Document Detail


On the origin of terrestrial homochirality for nucleosides and amino acids.
MedLine Citation:
PMID:  19478058     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Before life could start on earth, it was important that the amino acid building blocks be present in a predominant handedness called the L configuration and that the ribose of RNA be predominantly in the D configuration. Because ordinary chemical processes would produce them in equal L and D amounts, it has long been a puzzle how the needed selectivities could have arisen. Carbonaceous chondrites such as the Murchison meteorite, which landed in Australia in 1969, brought some unusual amino acids with a methyl group replacing their alpha hydrogen. They cannot racemize and have a small but real excess of those with the L configuration. We have shown that they can partake in a synthesis of normal L amino acids under credible prebiotic conditions. We and others showed that small preferences can be amplified into solutions with very high dominance of the L amino acids because of the higher solubility of the pure L form than of the more stable DL racemic compound crystal. Here, we show that such solubility-based amplification of small excesses of three D nucleosides, uridine, adenosine, and cytidine, can also occur to form solutions with very high D dominance under credible prebiotic conditions. Guanosine crystallizes as a conglomerate and does not amplify in this way. However, under prebiotic conditions it could have been formed from homochiral D ribose from the hydrolysis of amplified adenosine or cytidine.
Authors:
Ronald Breslow; Zhan-Ling Cheng
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.     Date:  2009-05-28
Journal Detail:
Title:  Proceedings of the National Academy of Sciences of the United States of America     Volume:  106     ISSN:  1091-6490     ISO Abbreviation:  Proc. Natl. Acad. Sci. U.S.A.     Publication Date:  2009 Jun 
Date Detail:
Created Date:  2009-06-10     Completed Date:  2009-07-06     Revised Date:  2010-09-27    
Medline Journal Info:
Nlm Unique ID:  7505876     Medline TA:  Proc Natl Acad Sci U S A     Country:  United States    
Other Details:
Languages:  eng     Pagination:  9144-6     Citation Subset:  IM    
Affiliation:
Department of Chemistry, Columbia University, New York, NY 10027, USA. rb33@columbia.edu
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MeSH Terms
Descriptor/Qualifier:
Amino Acids / chemistry*
Australia
Evolution, Chemical
Meteoroids
Nucleosides / chemistry*
Ribose / chemistry
Solubility
Stereoisomerism
Chemical
Reg. No./Substance:
0/Amino Acids; 0/Nucleosides; 50-69-1/Ribose
Comments/Corrections
Comment In:
Proc Natl Acad Sci U S A. 2009 Aug 11;106(32):E85; author reply E86   [PMID:  19666556 ]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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