ORGN 644 |
| The discovery that some meteorites contain alpha-alkyl amino acids with L enantiomeric excess (ee) up to 15% has implications for the origin of biomolecular homochirality, provided that the modest ee's of amino acids can be amplified. We herein demonstrate ee amplification of meteoritic and proteinogenic amino acids under credible prebiotic conditions. Aqueous solutions of phenylalanine with 1% ee are amplified to 90% ee by selective crystallization of the racemate. The ee of alpha-methyl valine is amplified by partially dissolving solid mixtures of alpha-methyl valine in water and separating the resulting solution via centrifugation. The maximum ee of phenylalanine attainable via crystallization is 90%, as this represents the thermodynamic equilibrium of phenylalanine crystals and the remaining phenylalanine in solution. We utilize kinetics to obtain higher ee's of phenylalanine by starting with a mixture of 80% L ee and preferentially dissolving the pure enantiomer. This process yields solutions of phenylalanine with ee's up to 95%. |
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Asymmetric Reactions, Combinatorial Chemistry, Molecular Recognition and Self-Assembly, Proteins, Peptides, Amino Acids and Enzyme Inhibitors
8:00 PM-10:00 PM, Wednesday, March 28, 2007 Hyatt Regency Chicago -- Riverside Center, Poster
Division of Organic Chemistry |