Amplification of Chirality through Self-Replication of Micellar Aggregates in Water

Abstract

We describe a system in which the self-replication of micellar aggregates results in a spontaneous amplification of chirality in the reaction products. In this system, amphiphiles are synthesized from two "clickable" fragments: a water-soluble "head" and a hydrophobic "tail". Under biphasic conditions, the reaction is autocatalytic, as aggregates facilitate the transfer of hydrophobic molecules to the aqueous phase. When chiral, partially enantioenriched surfactant heads are used, a strong nonlinear induction of chirality in the reaction products is observed. Preseeding the reaction mixture with an amphiphile of one chirality results in the amplification of this product and therefore information transfer between generations of self-replicating aggregates. Because our amphiphiles are capable of catalysis, information transfer, and self-assembly into bounded structures, they present a plausible model for prenucleic acid "lipid world" entities.

Protobiotic Systems Chemistry Analyzed by Molecular Dynamics

“…These experiments would require complex setups and accurate compositional monitoring of individual microscopic amphiphile assemblies, currently mostly outside the realm of experimental scrutiny. Some promising leads do however exist in the recent experimental exploration of multi-component lipid vesicles [42,43,44,45]. Another critique of GARD asserts that it simulates abstract molecules without specified chemical properties.…”

Twenty Years of “Lipid World”: A Fertile Partnership with David Deamer

“…A specific embodiment of such simulations could test the feasibility of homeostatic growth and reproduction of vesicles with novel lipids generated by lipozyme catalysis, as well as reproduction of the lumenal content [36]. These simulations should be accompanied by parallel laboratory evidence of individual processes relevant for such behavior, including recent evidence of mutually catalytic lipid networks [69][70][71], and amplification of chirality through self-replication of micellar amphiphile assemblies [72]. Future expansion of such evidence will help unfold the complexification of the Lipid World.…”

Enceladus: First Observed Primordial Soup Could Arbitrate Origin-of-Life Debate

“…In LF, compositional information, although less efficient, is still stored and transmitted upon assembly growth-fission cycles. While there is an admitted paucity of experimental data to directly back such a scenario, supporting data are beginning to accumulate (Bukhryakov et al, 2015), and it is hard to miss the analogy of compositional reproduction to epigenetic inheritance (Pulselli et al, 2009), a cornerstone of information transfer in nowadays living cells (Dupont et al, 2009). Catalysis: In parallel to free energy source, this is a fundamental requirement for a lifelike entity to sustain itself away from equilibrium.…”

“…Catalysis is facilitated by restriction to 2-D diffusion (reduced dimensionality [McCloskey and Poo, 1986]) and by curvature-induced free energy gradients (Seifert, 1993). Lipid assemblies have also been experimentally shown to harbor rudimentary mutually catalytic networks, with a capacity for replication-like behavior (Bukhryakov et al, 2015; Hardy et al, 2015).…”

“…The advantage of Lipid First assemblies is that being capable of systems reproduction, selection, and evolution (Markovitch and Lancet, 2014), they can complexify by evolutionary paths simulatable by molecular dynamics (Lancet et al, 2018). Since lipids with peptide and oligonucleotide headgroups do exist (Bukhryakov et al, 2015; Hardy et al, 2015), new chemistries can emerge, based on heterotrophic availability or endogenous evolution-driven synthesis. Notably, since lipids in present-day life obey specific structural and functional constraints (Georgiou and Deamer, 2014), lipid structure evolution is also expected to occur en route to more elaborate life-forms.…”