| Abstrakt: |
Geological conditions play a significant role in prebiotic/abiotic organic chemistry, especially when reactive minerals are present. Previous studies of the prebiotic synthesis of amino acids and other products in mineral‐containing systems have shown that a diverse array of compounds can be produced, depending on the experimental conditions. However, these previous experiments have not simulated the effects of varying geochemical conditions, in which factors such as pH, iron redox state, or chemical concentrations may vary over time and space in a natural environment. In geochemical systems that contain overlapping gradients, many permutations of individual conditions could exist and affect the outcome of an organic reaction network. We investigated reactions of pyruvate and glyoxylate, two compounds that are central to the emergence of metabolism, in simulated geological gradients of redox, pH, and ammonia concentration. Our results show that the positioning of pyruvate/glyoxylate reactions in this environmental parameter space determines the organic product distribution that results. Therefore, the distribution pattern of amino acids and alpha‐hydroxy acids produced prebiotically in a system reflects the specific reaction conditions, and would be distinct at various locations in an environment depending on local geochemistry. This is significant for origin of life chemistry in which the composition and function of oligomers could be affected by the environmentally driven distribution of monomers available. Also, for astrobiology and planetary science where organic distribution patterns are sometimes considered as a possible biosignature, it is important to consider environmentally driven abiotic organic reactions that might produce similar effects. Plain Language Summary: To understand the potential for life elsewhere, it is important to try to find organic molecules on other planets, but also to understand the "pattern distributions" of organics–that is, the relative amounts of different organic molecules in a system. It is possible that organic distribution patterns could be a biosignature, but only if they can be deconvoluted from nonbiological organic chemistry. We conducted lab simulations of abiotic organic reactions (of important prebiotic molecules) in systems containing reactive iron minerals, similar to conditions that might exist in a variety of planetary environments as well as the early Earth when life emerged. We studied the distributions of products that are formed in this reaction as a function of conditions that would exist in geological environments, and found that different amounts of specific organic products were formed depending on the starting conditions. Our findings illustrate how, even in nonbiological systems, there is a lot of variety in the outcomes of organic chemical reactions and it is important to fully characterize abiotic systems to be able to identify systems that might contain life. Key Points: Varying geochemical parameters of iron redox state, pH, and ammonia concentration affect the outcome of an organic reaction networkOrganic pattern distributions produced abiotically in geological systems are not random and vary depending on the geochemical conditionsEnvironmental conditions affect the relative amounts of organics formed in this mineral system, which has implications for biosignature detection and prebiotic chemistry [ABSTRACT FROM AUTHOR] |
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