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Probing Local Electrostatics of Glycine in Aqueous Solution by THz Spectroscopy
Author(s) -
Sebastiani Federico,
Ma Chun Yu,
Funke Sarah,
Bäumer Alexander,
Decka Dominique,
Hoberg Claudius,
Esser Alexander,
Forbert Harald,
Schwaab Gerhard,
Marx Dominik,
Havenith Martina
Publication year - 2021
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.202014133
Subject(s) - protonation , terahertz radiation , spectroscopy , terahertz spectroscopy and technology , chemistry , glycine , aqueous solution , terahertz time domain spectroscopy , electrostatics , titration , analytical chemistry (journal) , chemical physics , computational chemistry , materials science , amino acid , physics , ion , optoelectronics , organic chemistry , quantum mechanics , biochemistry
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 p K a 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.