Spectroscopic Properties of Metal-Nucleotide and Metal-Nucleic Acid Interactions

Abstract

The Fourier Transform Infrared Spectra of a series of mononucleotides and their transition and non-transition metal complexes are studied and discussed. The potential coordination sites of the mononucleotides are analysed with respect to the various metals employed. Several complexes which were structurally known have been investigated in order to relate their crystal structures to the infrared spectra and vice versa. The binding sites of the bases and phosphate when coordinated to the metals produce modification in the infrared spectra of the mononucleotides which often can be diagnostic of the binding sites involved in coordination. It has been found that the purine base is coordinated to the metals through the N7 atom of guanine. In addition the phosphate group is also bound to the metal either directly or indirectly through a coordinated water molecule forming hydrogen bonding with the negative oxygen atoms of the phosphate group. The N7 binding produces considerable changes in the skeletal vibrations of the imidazole ring, while the direct phosphate binding produces changes in the phosphate vibrations of the PO₃ ²⁺ group, which are diagnostic of direct or indirect metal coordination.