Em entrevista concedida ao Science Daily, o Dr. Daniel Glavin, do Centro de Voo Espacial Goddard da NASA, em Greenbelt, Maryland, disse:
“Nós descobrimos mais apoio para a ideia de que as moléculas biológicas, como os aminoácidos, criadas no espaço e trazidas para a Terra por impactos de meteoritos ajudam a explicar por que a vida tem preferência para o lado esquerdo. Com isso eu quero dizer por que toda a vida conhecida usa somente as versões levógiras (lado esquerdo) de aminoácidos para construir proteínas.”
Glavin é o principal autor do artigo desta pesquisa que foi publicada no PNAS -Proceedings of the National Academy of Sciences, de 16 de março de 2009.
Leia o artigo Clues To A Secret Of Life Found In Meteorite Dust do ScienceDaily aqui.
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Artigo do PNAS
Enrichment of the amino acid l-isovaline by aqueous alteration on CI and CM meteorite parent bodies
1. Daniel P. Glavin,1 and
2. Jason P. Dworkin
Edited by Jack W. Szostak, Massachusetts General Hospital, Boston, MA, and approved January 23, 2009 (received for review November 15, 2008)
Abstract
The distribution and enantiomeric composition of the 5-carbon (C5) amino acids found in CI-, CM-, and CR-type carbonaceous meteorites were investigated by using liquid chromatography fluorescence detection/TOF-MS coupled with o-phthaldialdehyde/N-acetyl-l-cysteine derivatization. A large l-enantiomeric excess (ee) of the α-methyl amino acid isovaline was found in the CM meteorite Murchison (lee = 18.5 ± 2.6%) and the CI meteorite Orgueil (lee = 15.2 ± 4.0%). The measured value for Murchison is the largest enantiomeric excess in any meteorite reported to date, and the Orgueil measurement of an isovaline excess has not been reported previously for this or any CI meteorite. The l-isovaline enrichments in these two carbonaceous meteorites cannot be the result of interference from other C5 amino acid isomers present in the samples, analytical biases, or terrestrial amino acid contamination. We observed no l-isovaline enrichment for the most primitive unaltered Antarctic CR meteorites EET 92042 and QUE 99177. These results are inconsistent with UV circularly polarized light as the primary mechanism for l-isovaline enrichment and indicate that amplification of a small initial isovaline asymmetry in Murchison and Orgueil occurred during an extended aqueous alteration phase on the meteorite parent bodies. The large asymmetry in isovaline and other α-dialkyl amino acids found in altered CI and CM meteorites suggests that amino acids delivered by asteroids, comets, and their fragments would have biased the Earth's prebiotic organic inventory with left-handed molecules before the origin of life.
Keywords:
enantiomeric excess homochirality origin of life carbonaceous chondrite
1To whom correspondence should be addressed. E-mail:daniel.p.glavin@nasa.gov
Author contributions: D.P.G. and J.P.D. designed research, performed research, contributed new reagents/analytic tools, analyzed data, and wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
PDF do artigo gratuito aqui.
