A recent study reveals unexpected patterns in the rate of organic reactions when potassium (K) and sodium (Na) ions are present. Previously K+ and Na+ were thought to be ‘spectator’ ions for organic reactions, meaning they were inert and did not affect the rate at which reactions occurred. However, new research indicates that hydrolysis of glycine (G) and alanine (A) dipeptides differ in the presence of either sodium chloride (NaCl) or potassium chloride (KCl). Linear dipeptides where found to hydrolyze faster when NaCl was present, while cyclic dipeptides hydrolyzed faster with KCl. The study theorizes that a preference for K+ over Na+ inside living cells on Earth may have encouraged the formation of polypeptides.

The study, “The opposite effect of K+ and Na+ on the hydrolysis of linear and cyclic dipeptides,” was published in the journal Tetrahedron Letters. The work was performed at the NSF/NASA Center for Chemical Evolution (CCE) at the Georgia Institute of Technology in Atlanta, Georgia. The CCE is a collaborative program supported by the National Science Foundation (NSF) and the NASA Astrobiology Program.