Thermodynamic control of asymmetric amplification in amino acid catalysis

Chemistry mirrors life Chirality, the molecular version of right- and left-handedness, has intrigued chemists ever since Pasteur found mirror-image tartaric acid crystals. The synthesis of molecules in a single chiral form is usually achieved by using a chiral entity from the outset. But in some reactions the formation of a chiral product seems to be further amplified. Most current explanations implicate autocatalysis as the source of this asymmetry. An alternative mechanism is demonstrated this week. This new approach generates a strong bias towards one chiral form from a small initial imbalance, based on the equilibrium solid–liquid phase behaviour of amino acids. As this takes place in aqueous solution, the process might explain how a prebiotic world, with left- and right-handed molecules present in equal numbers, could turn into a living world where biomolecules favour one chiral form.