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An Unsymmetric Ligand with a N5O2 Donor Set and Its Corresponding Dizinc Complex : A Structural and Functional Phosphoesterase Model

Das, Biswanath LU ; Daver, Henrik ; Pyrkosz-Bulska, Monika ; Gumienna-Kontecka, Elzbieta ; Himo, Fahmi and Nordlander, Ebbe LU (2018) In European Journal of Inorganic Chemistry 2018(36). p.3986-3986
Abstract

To mimic the active sites of the hydrolytic enzyme zinc phosphotriesterase, a new dinucleating unsymmetric ligand, PICIMP (2-([2-hydroxy-5-methyl-3-(([(1-methyl-1H-imidazol-2-yl)methyl](pyridin-2-ylmethyl)amino)methyl)benzyl][(1-methyl-1H-imidazol-2-yl)methyl]amino)acetic acid), has been synthesized and characterized. The hydrolytic efficacy of the complex solution (PICIMP/ZnCl2 = 1:2) has been investigated using bis-(2,4-dinitrophenyl)phosphate (BDNPP), a DNA analogue substrate. Speciation studies were undertaken by potentiometric titrations at varying pH for both the ligand and the corresponding dizinc complex to elucidate the formation of the active hydrolysis catalyst; these studies reveal that the dinuclear zinc(II)... (More)

To mimic the active sites of the hydrolytic enzyme zinc phosphotriesterase, a new dinucleating unsymmetric ligand, PICIMP (2-([2-hydroxy-5-methyl-3-(([(1-methyl-1H-imidazol-2-yl)methyl](pyridin-2-ylmethyl)amino)methyl)benzyl][(1-methyl-1H-imidazol-2-yl)methyl]amino)acetic acid), has been synthesized and characterized. The hydrolytic efficacy of the complex solution (PICIMP/ZnCl2 = 1:2) has been investigated using bis-(2,4-dinitrophenyl)phosphate (BDNPP), a DNA analogue substrate. Speciation studies were undertaken by potentiometric titrations at varying pH for both the ligand and the corresponding dizinc complex to elucidate the formation of the active hydrolysis catalyst; these studies reveal that the dinuclear zinc(II) complexes, [Zn2(PICIMP)]2+ and [Zn2(PICIMP)(OH)]+ predominate in solution above pH 4. The obtained pKa of 7.44 for the deprotonation of water suggests formation of a bridging hydroxide between the two ZnII ions. Kinetic investigations of BDNPP hydrolysis over the pH range 5.5-10.5 have been performed. The cumulative results indicate the hydroxo-bridged dinuclear ZnII complex [Zn2(PICIMP)(μ-OH)]+ as the effective catalyst. Density functional theory calculations were performed to investigate the detailed reaction mechanism. The calculations suggest that the bridging hydroxide becomes terminally coordinated to one of the zinc ions before performing the nucleophilic attack in the reaction.

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author
; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Active sites, Coordination chemistry, Metalloenzymes, Phosphoester hydrolysis
in
European Journal of Inorganic Chemistry
volume
2018
issue
36
pages
3986 - 3986
publisher
John Wiley & Sons Inc.
external identifiers
  • scopus:85047737484
  • scopus:85054128171
ISSN
1434-1948
DOI
10.1002/ejic.201701416
language
English
LU publication?
yes
id
9c46739f-362d-48c0-b09c-238ac56bf0a1
date added to LUP
2018-06-15 15:20:37
date last changed
2021-10-06 04:15:34
@article{9c46739f-362d-48c0-b09c-238ac56bf0a1,
  abstract     = {<p>To mimic the active sites of the hydrolytic enzyme zinc phosphotriesterase, a new dinucleating unsymmetric ligand, PICIMP (2-([2-hydroxy-5-methyl-3-(([(1-methyl-1H-imidazol-2-yl)methyl](pyridin-2-ylmethyl)amino)methyl)benzyl][(1-methyl-1H-imidazol-2-yl)methyl]amino)acetic acid), has been synthesized and characterized. The hydrolytic efficacy of the complex solution (PICIMP/ZnCl<sub>2</sub> = 1:2) has been investigated using bis-(2,4-dinitrophenyl)phosphate (BDNPP), a DNA analogue substrate. Speciation studies were undertaken by potentiometric titrations at varying pH for both the ligand and the corresponding dizinc complex to elucidate the formation of the active hydrolysis catalyst; these studies reveal that the dinuclear zinc(II) complexes, [Zn<sub>2</sub>(PICIMP)]<sup>2+</sup> and [Zn<sub>2</sub>(PICIMP)(OH)]<sup>+</sup> predominate in solution above pH 4. The obtained pK<sub>a</sub> of 7.44 for the deprotonation of water suggests formation of a bridging hydroxide between the two Zn<sup>II</sup> ions. Kinetic investigations of BDNPP hydrolysis over the pH range 5.5-10.5 have been performed. The cumulative results indicate the hydroxo-bridged dinuclear Zn<sup>II</sup> complex [Zn<sub>2</sub>(PICIMP)(μ-OH)]<sup>+</sup> as the effective catalyst. Density functional theory calculations were performed to investigate the detailed reaction mechanism. The calculations suggest that the bridging hydroxide becomes terminally coordinated to one of the zinc ions before performing the nucleophilic attack in the reaction.</p>},
  author       = {Das, Biswanath and Daver, Henrik and Pyrkosz-Bulska, Monika and Gumienna-Kontecka, Elzbieta and Himo, Fahmi and Nordlander, Ebbe},
  issn         = {1434-1948},
  language     = {eng},
  number       = {36},
  pages        = {3986--3986},
  publisher    = {John Wiley & Sons Inc.},
  series       = {European Journal of Inorganic Chemistry},
  title        = {An Unsymmetric Ligand with a N<sub>5</sub>O<sub>2</sub> Donor Set and Its Corresponding Dizinc Complex : A Structural and Functional Phosphoesterase Model},
  url          = {http://dx.doi.org/10.1002/ejic.201701416},
  doi          = {10.1002/ejic.201701416},
  volume       = {2018},
  year         = {2018},
}