Abstract
Many approaches to the origin of life focus on how the molecules found in biology might be made in the absence of biological processes, from the simplest plausible starting materials. Another approach could be to view the emergence of the chemistry of biology as process whereby the environment effectively directs "primordial soups" toward structure, function, and genetic systems over time. This does not require the molecules found in biology today to be made initially, and leads to the hypothesis that environment can direct chemical soups toward order, and eventually living systems. Herein, we show how unconstrained condensation reactions can be steered by changes in the reaction environment, such as order of reactant addition, and addition of salts or minerals. Using omics techniques to survey the resulting chemical ensembles we demonstrate there are distinct, significant, and reproducible differences between the product mixtures. Furthermore, we observe that these differences in composition have consequences, manifested in clearly different structural and functional properties. We demonstrate that simple variations in environmental parameters lead to differentiation of distinct chemical ensembles from both amino acid mixtures and a primordial soup model. We show that the synthetic complexity emerging from such unconstrained reactions is not as intractable as often suggested, when viewed through a chemically agnostic lens. An open approach to complexity can generate compositional, structural, and functional diversity from fixed sets of simple starting materials, suggesting that differentiation of chemical ensembles can occur in the wider environment without the need for biological machinery.
Highlights
Modern synthetic chemistry takes a closed approach to complexity, with a focus on making single molecular targets in high yield, purity, and selectivity
We show that performing a reaction of the same starting materials but under different environmental conditions will consistently yield different chemical ensembles (Fig. 1)
Addition of salts and minerals are both known to interact with amino acid (AA) in a variety of ways, causing either catalysis, complexation, sequestration, degradation, and/or templating [30,31,32,33,34]
Summary
Modern synthetic chemistry takes a closed approach to complexity, with a focus on making single molecular targets in high yield, purity, and selectivity. Most chemists researching life-like systems [10] have moved from exploring high-energy unconstrained primordial soup reactions [11, 12], to examining the intricate mechanisms required for abiotic synthesis of nucleotides [13], polynucleotides [14,15,16], and peptides [17,18,19,20], and on toward the assembly of protocells [12,13,14,15,16,17,18,19,20,21,22,23], enzyme-mediated systems [24], and exploration of autocatalysis [25, 26]. We show that performing a reaction of the same starting materials but under different environmental conditions will consistently yield different chemical ensembles (Fig. 1) These can lead to the emergence of distinct order, structure, and function, “programmed” by the environment, and challenge the view that a complexity-first approach, instead of targeting specific product molecules, will only yield intractable tar [7]. R.E.P. is a guest editor invited by the Editorial Board
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