The formation of ATP analogue, ADPV and the binding of paramagnetic Mn^2^+ to ADPV were studied in detail by ^5^1V NMR method in aqueous solution and the pH close to physiological condition. The polymerization of vanadate was found to decrease with decreasing ionic strength. The results show that the reactions occur between monomeric or dimeric vanadate and ADP in two different ways leading to the formation of an ATP analogue-ADPV with vanadate in the tetrahedral monomeric form and at higher concentration of ADP, a binuclear vanadate complex, in which vanadate bind simultaneously with the 2' and 3'-hydroxyl groups of the ribose ring. Their equilibrium constants of formation reactions were obtained. The ^5^1V NMR spectra changes significantly on the addition of paramagnetic Mn^2^+ into aqueous solution of vanadate and ADP. Based on the spectra it was indicated that the β-phosphate and γ-vanadate of ADPV chelate Mn^2^+ simultaneously with the formation of a Mg^2^+-ATP analogue, Mn^2^+- ADPV.

Key words: MAGNESIUM ION, EQUILIBRIUM CONSTANT, VANADIC ACID, ADENOSINE DIPHOSPHATE