Racemic d,l-asparagine causes enantiomeric excess of other coexisting racemic d,l-amino acids during recrystallization: a hypothesis accounting for the origin of l-amino acids in the biosphere

When recrystallizations were performed using a mixture of 12 D,L-amino acids (alanine, aspartic acid, arginine, glutamic acid, glutamine, histidine, leucine, methionine, serine, valine, phenylalanine, and tyrosine) with excess D,L-asparagine, all amino acids with the same configuration as asparagine were preferentially co-crystallized, indicating that it is the nature of a mixture of racemic amino acids to produce a spontaneous high enantiomeric excess.