Sprecher
Beschreibung
The complexity of solution compositions in natural OOL scenarios is in stark contrast to the often specifc initial requirements of reactions in prebiotic chemistry or molecular evolution. Failure to meet these conditions, as is often the case in natural environments, leads quite often to a multitude of undesired side products with low or vanishing yields of the target products. Heat fluxes through water-filled thin cracks in geomaterials offer an interesting approach to this problem for nature: the ubiquitous heat fluxes lead to a strong concentration of prebiotically relevant substances in the thin fluid layers. We show experimentally that the strength of this effect differs significantly even for extremely similar chemicals such as linear or cyclic phosphorylated nucleotides or the canonical bases, but also for most canonical amino acids. If the said rock cracks form a interconnected system, the selective effect is enhanced even at small temperature differences leading to relative concentration differences of several orders of magnitude between different chemicals such as 2-aminooxazoles versus 2-aminoimidazoles. Locally, a variety of solution compositions can thus be implemented and a wide range of reaction conditions can be provided. We demonstrate this using the example of the enrichment of magnesium over sodium ions from basalt leachates, in which the high sodium concentrations actually inhibit the function of ligase ribozymes. Only heat flux-driven selective enrichment of magnesium ions establishes the necessary reaction conditions and enables ligation. Selective concentration also leads to the separation of calcium from phosphate, providing a pathway for the release of phosphate from otherwise difficult-to-access apatite mineral. Even in simple salt solutions without further buffering, separation of ion pairs can produce pH differences of up to 4 units within a few centimeters. Heat fluxes through such plausible geomicrofluidics thus couple to a variety of chemically relevant gradients, and their wide availability provides ideal conditions for enabling prebiotically relevant reactions.
References:
T. Matreux, K. Le Vay, A. Schmid, P. Aikkila, L. Belohlavek, A. Z. Çalışkanoğlu, E. Salibi, A. Kühnlein, C. Springsklee, B. Scheu, D. B. Dingwell, D. Braun, H. Mutschler, C. B. Mast, Nature Chemistry doi.org/10.1038/s41557-021-00772-5 (2021)
