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Induced fit activity-based sensing: a mechanistic study of pyrophosphate detection with a “flexible” Fe-salen complex


Yadav, Prerna; Blacque, Olivier; Roodt, Andreas; Zelder, Felix (2021). Induced fit activity-based sensing: a mechanistic study of pyrophosphate detection with a “flexible” Fe-salen complex. Inorganic Chemistry Frontiers, 8(19):4313-4323.

Abstract

Activity-based sensing of biological targets is attracting increasing attention. In this work, we report detailed UV-Vis and fluorescence mechanistic studies on an Fe-salen based probe, [FeIII{salenMeCl2(SO3)2}OH2]− for pyrophosphate (PPi) detection. In the presence of PPi as an analyte, the probe disassembles into its molecular subunits and releases a fluorescent signal. Our studies illustrate that the aqua form of the complex (1-OH2) is the active species and that upon substitution of Fe-coordinated H2O and an initial end-on coordination of HP2O73−, the “trapped” pyrophosphate species switches from a monodentate to a bidentate coordination mode (i.e. linkage isomerism) via a probable equilibrium process. The elusive intermediate is further stabilized by a hydrogen bonding interaction that activates the probe for the subsequent final irreversible rate-limiting step, and allows selective discrimination between the other pyrophosphate (H2P2O72− and P2O74−) species in favour of the HP2O73−. The flexible mode of molecular recognition and binding of HP2O73− by the tetradentate probe 1-OH2 is unexpected and most effective at physiological pH, and has precedence in enzymatic catalysis (i.e. induced fit principle). These binding properties explain the previously observed outstanding selectivity of 1-OH2 for pyrophosphate over other (poly)oxophosphates and potentially competing analytes.

Abstract

Activity-based sensing of biological targets is attracting increasing attention. In this work, we report detailed UV-Vis and fluorescence mechanistic studies on an Fe-salen based probe, [FeIII{salenMeCl2(SO3)2}OH2]− for pyrophosphate (PPi) detection. In the presence of PPi as an analyte, the probe disassembles into its molecular subunits and releases a fluorescent signal. Our studies illustrate that the aqua form of the complex (1-OH2) is the active species and that upon substitution of Fe-coordinated H2O and an initial end-on coordination of HP2O73−, the “trapped” pyrophosphate species switches from a monodentate to a bidentate coordination mode (i.e. linkage isomerism) via a probable equilibrium process. The elusive intermediate is further stabilized by a hydrogen bonding interaction that activates the probe for the subsequent final irreversible rate-limiting step, and allows selective discrimination between the other pyrophosphate (H2P2O72− and P2O74−) species in favour of the HP2O73−. The flexible mode of molecular recognition and binding of HP2O73− by the tetradentate probe 1-OH2 is unexpected and most effective at physiological pH, and has precedence in enzymatic catalysis (i.e. induced fit principle). These binding properties explain the previously observed outstanding selectivity of 1-OH2 for pyrophosphate over other (poly)oxophosphates and potentially competing analytes.

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Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Chemistry
Dewey Decimal Classification:540 Chemistry
Scopus Subject Areas:Physical Sciences > Inorganic Chemistry
Language:English
Date:8 June 2021
Deposited On:07 Jul 2021 12:48
Last Modified:26 Mar 2024 02:37
Publisher:Royal Society of Chemistry
ISSN:2052-1553
OA Status:Hybrid
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.1039/d1qi00209k
Project Information:
  • : FunderSNSF
  • : Grant ID200021_169216
  • : Project TitleA stimuli responsive disassembly strategy as versatile tool for analytical applications
  • Content: Published Version
  • Licence: Creative Commons: Attribution-NonCommercial 3.0 Unported (CC BY-NC 3.0)