© WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
March 08, 2012
French Research Teams Analyse Simulated Interstellar Ices
Ever since the identification of DNA by Watson and Crick as the genetic material and the elucidation of its unique information bearing structure there have been many speculations as to the evolutionary origin of this material. Now, chemical analyses of simulated interstellar ices, submitted to ultraviolet photochemistry has led to the identification of diamino acids, a new class of organic compounds. Diamino acids show a great evolutionary potential, since they were shown to form peptide nucleic acid (PNA). PNA is a potential molecular structure from which ribonucleic acid RNA and deoxyribonucleic acid DNA may have developed in distinct evolutionary processes.
The research group of Prof. Dr. Uwe Meierhenrich and Dr. Cornelia Meinert analysed simulated interstellar ices at the Chemistry Institute (CNRS UMR 7272) of the University of Nice Sophia Antipolis, France. Samples have been produced by the research group of Dr. Louis Le Sergeant d’Hendecourt and his former graduate student Pierre de Marcellus at the Institut d’Astrophysique Spatiale (CNRS UMR 8617), Paris, France. The two scientists in Nice have applied an analytical procedure developed very recently: some micrograms of simulated cometary ices in the form of organic residues were produced in Paris, by approaching interstellar conditions such as low temperature, low pressure and ultraviolet irradiation, common in interstellar space. Under ultra-clean conditions these samples were then transported to Nice, extracted and subjected to analysis by a new multidimensional GCxGC/TOF-MS instrument installed at the Institute of Chemistry ICN.
Surprisingly, the application of this technique enabled the researchers to identify 26 amino acids in the cometary ice analogue. Among them the so-called diamino acids, a special class of amino acids with an additional amino group were found. Diamino acids are thought to be of central importance in prebiotic chemical processes possibly linked to the origin of life, particularly to the origin of the genetic material. Results of molecular biological studies propose that DNA was preceded by RNA which itself was very probably preceded by peptide nucleic acids (PNA). One of the potential PNA backbones is composed of aminoethyl-glycine, a diamino acid now for the first time detected in these simulated interstellar ices. The fascinating results of this French study propose that the molecular building blocks of the potentially first genetic material may be abundant in interstellar/cometary environments. The results are published in the new interdisciplinary journal ChemPlusChem.
So far, this ″new″ and fascinating class of amino acids could hitherto not be identified in samples of simulated interstellar ices. The reason for this is probably to be found in the applied analytical procedure. Until today, for the analyses of interstellar samples and meteorites mostly classical one-dimensional gas chromatography was used. At the University of Nice Sophia Antipolis, scientists used now multidimensional gas chromatography, suitable for the separation and identification of numerous amino and diamino acids.
The detection of diamino acids in organic residues of interstellar ice analogs enables to explore new routes to interpret prebiotic chemical evolution. The results are new clues for the assumption that organic ingredients of living systems had been delivered via (micro-) meteorites and comets to the Early Earth from regions of the interstellar medium. After transport, these molecules may have participated in the initial prebiotic reactions which turned out to be of central importance for the origin of life on Earth.
The picture refers to the analysis of simulated cometary ices. New analyses were performed using a multidimensional technique–an instrument called Pegasus 4D GCxGC/TOF-MS. These analyses allowed for the identification of 26 amino acids in the simulated cometary ices. Each signal (peak) in the depicted multidimensional chromatogram below refers to a specific amino or diamino acid.
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