Formation of nucleobases in a Miller–Urey reducing atmosphere
Martin Ferusa, Fabio Pietruccib, Antonino Marco Saittab, Antonín Knížeka,c, Petr Kubelíka, Ondřej Ivaneka, Violetta Shestivskaa, and Svatopluk Civiša,1
Author Affiliations
a J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, CZ18223 Prague 8, Czech Republic;
b Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, Université Pierre et Marie Curie, Sorbonne Universités, CNRS, Muséum National d’Histoire Naturelle, Institut de Recherche pour le Développement, UMR 7590, F-75005 Paris, France;
c Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University in Prague, CZ12840 Prague 2, Czech Republic
Edited by Jerrold Meinwald, Cornell University, Ithaca, NY, and approved March 13, 2017 (received for review January 6, 2017)
Source/Fonte: https://media.giphy.com/media/APKV6mdZxThIs/giphy.gif
Abstract
Significance
The study shows that Miller–Urey experiments produce RNA nucleobases in discharges and laser-driven plasma impact simulations carried out in a simple prototype of reducing atmosphere containing ammonia and carbon monoxide. We carried out a self-standing description of chemistry relevant to hypothesis of abiotic synthesis of RNA nucleobases related to early-Earth chemical evolution under reducing conditions. The research addresses the chemistry of simple-model reducing atmosphere (NH3 + CO + H2O) and the role of formamide as an intermediate of nucleobase formation in Miller–Urey experiment. The explorations combine experiments performed using modern techniques of large, high-power shock wave plasma generation by hall terawatt lasers, electric discharges, and state-of-the-art ab initio free-energy calculations.
Abstract
The Miller–Urey experiments pioneered modern research on the molecular origins of life, but their actual relevance in this field was later questioned because the gas mixture used in their research is considered too reducing with respect to the most accepted hypotheses for the conditions on primordial Earth. In particular, the production of only amino acids has been taken as evidence of the limited relevance of the results. Here, we report an experimental work, combined with state-of-the-art computational methods, in which both electric discharge and laser-driven plasma impact simulations were carried out in a reducing atmosphere containing NH3 + CO. We show that RNA nucleobases are synthesized in these experiments, strongly supporting the possibility of the emergence of biologically relevant molecules in a reducing atmosphere. The reconstructed synthetic pathways indicate that small radicals and formamide play a crucial role, in agreement with a number of recent experimental and theoretical results.
life origins asteroid impact reducing atmosphere
Footnotes
1To whom correspondence should be addressed. Email: svatopluk.civis@jh-inst.cas.cz.
Author contributions: M.F., F.P., A.M.S., and S.C. designed research; M.F., A.K., O.I., and S.C. performed experimental research; F.P. and A.M.S. performed computer simulations; M.F., F.P., A.M.S., P.K., O.I., V.S., and S.C. analyzed data; and M.F., F.P., A.M.S., and S.C. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1700010114/-/DCSupplemental.
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NOTA DESTE BLOGGER:
Repare que eles transformaram a frase "laser-driven plasma impact simulations" em "we show that RNA nucleobases are synthesized in these experiments..." Uau! Simulações virtuais!
Será? Onde? Dentro do computador? Ou dentro do programa? Ou simplesmente dentro das bases de dados? As perguntas que devem ser feitas: Vocês podem nos dizer o estado racêmico dessas nucleobases simuladas? E quantos isômeros inativos se formaram comparados com as versões dos isômeros biologicamente ativos? Dá para ficar rico vendendo esse material para outros químicos?
Se um computador esteve envolvido, então tudo é VIRTUAL. Pelas barbas de Darwin, não poluam a literatura científica com dados vituais.
