Abstract
The proton affinities of imidazole, oxazole, and thiazole rings, relevant to the binding of lexitropsins that contain these rings to the minor groove of DNA, are calculated using ab initio (Hartree-Fock) calculations. It is found that the proton affinities decrease in the order imidazole, oxazole, thiazole and that a methyl group substituent increases the proton affinity of imidazole, while a peptidic group decreases it.