Interaction of metal ions with 5'-guanosine monophosphate-Evidence for binding through N(1) in solution

Abstract

The stability constants of Cu(II), Ni(II), Zn(II) and Co(II) binary complexes (1:1) with 5-guanosine monophosphate (5-GMP) as the primary ligand and of the corresponding ternary complexes (1:1:1) with glycine, histidine and histamine as the secondary ligands have been determined potentiometrially at 35°C and 0.10 <em>M </em>(KNO₃) ionic strength. In the acidic medium, N (7) and phosphate oxygen of 5'- GMP are found to be more favoured coordination sites; the preference for N(1) increases with increase in <em>p</em>H<em>. </em>This multi-site bonding behaviour of 5'-GMP towards cations in solution has been investigated and the influence of <em>p</em>H on the coordinating abilities of 5'-GMP assessed. The influence of secondary ligands on the stabilities of M(II)-5'-GMP sysems is also discussed. Species distribution curves have been obtained using the computer programme BEST.