Issue 34, 2016

Chiral sensing of amino acids and proteins chelating with EuIII complexes by Raman optical activity spectroscopy

Abstract

Chiroptical spectroscopy of lanthanides sensitively reflects their environment and finds various applications including probing protein structures. However, the measurement is often hampered by instrumental detection limits. In the present study circularly polarized luminescence (CPL) of a europium complex induced by amino acids is monitored by Raman optical activity (ROA) spectroscopy, which enables us to detect weak CPL bands invisible to conventional CPL spectrometers. In detail, the spectroscopic response to the protonation state could be studied, e.g. histidine at pH = 2 showed an opposite sign of the strongest CPL band in contrast to that at pH = 7. The spectra were interpreted qualitatively on the basis of the ligand-field theory and related to CPL induced by an external magnetic field. Free energy profiles obtained by molecular dynamic simulations for differently charged alanine and histidine forms are in qualitative agreement with the spectroscopic data. The sensitivity and specificity of the detection promise future applications in probing peptide and protein side chains, chemical imaging and medical diagnosis. This potential is observed for human milk and hen egg-white lysozymes; these proteins have a similar structure, but very different induced CPL spectra.

Graphical abstract: Chiral sensing of amino acids and proteins chelating with EuIII complexes by Raman optical activity spectroscopy

Associated articles

Supplementary files

Article information

Article type
Paper
Submitted
07 Jun 2016
Accepted
01 Aug 2016
First published
01 Aug 2016
This article is Open Access
Creative Commons BY license

Phys. Chem. Chem. Phys., 2016,18, 23803-23811

Chiral sensing of amino acids and proteins chelating with EuIII complexes by Raman optical activity spectroscopy

T. Wu, J. Kessler and P. Bouř, Phys. Chem. Chem. Phys., 2016, 18, 23803 DOI: 10.1039/C6CP03968E

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