POTENTIOMETRIC AND SPECTROSCOPIC STUDIES ON THE TERNARY COMPLEXES OF COPPER(II) WITH DIPEPTIDES AND NUCLEOBASES

Ternary complexes of copper(II) with dipeptides (GlyGly, GlyAsp, and M etVal) and nucleobases (MeC, MeA, MeUH, MeTH, EtGH, uridine, and thymi dine) or derivatives of amino acids (Ac-Lys and Ac-Hm) were studied by potentiometric, UV-visible, and EPR spectroscopic methods. It was fou nd that all ligands form stable adducts with the CnAH(-1) species of d ipeptides, and the ternary complexes formed by the coordination of imi dazole nitrogen donor atom are the most favored in the physiological p H range. The formation of a dimeric species Cu(2)A(2)H(-2)B was detect ed in the case of EtGH supporting that both N1 and N7 nitrogens of pur ine take part in metal ion coordination. The data of spectroscopic mea surements supported the equatorial coordination of nitrogen donors in CuABH(-1) ternary complexes. (C) 1997 Elsevier Science Inc.