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Metabolic Pathway Confirmation and Discovery Through 13C-labeling of Proteinogenic Amino Acids
Published on: January 26, 2012
Composición isotópica de carbono de los aminoácidos individuales en el meteorito Murchison
M H Engel1, S A Macko, J A Silfer
1School of Geology and Geophysics, University of Oklahoma, Norman 73019, USA.
Nature
|November 1, 1990
Resumen
Los compuestos orgánicos de los asteroides, como el meteorito Murchison, muestran enriquecimiento de carbono-13, lo que indica orígenes extraterrestres. La alanina no racémica sugiere que las moléculas quirales prebióticas existieron en el Sistema Solar temprano antes de que surgiera la vida.
Área de la Ciencia:
- Astrobiología Astrobiología.
- La geoquímica orgánica es la geoquímica orgánica.
- Cosmoquímica es la cosmoquímica.
Sus antecedentes:
- La materia orgánica prebiótica en la Tierra temprana probablemente se originó de fuentes extraterrestres como asteroides y cometas.
- Los meteoritos carbonáceos ofrecen información sobre las vías de síntesis prebiótica y la composición orgánica de la Tierra primitiva.
- Estudios previos observaron el enriquecimiento general de 13C en aminoácidos de meteoritos, pero carecían de análisis de compuestos individuales.
Objetivo del estudio:
- Para determinar el contenido de carbono-13 (13C) de los aminoácidos individuales dentro del meteorito Murchison.
- Para investigar el origen extraterrestre y el potencial significado prebiótico de aminoácidos específicos encontrados en meteoritos.
- Para explorar la presencia de compuestos orgánicos nativos ópticamente activos en el Sistema Solar temprano.
Principales métodos:
- Análisis de aminoácidos individuales extraídos del meteorito carbónico Murchison.
- Espectrometría de masas de relación de isótopos estables para medir el contenido de 13C en aminoácidos específicos.
- Análisis quiral para evaluar la composición enantiomérica de los aminoácidos, en particular la alanina.
Principales resultados:
- Todos los aminoácidos analizados en el meteorito de Murchison exhibieron enriquecimiento en 13C, confirmando su origen extraterrestre.
- Se encontró que la alanina no era racémica, con un enriquecimiento distinto de 13C observado tanto en los enantiómeros D- como en los L-enantiómeros.
- El enriquecimiento de 13C observado en los enantiómeros de alanina sugiere una quiralidad autóctona, no una contaminación terrestre.
Conclusiones:
- Los aminoácidos de meteoritos se confirman como extraterrestres debido al enriquecimiento con 13C.
- La naturaleza no racémica de la alanina indica la presencia de materiales orgánicos ópticamente activos en el Sistema Solar temprano.
- Estos hallazgos apoyan la hipótesis de que las moléculas quirales precedieron a la vida en la Tierra y pueden haber influido en su origen.
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