Thermodynamics and the mechanism of interactiton of adenine with amino acids in water

Two groups of amino acids, which react differently with adenine, are distin guished. In the case of nonpolar and aliphatic amino acids, the endothermic effect of dehydration plays a decisive role, while in the case of aromatic , polar, and charged amino acids the exothermic effect of interaction with adenine is dominant. Associates of Ade with Lys HCl, His, Trp, Asp, and Glu were found. It was demonstrated that the complex-forming ability of purine s (Ade and Caf) is higher than that of pyrimidines. Based on the linear ent halpy-entropy compensation effect for complexes of amino acids with adenine , it was suggested that the hydration state of interacting molecules contri butes significantly to interactions of Ade with amino acids.