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Catalytic Hydrolysis of Adenosine Triphosphate (ATP) by Antitumoral ϵ‐Keggin Core Compound, [H 2 Mo V 12 O 28 (OH) 12 (Mo VI O 3 ) 4 ] 6– , at pH 5 and 7.5
Author(s) -
Ishikawa Eri,
Yamase Toshihiro
Publication year - 2013
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201201164
Subject(s) - chemistry , atp hydrolysis , hydrolysis , adenosine triphosphate , isothermal titration calorimetry , electrospray ionization , medicinal chemistry , adenosine monophosphate , phosphate , inorganic chemistry , stereochemistry , nuclear chemistry , adenosine , mass spectrometry , organic chemistry , biochemistry , chromatography , enzyme , atpase
The hydrolysis of adenosine triphosphate (ATP) [to adenosine diphosphate (ADP) and phosphate] at 40 °C by [Me 3 NH] 6 [H 2 Mo V 12 O 28 (OH) 12 (Mo VI O 3 ) 4 ] · 2H 2 O (PM‐17) as an important candidate for antitumor chemotherapy is investigated with the help of 31 P NMR spectroscopy, electrospray ionization mass spectrometry (ESI‐MS), and isothermal titration calorimetry (ITC). The ATP hydrolysis at pH 5 and 7.5 proceeds catalytically to yield ADP, H n PO 4 (3– n )– , adenosine monophosphate (AMP), and [(PO 4 ) 2 Mo 5 O 15 ] 6– . AMP and [(PO 4 ) 2 Mo 5 O 15 ] 6– result from the secondary step of the ATP hydrolysis: the former was produced by the hydrolysis of ADP (with the liberation of phosphate), and the latter by the condensation among phosphates and monomolybdates (derived from the partial release of the Mo VI O 3 moieties from the PM‐17 anion). The enhancement of the ATP hydrolysis in the presence of K + is discussed in terms of the electrostatic interaction of K + at the P γ phosphate in the negatively charged ATP 5′‐triphosphates, which accompanies the coordination of PM‐17 anions with a resultant conformational constraint of this phosphate. Values of thermodynamic parameters for the interaction between ATP and PM‐17 at pH 7.5 suggest the K + ‐mediated assembly of PM‐17 anions at the 5′‐triphosphate chain (matrix effect), which leads to a decrease in the ATP hydrolysis owing to the depressed activation of the P γ –O–P β linkage.