Philippe Kopplin (Helmholtz Zentrum München)
Jeudi 9 Février - 11 h 00
Salle Manuel Forestini - IPAG
Natural organic matter (NOM) occurs in soils, freshwater and marine environments, in the atmosphere and in the form of prebiotic organic matter and represents an exceedingly complex mixture of organic compounds that collectively exhibits a nearly continuous range of properties (size-reactivity continuum). The fate NOM in the bio- and geosphere is governed according to the rather fundamental restraints of thermodynamics and kinetics. In these intricate materials, the "classical" signatures of the (geogenic or ultimately biogenic) precursor molecules, like lipids, glycans, proteins and natural products have been attenuated, often beyond recognition, during a succession of biotic and abiotic (e.g. photo- and redox chemistry) reactions. Because of this loss of biochemical signature, these materials can be designated non-repetitive complex systems. In addition, NOM is an active participant of the global carbon and other element cycles, defines the bioavailability and cycling of organic and inorganic nutrients and pollutants, making the molecular level understanding of such supermixtures a high priority topic of general interest. NOM incorporates the hugely disparate characteristics of abiotic and biotic complexity. Numerous descriptions of organic molecules present in organic chondrites 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. (ultra)High resolution analytical approaches will be presented in their application to unravel the chemical nature and organic signatures in biosystems, geosystems and selected meteorites.
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