Structures of ATP(adenosine triphosphate)-vanadyl complexes.

The state of existence of cytoplasmic vanadium ion is known to be important: vanadyl ion forms complexes with ATP and vanadate form inhibits (Na++K+)-ATPase. Therefore, the formation of complexes between ATP and vanadyl ion was investigated. Formations of three types of complex were observed: a blue 1:1 complex formed in acidic pH region; a blue 1:1 complex formed in neutral pH region; a green 2:1 complex formed in alkaline pH region. On the basis of the results on potentiometric titration, optical and EPR spectra and 31P- and 13C-NMR spectra, three characteristic types of coordination environment are proposed.