Studies of the binding of chromium(III) complexes to phosphate groups of adenosine triphosphate

The binding of a number of chromium complexes to ATP has been studied by 31P NMR spectroscopy. The results are consistent with the formation of outer-sphere complexes between ATP and the chromium species. The magnitude of the binding constant has been determined as approximately 500 mol-1 dm3 (pH = 7.00) for the interaction of trisethylenediamine chromium(III) with ATP. Under our experimental conditions no NMR signals are observed from complexes in which chromium(III) is bound directly to the phosphate groups of ATP. The relative stability of the inner sphere complexes of chromium(III) and glutathione or ATP is probably not a significant factor in determining the toxicity of chromium(III) complexes.