New Amino-Acid-Based β-Phosphorylated Nitroxides for Probing Acidic pH in Biological Systems by EPR Spectroscopy

Sophie Thétiot-Laurent, Gaëlle Gosset, Jean Louis Clément, Mathieu Cassien, Anne Mercier, Didier Siri, Anouk Gaudel-Siri, Antal Rockenbauer, Marcel Culcasi, Sylvia Pietri

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3 Citations (Scopus)

Abstract

There is increasing interest in measuring pH in biological samples by using nitroxides with pH-dependent electron paramagnetic resonance (EPR) spectra. Aiming to improve the spectral sensitivity (ΔaX) of these probes (i.e., the difference between the EPR hyperfine splitting (hfs) in their protonated and unprotonated forms), we characterized a series of novel linear α-carboxy, α′-diethoxyphosphoryl nitroxides constructed on an amino acid core and featuring an (α or α′)-C−H bond. In buffer, the three main hfs (aN, aH, and aP) of their EPR spectra vary reversibly with pH and, from aP or aH titration curves, a two- to fourfold increase in sensitivity was achieved compared to reference imidazoline or imidazolidine nitroxides. The crystallized carboxylate 10 b (pKa ≈3.6), which demonstrated low cytotoxicity and good resistance to bioreduction, was applied to probe stomach acidity in rats. The results pave the way to a novel generation of highly sensitive EPR pH markers.

Original languageEnglish
Pages (from-to)300-315
Number of pages16
JournalChemBioChem
Volume18
Issue number3
DOIs
Publication statusPublished - Feb 1 2017

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Keywords

  • EPR spectroscopy
  • molecular dynamics
  • nitroxide
  • sensors
  • stomach acidity

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Medicine
  • Molecular Biology
  • Organic Chemistry

Cite this

Thétiot-Laurent, S., Gosset, G., Clément, J. L., Cassien, M., Mercier, A., Siri, D., Gaudel-Siri, A., Rockenbauer, A., Culcasi, M., & Pietri, S. (2017). New Amino-Acid-Based β-Phosphorylated Nitroxides for Probing Acidic pH in Biological Systems by EPR Spectroscopy. ChemBioChem, 18(3), 300-315. https://doi.org/10.1002/cbic.201600550