Ursprung des Lebens in tiefreichenden Störungszonen: Analyse von Flüssiginklusionen und Simulationsexperimenten einer Hochdruck-Phasengleichgewichtsanlage

Bronja, Amela GND

In this thesis different analytical techniques for the verification of the theory about origin of life in deep-reaching tectonic faults were applied. Therefore, two main focusses were set. The first one was the analysis of the fluid inclusions of at least 3,2 Ga old quartz minerals from Western Australia. The second focus was the analysis of products from simulation experiments under early earth conditions in a high-pressure apparatus. In the first part of this work quartz minerals were analysed with comprehensive two-dimensional gas chromatography coupled to a quadrupole mass spectrometer (GCxGC-MS). To avoid bringing in contaminations and to release the content of the fluid inclusions, an extended sample preparation procedure was necessary. Thereby the quartz sample NJH2 shows a high amount of encapsulated organic compounds. The comparison of the analysed spots with the databases NIST and Wiley offers three substance classes. The first category consists of halogenated alcohols, alkanes and alkenes. Furthermore, non-halogenated branched alcohols were found. A homologue series of the aldehydes heptanal to hexadecanal, which were identified with standards, belong to the third substance category. The semi-quantitative analysis of these aldehydes revealed amounts of 4-32 µg/kg in the quartz sample NJH2. The reference mineral olivine, which was over a long period in direct contact to organic compounds, showed no encapsulated substances. For the liquid chromatographic analysis (LC-QTOF-MS) of the quartz sample NJH2 initially a method for data reducing and alignment was developed. With the analysed exact masses and the generated formulas, it was possible to search systematically for prebiotic molecules. The feature with m/z 163,0858 and the formula C7H9N5 stands out, because it corresponds to the purine N6, N6-Dimethyladenine. By adding ion mobility mass spectrometry (LC-IM-QTOF-MS) as third separation dimension N6, N6‑Dimethyladenine was identified. The comparison with the analytical standard shows a match of the retention time, the drift time in the drift tube and the exact mass. The substance specific CCS value, which was calculated with the drift time, was with a value of 129,3 Å2 identic. A further feature with m/z 135,0547 and formula C5H5N5 corresponds to adenine. The comparison of the exact mass and CCS value to a standard show -0,74 ppm mass difference and only 0,16 % difference to the standard CCS value of 124,3 Å2. So most probably the analysed substance is adenine. Consequently, it was shown, that the Western Australian quartzes encapsulated a variety of prebiotic compounds, which were effectively protected against degradation. In the second part of this work different simulation experiments under early earth conditions were performed. Therefore, a vesicular peptide system was generated with 12 amino acids and stearic acid/octadecylamine vesicles in the high-pressure apparatus. This system was exposed cyclic pressure variations under CO2-atmosphere for 7 days. After analysis with LC-QTOF-MS based on the exact masses, it was searched for peptide combinations, which have condensated exclusively in the presence of vesicles. The detected peptide combinations reached up to an octapeptide and had amphiphilic character. Obviously, they received a selection benefit due to integration into the vesicle membrane and the accompanying protection against hydrolysis. Whereas the vesicles experienced a stabilizing effect and their permeability increased. This means that the vesicular peptide system exhibits symbiotic properties. Another simulation experiment, in which guanine, cytosine, d-ribose and Na2HPO4 were exposed early earth conditions was performed. Again, it was searched for reaction products via LC-QTOF-MS. The condensation of guanosine and cytidine, but also of ribose phosphate was observed. Inspired by the peptide nucleic acid as precursor for the ribonucleic acid, simulation experiments with nucleic acids and amino acids were performed. Possible condensation products were also analysed with LC-QTOF-MS. The favorite condensation reaction of alanine and adenine under NH3 cleavage was noticed. Further fragmentation with direct infusion-IonTrap-MS showed, that the condensation product is indeed alanyladenine, probably N9-alanyladenine, which could be a suitable precursor for peptide nucleic acids.

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Bronja, A., 2020. Ursprung des Lebens in tiefreichenden Störungszonen: Analyse von Flüssiginklusionen und Simulationsexperimenten einer Hochdruck-Phasengleichgewichtsanlage. https://doi.org/10.17185/duepublico/73582
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