Cyclical drying could have led to formation of earliest amino acids

Ars Technica : The process that led to the formation of the complex molecules and the development of life on Earth is still unknown. One of the big questions involves the formation of proteins, which are long chains of amino acids. Amino acids combine an acidic molecule with a nitrogen-based amine molecule . Two amino acids can bond to each other in a stable molecule, but the reaction is not energetically favorable because it produces an excess water molecule. However, increasing the concentration of amino acids in a solution increases the possibility of the reaction occurring spontaneously. A similar process happens with another molecule, lactic acid, but at a more energetically favorable rate. A new paper suggests that the drying of a solution that includes both amino acids and lactic acids could result in the two different molecules bonding together. However, over repeated cycles of drying and wetting, the amino acids replace lactic acids in the molecular chains. When the researchers tested the process, after just 20 cycles, 65% of the chains in the solution were made purely of amino acids.