REACTIVITIES AND SITE-SELECTIVITIES OF HYDROLYZES OF ATP AND UTP PROMOTED BY METAL-COMPLEXES OF ADENINE-LINKED DI-2-PYRIDYLAMINE DERIVATIVES

The reactivities and the site-selectivities of the hydrolyses of ATP a nd UTP by the catalysts of the metal complexes of adenine-linked di-2- pyridylamine ligands, (Py)(2)N-(CH2)(n)-Ade (L: n=3, 4, 5, and 6), wer e examined. It was found that these adenine-dipyridylamine coordinated Cu2+ complexes (with 2:1 ratios of [Cu-II(L)](2+):ATP or [Cu-II(L)](2 +):UTP) were more reactive for the hydrolyses of ATP and UTP than the complexes of ligands containing other metal ions (Mg2+ Ni2+, and Zn2+) at 40 degrees C and pH 7.3 (HEPES buffer), as reflected in much highe r product ratios of ADP/AMP and UDP/LTMP than those of Cu2+ alone. The observed high reactivity and selectivity are interpreted in terms of the base-base stackings between an adenine moiety of ATP or an uracil moiety of UTP and an adenine of the ligands, and of the selective coor dination of Cu2+ to oxide ions in phosphate residues in the ternary co mplexes of ligand-Cu2+-ATP. The Cu2+-complex of di-2-pyridylamine havi ng no adenine moiety, which is the active center of [Cu-II(L)](2+), pr omoted the hydrolyses of ATP and UTP less efficiently than the aquacop per(II) ion. The number of spacer methylene groups of the ligands infl uenced the hydrolytic activity of the Cu2+-complexes of these adenine- dipyridylamine ligands. The complexes of [Cu-II(L-4)](2+) and [Cu-II(L -5)](2+) were the most reactive and site-selective for the hydrolyses of ATP and UTP, respectively.