Interaction of metal ions with uridine 5' -monophosphate: Existence of possible intramolecular interactions

Abstract

Interaction of Cu²⁺, NF⁺, Zn²⁺, Co²⁺, Mg²⁺, Ca²⁺, La³⁺, Pr³⁺, Nd³⁺, Gd³⁺ monophosphate (5'-UMP) as the primary ligand and glycine (gly), histidine (histi) and histamine (hista) as secondary ligands in 1: 1 and 1:1:1 ratio has been investigated potentiometrically at 35°C and 0.10 <em>M</em> (KNO₃) ionic strength. The stability constants of binary (1:1) and ternary (1:1:1) systems are compared to assess the influence of charge of the metal ions and the nature of secondary ligands on the structure and stabilities of these complexes. The stabilisation of the ternary complexes is measured in terms of <img src='http://www.niscair.res.in/jinfo/delta.gif' border=0> log <em>K </em>which is the difference between the stabilities of binary and ternary complexes in solution. Based on geometry of metal-5'-UMP complexes, coordination number of the metal ions concerned and the sterle factors, it has been concluded that O(4) is also involved in coordination in addition to the known phosphate binding in binary complexes. However, in ternary systems only phosphate is involved in metal coordination.