Partial transfer of enantioselective chiralities from α-methylated amino acids, known to be of meteoritic origin, into normal amino acids

There is overwhelming evidence that meteorites bring alpha-methylated amino acids to earth with some L(S) enantiomeric excess. How does that get transferred into normal biological molecules? In this brief account, we show that an alpha-methylated amino acid, D(R)-alpha-methylvaline, can react with pyruvate and phenylpyruvate salts in dry mixtures to form alanine and phenylalanine with L enantiomeric excesses, under sensible prebiotic conditions. Thus the meteoritic L(S) excesses Of this compound would produce excess D-alanine and D-phenylalanine, which are found in some organisms. (c) 2006 Elsevier Ltd. All rights reserved.