Partitioning of amino acids and nucleotides between water and micellar hexadecyltrimethylammonium halides

Summary

Using quantitative gel filtration techniques partition coefficients, Kp-values, have been determined between aqueous cationic micellar hexadecyltrimethylammonium bromide, CTAB, and several biomonomer. Kp-values for 5′-adenylic acid, 5′-cytidylic acid, 5′-guanylic acid, 5′-uridylic acid and 5′-thymidylic acid are 1,400 ± 150. Nucleotides bind to CTAB micelles effectively, but nonselectively. Conversely, the binding of tRNAs to micellar CTAB is selective. Kp-values for glutamic acid II, tyrosine and phenylalanine tRNAs (in 1.0MNaCl) are 520, 3,100 and 5,600, respectively. Kp-values for the binding of alanine, arginine, aspartic acid, glutamic acid, glycine, histidine, phenylalanine, serine, threonine and tryptophan to micellar CTAB are less than 8. Conversion of unitless Kp-values for the binding of amino acids, nucleotides and nucleosides to both anionic and cationic micelles, to K (in 1/g) values allows the comparison of clays and micelles as prebiotic concentrating media. Using correlations between surface densities of the biomonomers and their binding constants, it is shown that aqueous micelles (at pH = 8) are a better concentrating media than are clays.