QUANTITATIVE INVESTIGATION OF THE INTERACTION OF COPPER(II) AND MANGANESE(II) WITH SOME PURINE-BASES, NUCLEOSIDES AND NUCLEOTIDES BY NUCLEAR MAGNETIC-RESONANCE

The aqueous solution interaction between Cu(II) or Mn(II) and base coordination sites on some purine bases is examined quantitatively. For Cu(II) it was found that a relatively strong chelate is formed with adenines through coordination at N-7 and the amino group ( or imine group). When the C-6 substituent is an oxygen donor a chelate structure is not found and monodentate coordination at N-7 predominates. Mn(II) interacts with hypoxanthines and inosines only through formation of a chelate at N-7 and the C-6 substituent. The competition between base and phosphate for these metal ions is examined by studying the 3′: 5′ nucleotides. Cu(II) interacts only with the base of cyclic AMP but ca. 50% of the Cu(II) is phosphate bound with cyclic IMP and 6-chloropurine-riboside 3′: 5′ phosphate. Mn(II) is predominantly phosphate bound with cyclic IMP and almost wholly so with the others. © 1979.