FACTORS INFLUENCING THE STABILITY OF ATP IN TERNARY COMPLEXES - SPECTROSCOPIC INVESTIGATION OF THE INTERACTION OF CERTAIN BIOMIMETIC COPPER(II) COMPLEXES WITH ATP AND AMP

The interaction of Cu(salgly)(H2O) (1), Cu(sal-alpha-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-Me(2)en)(H2O)](ClO4)(7) w ith ATP and AMP has been studied using FTIR, ligand field and EPR spec troscopy, and H NMR line-broadening techniques. These complexes intera ct equatorially with ATP through the phosphate group and with AMP thro ugh 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 greater than or equal to 2 > 7 > 3 greater than or equal to 4 . EPR studies also indicate the formation of ternary species involving the gamma-phosphate group of ATP and N(7) of AMP. However, the prefer ential broadening of H(8) resonance for all the complexes indicates th e binding of ATP through N(7) of the purine base moiety and possibly t hrough phosphate also. ATP was found to be dephosphorylated by [Cu(sal en)(H2O)](+) and [Cu(sal-N-Meen)](+) complexes. Our observations indic ate that the primary amino group having the potential to form hydrogen bonds with ATP coupled with the positive charge on the chelate in add ition to N(7) coordination may facilitate dephosphorylation.