Abstract
The reactivity of polyoxovanadates towards adenosine-5′-triphosphate (ATP) hydrolysis at pH 2, 4, 6 and 7 is reported. Detailed kinetic investigation of ATP hydrolysis in the presence of polyoxovanadates was performed through multinuclear nuclear magnetic resonance (NMR) spectroscopy. In general, rate acceleration of up to five orders of magnitude was observed in the presence of vanadates compared to spontaneous ATP hydrolysis, with the greatest acceleration observed for reactions carried out at pH 2. Interestingly, the effectiveness of vanadates in promoting ATP hydrolysis decreased as the pH of the reaction solution increased; nevertheless, at pH = 7, the rate increase of one order of magnitude in comparison to blank reactions was still observed. Interactions between vanadate species in solution and ATP were investigated by means of 31P and 51V NMR spectroscopy, and this pointed towards the preferential interaction of vanadium with the phosphate groups rather than other regions of the ATP molecule.
Highlights
The bioactivity and medicinal chemistry of polyoxometalates are of great interest for the development of inorganic-based drugs, given their stability in physiological conditions, great structural variability and versatile properties [1,2,3,4,5,6]
The effectiveness of vanadates in promoting adenosine-5 -triphosphate (ATP) hydrolysis decreased as the pH of the reaction solution increased, and at pH = 7, the presence of vanadates sped up hydrolysis by only one order of magnitude in comparison to blank reactions
A marked pH effect on the reactivity was detected as larger rate accelerations were obtained for reactions conducted at lower pH values. This trend suggests that decavanadate species, which are predominant in acidic conditions, are more hydrolytically active towards ATP than cyclic tetra- and pentavanadate species dominant in neutral conditions
Summary
The bioactivity and medicinal chemistry of polyoxometalates are of great interest for the development of inorganic-based drugs, given their stability in physiological conditions, great structural variability and versatile properties [1,2,3,4,5,6]. Various divalent metal ions such as Cu2+, Zn2+, Mn2+ and Cd2+ have been reported to catalyze ATP dephosphorylation, including valuable investigations to clarify the mechanism of metal-promoted ATP hydrolysis [17,18,19,20] Most of these reactions were performed at high temperatures of up to 80 ◦C. Fitting these plots to Equations (5)–(7) of the main text affords rate constants. Initnia.ldc.oncentration of 0A.T1P3 was 20 mM, wh0i.c1h7means that, for c0o.4n3ditions featuring0V.4130,
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