Structural, kinetic, and theoretical studies on models of the zinc-containing phosphodiesterase active center: medium-dependent reaction mechanisms |
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Authors: | Selmeczi Katalin Michel Carine Milet Anne Gautier-Luneau Isabelle Philouze Christian Pierre Jean-Louis Schnieders David Rompel Annette Belle Catherine |
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Institution: | Département de Chimie Moléculaire, Université J. Fourier, Grenoble I, UMR-5250, ICMG FR-2607, CNRS BP-53, 38041 Grenoble, France. |
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Abstract: | Dinuclear zinc(II) complexes Zn(2)(bpmp)(mu-OH)](ClO(4))(2) (1) and Zn(2)(bpmp)(H(2)O)(2)](ClO(4))(3) (2) (H-BPMP=2,6-bisbis(2-pyridylmethyl)aminomethyl]-4-methylphenol) have been synthesized, structurally characterized, and pH-driven changes in metal coordination observed. The transesterification reaction of 2-hydroxypropyl p-nitrophenyl phosphate (HPNP) in the presence of the two complexes was studied both in a water/DMSO (70:30) mixture and in DMSO. Complex 2 was not reactive whereas for 1 considerable rate enhancement of the spontaneous hydrolysis reaction was observed. A detailed mechanistic investigation by kinetic studies, spectroscopic measurements ((1)H, (31)P NMR spectroscopy), and ESI-MS analysis in conjunction with ab initio calculations was performed on 1. Based on these results, two medium-dependent mechanisms are presented and an unusual bridging phosphate intermediate is proposed for the process in DMSO. |
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Keywords: | ab initio calculations bioinorganic chemistry phosphodiesters reaction mechanisms zinc |
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