Enthalpic interactions of amino acids with imidazole in aqueous solutions at 298.15 K

The enthalpies of mixing of aqueous imidazole solution and six kinds of amino acid solution (glycine, l-alanine, l-serine, l-valine, l-proline, l-threonine) have been determined at 298.15 K using a 2277 flow microcalorimetry. The results have been analyzed in terms of the McMillan–Mayer model to obtain the heterotactic enthalpic interaction coefficients. The pairwise interactions between amino acids and imidazole have been studied by a group additivity approach of savage and wood (abbreviated as SWAG). The results show that the zwitteriomic groups and different side-groups of the amino acids make their different contribution to enthalpic pair interactions.