The binding of metal ions to ATP: a proton and phosphorus nmr investigation of diamagnetic metal--ATP complexes.

Phosphorus and proton nmr spectra were recorded for complexes of ATp with Mg(II), Ca(II), Sr(II), Zn(II), Cd(II), Pb(II), Hg(II), Ag(I), and Tl(I) ions. Each of these ions except Hg(II) affected the 31P nmr of ATP, usually by shifting all three resonances downfield and decreasing the 31P-31P coupling constants. Pb(II) exerted the greatest shifts, while Mg(II) caused the greatest change in coupling constants. Effects on the adenine proton resonances were generally small and attributable to base stacking, but a direct metal-adenine binding is likely for Zn(II), Cd(II), and Ag(I). Effects on the ribose proton resonance were small in all of the ATP complexes, but were much larger in Zn(II)ADP and Cd(II)ADP. Formation of metal-bis(nucleotide) complexes occurred with Sn(II), Zn(II), and Cd(II).