P. Venkataiah et al., EQUILIBRIUM STUDIES ON TERNARY CU(II) COMPLEXES CONTAINING ADENOSINE-5'-TRIPHOSPHATE, Proceedings of the Indian Academy of Sciences. Chemical sciences, 106(4), 1994, pp. 813-818
Interaction of adenosine-5'-triphosphate (ATP) with a series of binary
Cu(II) complexes (ML) (where L=o-phenanthroline (Phen), 5-nitrophenan
throline (NPhen), 5-methyl phenanthroline (MPhen), 2,9-dimethylphenant
hroline (DPhen), 2,9-dimethyl-4,7-diphenylphenanthroline (DPhPhen), 2,
2'-bipyridyl (Bipy), bis(imidazol-2-yl) methane (BIM), oxalic acid (Ox
), glycine (Gly), alanine (Ala), valine (Val), phenylalanine (Phe), tr
yptophan (Trp), methionine (Met), histidine (His) or aspartic acid (As
p) to form ternary complexes (MLA) was investigated by a pH-metric tec
hnique and the formation constants were evaluated at 35.0 degrees C an
d mu = 0.2 M (KNO3). The influence exerted by ligand L on the binding
of ATP to Cu(II) was quantitatively assessed and ATP was found to bind
more strongly when L = bidentate nitrogen donors, relatively less str
ongly when L = amino acids and least strongly when L = a bidentate oxy
gen donor. With respect to the nitrogen donor ligands the stability of
the ternary complexes decreases in the order NPhen > Phen > Bipy > MP
hen > DPhen > BIM approximate to DPhPhen, whereas in ternary complexes
containing amino acids the stability decreases in the order: Phe appr
oximate to Trp > Ala > Gly approximate to Val approximate to Met > His
> Asp. The trends in the stability of the various complexes are discu
ssed in terms of the nature of the metal ion and the two ligands in it
s coordination sphere.