Based upon precise terahertz (THz) measurements of the solvated amino acid glycine and accompanying ab-initio molecular-dynamics simulations, we show that the N-C-C-O open/close mode at 315 cm−1 serves as a sensitive, label-free probe for the local protonation of the amide group. Experimentally, we can show that this holds not only for glycine but also for diglycine and valine. The approach is more general, since the changes due to protonation result in intensity changes which can be probed by THz time domain (0–50 cm−1) as well as by precise THz-FT spectroscopy (50–400 cm−1). A detailed analysis allows us to directly correlate the titration spectra with pKa values. This demonstrates the potential of THz spectroscopy to probe the charge state of a natural amino acid in water in a label-free manner.

Probing Local Electrostatics of Glycine in Aqueous Solution by THz Spectroscopy / Sebastiani F.; Ma C.Y.; Funke S.; Baumer A.; Decka D.; Hoberg C.; Esser A.; Forbert H.; Schwaab G.; Marx D.; Havenith M.. - In: ANGEWANDTE CHEMIE. INTERNATIONAL EDITION. - ISSN 1433-7851. - STAMPA. - 60:(2021), pp. 3768-3772. [10.1002/anie.202014133]

Probing Local Electrostatics of Glycine in Aqueous Solution by THz Spectroscopy

Sebastiani F.;
2021

Abstract

Based upon precise terahertz (THz) measurements of the solvated amino acid glycine and accompanying ab-initio molecular-dynamics simulations, we show that the N-C-C-O open/close mode at 315 cm−1 serves as a sensitive, label-free probe for the local protonation of the amide group. Experimentally, we can show that this holds not only for glycine but also for diglycine and valine. The approach is more general, since the changes due to protonation result in intensity changes which can be probed by THz time domain (0–50 cm−1) as well as by precise THz-FT spectroscopy (50–400 cm−1). A detailed analysis allows us to directly correlate the titration spectra with pKa values. This demonstrates the potential of THz spectroscopy to probe the charge state of a natural amino acid in water in a label-free manner.
2021
60
3768
3772
Sebastiani F.; Ma C.Y.; Funke S.; Baumer A.; Decka D.; Hoberg C.; Esser A.; Forbert H.; Schwaab G.; Marx D.; Havenith M.
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Utilizza questo identificatore per citare o creare un link a questa risorsa: https://hdl.handle.net/2158/1288134
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