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Updated: Aug 6, 2026

High-Pressure NMR Experiments for Detecting Protein Low-Lying Conformational States
Published on: June 29, 2021
NMR spectroscopic study of noble gas binding into the engineered cavity of HPr(I14A) from Staphylococcus carnosus
Lydia Nisius1, Max Stadler, Hans Robert Kalbitzer
1Institute of Biophysics and Physical Biochemistry, University of Regensburg, D-93040 Regensburg, Germany.
Abstract:
Xenon binding into preexisting cavities in proteins is a well-known phenomenon. Here we investigate the interaction of helium, neon, and argon with hydrophobic cavities in proteins by NMR spectroscopy. 1H and 15N chemical shifts of the I14A mutant of the histidine-containing phosphocarrier protein (HPr(I14A)) from Staphylococcus carnosus are analyzed by chemical shift mapping. Total noble gas induced chemical shifts, Delta, are calculated and compared with the corresponding values obtained using xenon as a probe atom. This comparison reveals that the same cavity is detected with both argon and xenon. Measurements using the smaller noble gases helium and neon as probe atoms do not result in comparable effects. The dependence of amide proton and nitrogen chemical shifts on the argon concentration is investigated in the range from 10 mM up to 158 mM. The average dissociation constant for argon binding into the engineered cavity is determined to be about 90 mM.
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