NMR evidence for Mg(II) binding to N1 of ATP

Abstract

The conformation of the complex of [ATP–Mg] 2+ is studied by 1H, 15N and 31P NMR on ATP in the absence and presence of MgCl 2 in a wide pH range from 1 to 10. 1H– 15N HMBC experiments show a large change in the 15N chemical shift of N1 up to 10 ppm around pH 3.7, suggesting that there is a strong interaction between Mg 2+ and N1 of ATP at this pH. 31P NMR indicates that at pH 3.7 the phosphate chain also binds Mg 2+. 1H diffusion measurements imply that the [ATP–Mg] 2+ complex involves only one ligand and one metal ion.