High molecular diversity of extraterrestrial organic matter in Murchison meteorite revealed 40 years after its fall

Abstract

Numerous descriptions of organic molecules present in the Murchison meteorite have improved our understanding of the early interstellar chemistry that operated at or just before the birth of our solar system. However, all molecular analyses were so far targeted toward selected classes of compounds with a particular emphasis on biologically active components in the context of prebiotic chemistry. Here we demonstrate that a nontargeted ultrahigh-resolution molecular analysis of the solvent-accessible organic fraction of Murchison extracted under mild conditions allows one to extend its indigenous chemical diversity to tens of thousands of different molecular compositions and likely millions of diverse structures. This molecular complexity, which provides hints on heteroatoms chronological assembly, suggests that the extraterrestrial chemodiversity is high compared to terrestrial relevant biologicaland biogeochemical-driven chemical space.Fourier transform ion cyclotron resonance mass spectrometry | interstellar chemistry | nuclear magnetic resonance spectroscopy | organic chondrite | soluble organic matter M urchison chondrite is one of the most studied meteorites and became a reference for extraterrestrial organic chemistry (1). The diversity of organic compounds recorded in Murchison and in other carbon-rich carbonaceous chondrites (1-5) has clearly improved our understanding of the early interstellar chemistry that operated at or just before the birth of our solar system. More than 70% of the Murchison carbon content has been classified as (macromolecular) insoluble organic matter (IOM) of high aromaticity, whereas the soluble fraction contains extensive suites of organic molecules with more than 500 structures identified so far (6). These structures basically resemble known biomolecules, but are considered to result from abiotic synthesis because of peculiar occurrence patterns, racemic mixtures, and stable isotope contents and distributions. Most of the 100+ kg fragments of Murchison were collected shortly after it fell in Australia on September 28, 1969, so that neither of these fresh samples suffered from intensive terrestrial weathering (7).As a whole, Murchison is one of the least-altered chondrites (8), recently reclassified by Rubin et al. (9) as CM2.5, where the aqueous alteration index (2.5 petrologic subtype), based on petrographic and mineralogical properties of the meteorite, indicates that the primary lithology of Murchison had experienced a relatively low and uniform degree of aqueous alteration.Nevertheless, all previous molecular analyses were targeted toward selected classes of compounds with a particular emphasis on amino acids in the context of prebiotic chemistry as potential source of life on earth (10), or on compounds obtained in chemical degradation studies (11) releasing both genuine extractable molecules and reaction products (11-15) often difficult to discern unambiguously.Alternative nontargeted investigations of complex organic systems are now feasible using advanced analytical met...

Meteorite-catalyzed syntheses of nucleosides and of other prebiotic compounds from formamide under proton irradiation

“…The analysis of amino acids was limited to a selected panel of meteorites. We observed, as abundant products, glycine (51), N-formylglycine (52), alanine (53), N-formylalanine (54), 2-methylalanine (55), proline (56), pyroglutamic acid (57), β-amino isobutyric acid (AIBA) (58), and 2-pyrrolidone (59) (Fig. 2 and Table 5).…”

“…Meteorites might have played a major role in the chemical inventory of the early solar system for origin-of-life processes, behaving (52,53) as carriers of organic molecules in connection with the Earth heavy-bombardment period (54,55) and preceding the supposed earliest existence of living organisms (56). Evidence of the catalytic properties of meteorites in prebiotic chemistry was recently provided by thermal processes of condensed-phase FA at relatively high temperatures (333 and 413 K) (57,58) or at the most extreme temperature conditions modeling impact events in Earth's atmosphere or surface (3,59).…”

Astrobiology and the Possibility of Life on Earth and Elsewhere…

“…Moreover, in addition to highly scrutinized compounds such as amino acids, nucleobases and sugars, bulk analysis using high resolution mass spectrometry of the soluble fraction of the Murchison meteorite has revealed tens of thousands of different molecular formulae, likely representing millions of organic structures (Schmitt-Kopplin et al 2010). Therefore comets, MMs, IDPs and meteorites may have provided a wealth of building blocks for life just before the first living organism appeared on our planet.…”

Catalysis in the Primordial World

“…BSA -bovine serum albumin -albumin goveđeg seruma DKP -diketopyranozide (cyclic dimer of amino acids) -diketopiranozid (ciklički dimer aminokiselina) EDAC -1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (condensing agent) -1-etil-3-(3-dimetilaminopropil)karbodiimid (agens za kondenzaciju) Ga -gigaannum, 10 9 years -gigagodina, 10 9 godina IDP -interplanetary dust particle -međuplanetarna čestica prašine Imp -imidazole-5'-phosphate -imidazol-5'-fosfat IOM -insoluble organic matter -netopljiva organska tvar Meadp -1-methyladenine-5'-phosphate -1-metiladenin-5'-fosfat PNA -peptide nucleic acid -peptidna nukleinska kiselina…”

“…There are literally millions of different organic compounds in the Murchison meteorite alone, of which 683 were positively identified. 10 Chyba and Sagan estimated an input 10 7 -10 9 kg yr −1 of organic material from cometary and asteroidal interplanetary dust particles (IDPs) on early Earth. 11 The next problem with the Urey-Miller experiment is that primordial Earth's atmosphere was not Jupiter-like, composed of hydrogen, methane, ammonia and water vapour, as Urey proposed.…”