Factors influencing the stability of ATP in ternary complexes: spectroscopic investigation of the interaction of certain biomimetic copper(II) complexe with ATP and AMP

Abstract

The interaction of Cu(salgly)(H₂O) (1), Cu(sal-α -ala)(H₂O) (2), Na(salglygly)Cu(II) (3), Cu(glygly(H₂O) (4), [Cu(salen)H₂O)](ClO₄) (5), [Cu(sal-N-Meen)](ClO₄) (6), and [Cu(sal-N,N-Me₂en)(H₂O)](ClO₄) (7) with ATP and AMP has been studied using FTIR, ligand field and EPR spectroscopy, and ¹H NMR line-broadening techniques. These complexes interact equatorially with ATP through the phosphate group and with AMP through N(7), forming 1:1 species and stabilizes it from dephosphorylation. The extent of interaction of the complexes with ATP decreases in the order 1 >- 2 > 7 > 3 >- 4. EPR studies also indicate the formation of ternary species involving the γ-phosphate group of ATP and N(7) of AMP. However, the preferential broadening of H(8) resonance for all the complexes indicates the binding of ATP through N(7) of the purine base moiety and possibly through phosphate also. ATP was found to be dephosphorylated by [Cu(salen)H₂O)]⁺ and [Cu(sal-N-Meen)]⁺ complexes. Our observations indicate that the primary amino group having the potential to form hydrogen bonds with ATP coupled with the positive charge on the chelate in addition to N(7) coordination may facilitate dephosphorylation.