TERNARY COMPLEX-FORMATION BETWEEN AL(III)-ADENOSINE-5'-PHOSPHATES ANDCARBOXYLIC-ACID DERIVATIVES

The possibility of ternary complex formation has been studied in the A l(III)-adenosine-5'-phosphate (AMP, ADP, and ATP)-ligand B (oxalic aci d, lactic acid, and malic acid) systems by pH-potentiometric and P-31 NMR methods. Formation of ternary complexes AlABH and AlAB is favored in all systems in the acidic pH range. Under physiological conditions at mu molar Al3+ concentrations and at high ligand excess, Al(III) is bound mainly to the nucleotides: almost exclusively in the presence of the relatively weak bidentate Al(III) binder oxalic acid and lactic a cid, and about 30% in the presence of the much stronger tridentate-coo rdinating molecule, malic acid.