languageEnglish (US)
Pages (from-to)293-315
Number of pages23
JournalOrigins of Life and Evolution of Biospheres
Volume38
Issue number4
DOIs
StatePublished - Aug 1 2008
Externally publishedYes

Keywords

  • Early planetary environments
  • Homochirality
  • Origin of life
  • Prebiotic chemistry

ASJC Scopus subject areas

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

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