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Probing Local Electrostatics of Glycine in Aqueous Solution by THz Spectroscopy.

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 pK_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.

SUBMITTER: Sebastiani F

PROVIDER: S-EPMC7898531 | biostudies-literature | 2021 Feb

REPOSITORIES: biostudies-literature

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Probing Local Electrostatics of Glycine in Aqueous Solution by THz Spectroscopy.

Sebastiani Federico F Ma Chun Yu CY Funke Sarah S Bäumer Alexander A Decka Dominique D Hoberg Claudius C Esser Alexander A Forbert Harald H Schwaab Gerhard G Marx Dominik D Havenith Martina M

Angewandte Chemie (International ed. in English) 20201221 7

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<sup>-1</sup> 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 ...[more]

PMID: 33156972

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