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Ebbe Nordlander. Portrait.

Ebbe Nordlander

Professor

Ebbe Nordlander. Portrait.

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

Author

  • Biswanath Das
  • Henrik Daver
  • Monika Pyrkosz-Bulska
  • Elzbieta Gumienna-Kontecka
  • Fahmi Himo
  • Ebbe Nordlander

Summary, in English

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.

Department/s

  • Chemical Physics

Publishing year

2018

Language

English

Pages

3986-3986

Publication/Series

European Journal of Inorganic Chemistry

Volume

2018

Issue

36

Document type

Journal article

Publisher

John Wiley & Sons Inc.

Topic

  • Inorganic Chemistry

Keywords

  • Active sites
  • Coordination chemistry
  • Metalloenzymes
  • Phosphoester hydrolysis

Status

Published

ISBN/ISSN/Other

  • ISSN: 1434-1948