Abstract EANA2024-9

Many studies have been performed to investigate minerals as catalysts for prebiotic peptide formation. However, most adsorb molecules via multiple points of attachment, making the polymer inherently hard to remove, and so the question becomes “how did life escape mineral surfaces?”.[1] In contrast, layered double hydroxides (LDHs), a rarely studied group of minerals, have been shown to allow mobility in adsorbed molecules as only the negative C-terminus adsorbs.[2] It has been proposed that these minerals could be the origin of prebiotic peptides, through concentrating amino acids and promoting peptide bond formation. However, this has only been shown computationally,[2] with experimental evidence only available for the formation of dipeptides.[3]

Shallow-sea alkaline hydrothermal vents are an often overlooked prebiotically-relevant environment, providing hybrid conditions between deep-sea vents and terrestrial springs. Due to tides, these vents are often alternatingly submerged (in freshwater or seawater) and exposed to the atmosphere, providing continuous wetting-drying cycles.[4] Layered double hydroxides are thought to have been widely distributed at these vents on the early Earth, formed through serpentinization reactions or from brucite (Mg(OH)2).[5] Therefore, LDHs at these shallow-sea vents are excellent candidates for the origin of prebiotic peptides, as dehydration of the mineral drives the polymerisation reaction entropically, while rehydration allows for the removal of the formed peptide and repopulation of the amino acids.

We carried out experiments to polymerise glycine using Mg2Al-LDH. However, unlike previous experiments, we repopulated the amino acids during each rewetting step, which we suspect was the limiting factor in these tests. We believe this is more accurate for origin of life scenarios, as amino acids are thought to have been widely available on the early Earth, through extraterrestrial delivery or endogenic synthesis. Therefore, more amino acids would have become adsorbed onto the mineral surface. While the origins of life have geological timescales at their disposal, neither our lifetime nor laboratory constraints permit us to attempt such slow experiments. Therefore, we also adapted the previous experiments by using a nitrogen atmosphere and a nitrate-intercalated LDH, to ensure maximum adsorption of the amino acid to the mineral surface, so as to increase the possibility for peptide bond formation. We will present the first results of these experiments.

(1)          Lambert, J. F. Adsorption and Polymerization of Amino Acids on Mineral Surfaces: A Review. Origins of Life and Evolution of Biospheres 2008, 38 (3), 211–242. https://doi.org/10.1007/S11084-008-9128-3.

(2)          Erastova, V.; Degiacomi, M. T.; Fraser, D. G.; Greenwell, H. C. Mineral Surface Chemistry Control for Origin of Prebiotic Peptides. Nat Commun 2017, 8 (1), 1–9. https://doi.org/10.1038/s41467-017-02248-y.

(3)          Grégoire, B.; Greenwell, H. C.; Fraser, D. G. Peptide Formation on Layered Mineral Surfaces: The Key Role of Brucite-like Minerals on the Enhanced Formation of Alanine Dipeptides. ACS Earth Space Chem2018, 2 (8), 852–862. https://doi.org/10.1021/ACSEARTHSPACECHEM.8B00052.

(4)          Barge, L. M.; Price, R. E. Diverse Geochemical Conditions for Prebiotic Chemistry in Shallow-Sea Alkaline Hydrothermal Vents. Nat Geosci 2022, 15 (12), 976–981. https://doi.org/10.1038/s41561-022-01067-1.

(5)          Arrhenius, G. O. Crystals and Life. Helv Chim Acta 2003, 86 (5), 1569–1586. https://doi.org/10.1002/HLCA.200390135.