Abstract
Amino acids and polycyclic aromatic hydrocarbons (PAHs) belong to the range of organic compounds detected in meteorites. In this study, we tested empirically and theoretically if PAHs are precursors for amino acids in carbonaceous chondrites, as previously suggested. We conducted experiments to synthesize amino acids from fluoranthene (PAH), with ammonium bicarbonate as a source for ammonia and carbon dioxide under mimicked asteroidal conditions. In our thermodynamic calculations, we extended our analysis to additional PAH–amino acid combinations. We explored 36 reactions involving the PAHs naphthalene, anthracene, fluoranthene, pyrene, triphenylene, and coronene and the amino acids glycine, alanine, valine, leucine, phenylalanine, and tyrosine. Our experiments do not show the formation of amino acids, whereas our theoretical results hint that PAHs could be precursors of amino acids in carbonaceous chondrites at low temperatures.
Highlights
Carbonaceous chondrites that are found on Earth contain a multitude of organic compounds.[1−4] Amino acids, the monomers of proteins, are well-known examples of organic molecules occurring both in terrestrial life forms and in meteorites.[5−9] Over the years, different amino acid-forming processes in carbonaceous chondrites have been proposed and experimentally tested.[4,10−13] The best-known reaction is the Strecker synthesis
Amino acids are formed through a nucleophilic addition of an aldehyde, such as formaldehyde (CH2O), with ammoniausinsoltuhteiopnr.1e4s−e1n6ceAnofalhteyrdnraotgiveenyecyt alnesidseer-(stHudCiNed) in an theory developed by Shock and Schulte (1990)[10] suggests that polycyclic aromatic hydrocarbons (PAHs) serve as a precursor for amino acids during hydrothermal alteration in meteorite parent bodies
To examine the feasibility of amino acid formation by PAHs and the potential catalytic role of olivine, we investigated the link between PAHs and the formation of amino acids in carbonaceous chondrites using two approaches
Summary
Carbonaceous chondrites that are found on Earth contain a multitude of organic compounds.[1−4] Amino acids, the monomers of proteins, are well-known examples of organic molecules occurring both in terrestrial life forms and in meteorites.[5−9] Over the years, different amino acid-forming processes in carbonaceous chondrites have been proposed and experimentally tested.[4,10−13] The best-known reaction is the Strecker synthesis In this synthesis, amino acids are formed through a nucleophilic addition (multistep reaction) of an aldehyde, such as formaldehyde (CH2O), with ammonia (aNquHeo3)usinsoltuhteiopnr.1e4s−e1n6ceAnofalhteyrdnraotgiveenyecyt alnesidseer-(stHudCiNed) in an theory developed by Shock and Schulte (1990)[10] suggests that polycyclic aromatic hydrocarbons (PAHs) serve as a precursor for amino acids during hydrothermal alteration in meteorite parent bodies. A direct link between the alteration of olivine and alteration as well as reactivity of PAHs in such experiments has not been established
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