ABSTRACT
The monophosphates of cytidine, uridine, and thymidine can exist as the 3' or 5' isomers. It is interesting to note that the interaction of transition metal ions with the nucleotide monophosphates takes place with N(3) ring nitrogen; the phosphate group is not involved in bonding. Interaction of metal ions with 5'-cytidine triphosphate and 5'-uridine triphosphate was studied mostly by potentiometry and 1H, 13C nuclear magnetic resonance spectroscopy.5,20 In these complexes the metal ion is usually bonded to the phosphate group with the bases free to stalk in solution. Quantitative information on the interaction of metal ions with oligo- and polynucleotides is not extensive. Proton magnetic resonance studies on the Cu(II) interaction with the polyadenine-polyuridine double helix indicate that the metal binding site is N(3) on poly U.
