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Enantiomeric excess by magnetic circular dichroism in Archaean atmosphere

Evolution of homochirality requires an initial enantiomeric excess (EE) between right and left-handed biomolecules. We show that magnetic circular dichroism (MCD) of sun’s ultraviolet C light by oxygen in Archaean earth’s anoxic atmosphere followed by chirally selective damage of biomolecules due to...

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Autor principal: Sharma, A.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group UK 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5643348/
https://www.ncbi.nlm.nih.gov/pubmed/29038605
http://dx.doi.org/10.1038/s41598-017-13653-0
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author Sharma, A.
author_facet Sharma, A.
author_sort Sharma, A.
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description Evolution of homochirality requires an initial enantiomeric excess (EE) between right and left-handed biomolecules. We show that magnetic circular dichroism (MCD) of sun’s ultraviolet C light by oxygen in Archaean earth’s anoxic atmosphere followed by chirally selective damage of biomolecules due to circular dichroism (CD) can generate EE of correct handedness. Our calculation of EE uses published data for CD of biomolecules and accepted magnitude for Archaean earth’s magnetic field. Independent of atmospheric oxygen concentration calculated EE has the same sign for all pyrimidine nucleosides which is opposite to that for amino-acids. Purine nucleosides have smaller EE values with opposite sign to pyrimidines but are less susceptible to UV damage. Homochirality is explained by origin of prebiotic life in one hemisphere of earth and its evolution to EE ~ ± 1 before reversal of terrestrial magnetic field. Chirality of biomolecules is decided by the direction of magnetic field where prebiotic life originated on Archaean earth.
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spelling pubmed-56433482017-10-19 Enantiomeric excess by magnetic circular dichroism in Archaean atmosphere Sharma, A. Sci Rep Article Evolution of homochirality requires an initial enantiomeric excess (EE) between right and left-handed biomolecules. We show that magnetic circular dichroism (MCD) of sun’s ultraviolet C light by oxygen in Archaean earth’s anoxic atmosphere followed by chirally selective damage of biomolecules due to circular dichroism (CD) can generate EE of correct handedness. Our calculation of EE uses published data for CD of biomolecules and accepted magnitude for Archaean earth’s magnetic field. Independent of atmospheric oxygen concentration calculated EE has the same sign for all pyrimidine nucleosides which is opposite to that for amino-acids. Purine nucleosides have smaller EE values with opposite sign to pyrimidines but are less susceptible to UV damage. Homochirality is explained by origin of prebiotic life in one hemisphere of earth and its evolution to EE ~ ± 1 before reversal of terrestrial magnetic field. Chirality of biomolecules is decided by the direction of magnetic field where prebiotic life originated on Archaean earth. Nature Publishing Group UK 2017-10-16 /pmc/articles/PMC5643348/ /pubmed/29038605 http://dx.doi.org/10.1038/s41598-017-13653-0 Text en © The Author(s) 2017 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.
spellingShingle Article
Sharma, A.
Enantiomeric excess by magnetic circular dichroism in Archaean atmosphere
title Enantiomeric excess by magnetic circular dichroism in Archaean atmosphere
title_full Enantiomeric excess by magnetic circular dichroism in Archaean atmosphere
title_fullStr Enantiomeric excess by magnetic circular dichroism in Archaean atmosphere
title_full_unstemmed Enantiomeric excess by magnetic circular dichroism in Archaean atmosphere
title_short Enantiomeric excess by magnetic circular dichroism in Archaean atmosphere
title_sort enantiomeric excess by magnetic circular dichroism in archaean atmosphere
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5643348/
https://www.ncbi.nlm.nih.gov/pubmed/29038605
http://dx.doi.org/10.1038/s41598-017-13653-0
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