Reactions On Copper Surfaces Could Provide New Insight Into Origin Of Life Questions

Amino acids, sugars, and other earthly biomolecules have a predominant handedness, and one of the enduring questions about life’s origins is how that chiral bias originated. New work with chiral metal surfaces may provide further insight into one theory: Chiral mineral surfaces on early Earth acted as catalysts that favored certain enantiomers. Andrew J. Gellman of Carnegie Mellon University, a pioneer in producing chiral metal surfaces, led the study. His team adsorbed enantiomers of tartaric acid on naturally chiral, single-crystal copper surfaces (models shown) in a vacuum and followed their decomposition to carbon dioxide, hydrogen, water, and hydrocarbons. Sure enough, the two enantiomers’ decomposition rates differed by up to a factor of 50 (J. Am. Chem. Soc. 2013, DOI: 10.1021/ja408659v). Gellman attributes this observation to highly nonlinear kinetics: Each time a tartaric acid molecule decomposes, it exposes two chiral copper surface sites, which then catalyze two more decompositions, and so on. This phenomenon might also apply to enantioselective catalysis on be applicable, Gellman adds.