[Enthalpy of interaction of amino acids and peptides with 6-azauracil in water]

We have determined the enthalpies of dissolution of 6-azauracil in aqueous solutions of amino acids and peptides at the 25 degrees C, and the enthalpic coefficients of their pair interactions in water have been calculated on the basis of McMillan-Mayer formalism. The analysis of hydration of zwitterion and side chain of amino acids and peptides on an interaction character has been done. The comparison of the interaction coefficients of 6-azauracil with amino acids and the linear peptides shows that this interaction is localized near the one of zwitterion charged groups.