Life's chirality from prebiotic environments

Abstract

A key open question in the study of life is the origin of biomolecular homochirality: almost every life-form on Earth has exclusively levorotary amino acids and dextrorotary sugars. Will the same handedness be preferred if life is found elsewhere? We review some of the pertinent literature and discuss recent results suggesting that life's homochirality resulted from sequential chiral symmetry breaking triggered by environmental events. In one scenario, autocatalytic prebiotic reactions undergo stochastic fluctuations due to environmental disturbances. In another, chiral-selective polymerization reaction rates influenced by environmental effects lead to substantial chiral excess even in the absence of autocatalysis. Applying these arguments to other potentially life-bearing platforms has implications to the search for extraterrestrial life: we predict that a statistically representative sampling of extraterrestrial stereochemistry will be racemic (chirally neutral) on average.

Molecular Imprinting: The missing piece in the puzzle of abiogenesis?

“…Proposed mechanisms that might yield compounds in significant enantiomeric excess (e.g., differential photolysis by circularly polarized starlight [DMMN + 11], the growth and dissolution of chiral crystals [NIM + 08], or hypothetical autocatalytic cycles [GW12]) are of dubious prebiotic realism [ÁBC + 10], while prebiotic sources of diverse, substantially homochiral monomers are profoundly implausible. The presence of a natural and general Table 2: Aspects of anticipated or potential prebiotic conditions, processes, and evolutionary capacity.…”

Macrochirality of Self-Assembled and Co-assembled Supramolecular Structures of a Pair of Enantiomeric Peptides

“…Molecular chirality in amino acids, peptides, or proteins is essentially critical as they are the structural and functional basis of the organism ( Kondepudi and Nelson, 1985 ; Mason, 1986 ; Goldanskii and Kuzmin, 1988 ; Campbell, 1990 ; Bonner, 1991 ; Chelaflores, 1994 ; Friedman, 1999 ). In recent years, in addition to the chirality at the molecular level, the effects of the chirality of the supramolecular structures of proteins and peptides are attracting increasing attention due to discoveries of a series of extraordinary phenomenon ( Gutman et al, 1988 ; Surewicz and Mantsch, 1988 ; Fassihi, 1993 ; Boyd et al, 2011 ; Caglioti et al, 2011 ; Taniguchi et al, 2011 ; Gleiser and Walker, 2012 ; Ariga et al, 2020 ). For example, it has been found that the chirality of peptide nanofibers in hydrogel could affect cell adhesion and proliferation ( Das et al, 2013 ; Liu et al, 2014 ).…”

Chemical Mechanisms of Prebiotic Chirality Amplification

“…In the last decades, different hypotheses on the possible mechanisms of prebiotic, or primordial, chirality amplification were put forward and criticized from different perspectives [2,5,[16][17][18][19][20][21][22]. This contribution is aimed at considering the models relying on far-from-equilibrium chemical mechanisms of enantiomeric enrichment, essentially leaving to separate discussions crystallization-induced chirality amplifications [23], typically considered in connection with the "chance" paradigm [9].…”