NDLI: Kinetic studies of phosphoester hydrolysis promoted by a dimeric tetrazirconium(IV) Wells

Content Provider	World Health Organization (WHO)-Global Index Medicus
Author	Shestakova, Pavletta Luong, Thi Kim Nga Parac-vogt, Tatjana N.
Description	Author Affiliation: Luong TK ( Department of Chemistry, KU Leuven, Celestijnenlaan 200F, 3001 Leuven, Belgium. Tatjana.Vogt@chem.kuleuven.be.); Shestakova P ( NMR Laboratory, Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Acad. G. Bontchev Str., Bl.9, 1113 Sofia, Bulgaria.); Parac-Vogt TN ( Department of Chemistry, KU Leuven, Celestijnenlaan 200F, 3001 Leuven, Belgium. Tatjana.Vogt@chem.kuleuven.be.)
Abstract	The catalytic hydrolysis of a phosphoester bond in the DNA-model substrate 4-nitrophenyl phosphate (NPP) promoted by Zr(IV)-substituted Wells–Dawson $Na_{14}[Zr_{4}(P_{2}W_{16}O_{59})_{2}(μ_{3}-O)_{2}(OH)_{2}(H_{2}O)_{4}]·57H_{2}O$ polyoxometalate (ZrWD 4:2) was followed by means of $^{1}H$ and $^{31}P$ NMR spectroscopy. The hydrolytic reaction proceeded with a rate constant of 8.44 (±0.36) × $10^{−5}$ $s^{−1}$ at pD 6.4 and 50 °C, representing a 300-fold rate enhancement in comparison with the spontaneous hydrolysis of NPP $(k_{obs}$ = 2.81 (±0.25) × $10^{−7}$ $s^{−1})$ under the same reaction conditions. The ZrWD 4:2 was also active towards hydrolysis of bis(4-nitrophenyl) phosphate (BNPP) and the RNA model substrate 2-hydroxypropyl-4-nitrophenyl phosphate (HPNP). The pD dependence of $k_{obs}$ shows that the rate constants for NPP hydrolysis decrease significantly when the pD values of the reaction mixtures increase. The formation constant $(K_{f}$ = 190 $M^{−1})$ and catalytic rate constant $(k_{c}$ = 6.40 × $10^{−4}$ $s^{−1})$ for the NPP-ZrWD 4:2 complex, activation energy $(E_{a})$ of 110.15 ± 7.06 kJ $mol^{−1},$ enthalpy of activation $(ΔH^{‡})$ of 109.03 ± 6.86 kJ $mol^{−1},$ entropy of activation $(ΔS^{‡})$ of 15.20 ± 2.49 J $mol^{−1}$ $K^{−1},$ and Gibbs activation energy $(ΔG^{‡})$ of 104.32 ± 6.09 kJ $mol^{−1}$ at 37 °C were calculated from kinetic studies. The recyclability of ZrWD 4:2 was examined by adding an extra amount (5.0 mM) of NPP twice to a fully hydrolyzed mixture of 5.0 mM NPP and 1.0 mM ZrWD 4:2. The interaction between ZrWD 4:2 and the P–O bond of NPP was evidenced by a change in the $^{31}P$ chemical shift of the $^{31}P$ atom in NPP upon addition of ZrWD 4:2. Based on $^{31}P$ NMR experiments and the kinetic studies, a mechanism for NPP hydrolysis promoted by ZrWD 4:2 has been proposed.
ISSN	14779226
Issue Number	30
Journal	Dalton Trans.
Volume Number	45
e-ISSN	13645447
Language	English
Publisher	Royal Society of Chemistry
Publisher Date	2016-07-26
Publisher Place	Great Britain (UK)
Access Restriction	Subscribed
Subject Keyword	Chemistry
Content Type	Text
Resource Type	Article
Subject	Inorganic Chemistry

Sl.	Authority	Responsibilities	Communication Details
1	Ministry of Education (GoI), Department of Higher Education	Sanctioning Authority	https://www.education.gov.in/ict-initiatives
2	Indian Institute of Technology Kharagpur	Host Institute of the Project: The host institute of the project is responsible for providing infrastructure support and hosting the project	https://www.iitkgp.ac.in
3	National Digital Library of India Office, Indian Institute of Technology Kharagpur	The administrative and infrastructural headquarters of the project	Dr. B. Sutradhar bsutra@ndl.gov.in
4	Project PI / Joint PI	Principal Investigator and Joint Principal Investigators of the project	Dr. B. Sutradhar bsutra@ndl.gov.in Prof. Saswat Chakrabarti will be added soon
5	Website/Portal (Helpdesk)	Queries regarding NDLI and its services	support@ndl.gov.in
6	Contents and Copyright Issues	Queries related to content curation and copyright issues	content@ndl.gov.in
7	National Digital Library of India Club (NDLI Club)	Queries related to NDLI Club formation, support, user awareness program, seminar/symposium, collaboration, social media, promotion, and outreach	clubsupport@ndl.gov.in
8	Digital Preservation Centre (DPC)	Assistance with digitizing and archiving copyright-free printed books	dpc@ndl.gov.in
9	IDR Setup or Support	Queries related to establishment and support of Institutional Digital Repository (IDR) and IDR workshops	idr@ndl.gov.in