Does Crystallization Lead to Homochirality?
A research team from Columbia University, headed up by Ronald Breslow, believes it can explain how homochirality emerged. These investigators have previously demonstrated that when amino acids crystallize out of solution in which there is a slight excess of one enantiomer, the ensuing crystal possesses a 50:50 mixture of the two enantiomers. On the other hand, the liquid phase becomes enriched with the enantiomer that initially was in slight excess. They have shown that a slight chiral excess of about 1% can quickly become amplified to about 90% after two rounds of crystallization. The reason for this enrichment stems from the reduced solubility of amino acid complexes formed when left-handed and right-handed versions combine compared to complexes formed from left-handed and left-handed forms (or right-handed and right-handed forms). The difference in solubility will cause the crystal to exclude the enantiomer that is initially in excess. Based on this behavior, the Columbia team propo
