Understanding\nTitan’s Prebiotic Chemistry:\nSynthesizing Amino Acids Through Aminonitrile Alkaline Hydrolysis

Titan is an ocean world with a plethora of organic material\nin\nits atmosphere and on its surface, making it an intriguing location\nin the search for habitable environments beyond Earth. Settled aerosols\nwill mix with transient surface melts following cryovolcanic eruptions\nand impact events, driving hydrolysis reactions and prebiotic chemistry.\nPrevious studies have shown that the hydrolysis of laboratory-synthesized\nTitan organics leads to the production of amino acids and other prebiotic\nmolecules. The exact molecular structure of Titan aerosols remains\nunclear, yet aminonitriles have been hypothesized to be among the\norganic components. This laboratory study tested three reaction pathways\nthat could potentially lead to the formation of amino acids: aminoacetonitrile\n→ glycine, 2-aminopropanenitrile → alanine, and 4-aminobutanenitrile\n→ γ-aminobutyric acid. Liquid chromatography mass spectrometry\n(LCMS) is used to quantify the abundance of amino acids over a 6-month\nperiod. We conclude that ammonia plays a key role in the synthesis\nof amino acids from aminonitriles, while the inclusion of salts (1\nwt %) and minerals (25 mg/mL) did not have a significant effect on\namino acid formation compared to ammonia. Rate constants (<i>k</i>) for alkaline hydrolysis of the aminonitriles were calculated.\nOur results suggest that if Titan’s surface melts have a composition,\nincluding at least 5% ammonia in water, and if aminonitriles are present\nin Titan’s organic aerosols, then amino acids will likely form.\nThese results are highly relevant to the Dragonfly mission to Titan,\nwhich will sample impact melt material at Selk crater to search for\nprebiotic molecules.