Differential adsorption of nucleic acid bases: Relevance to the origin of life

The adsorption of organic molecules onto the surfaces of inorganic solids h as long been considered a process relevant to the origin of life. We have d etermined the equilibrium adsorption isotherms for the nucleic acid purine and pyrimidine bases dissolved in water on the surface of crystalline graph ite. The markedly different adsorption behavior of the bases describes an e lutropic series: guanine > adenine > hypoxanthine > thymine > cytosine > ur acil. We propose that such differential properties were relevant to the pre biotic chemistry of the bases and may have influenced the composition of th e primordial genetic architecture.