Revealing the Structure of Tryptophan in Microhydrated Complexes by Cold Ion Spectroscopy
The Journal of Physical Chemistry Letters
|June 23, 2023
Summary
Even a few water molecules can preserve the native structure of protonated tryptophan (TrpH+). This finding bridges gas-phase spectroscopy and biologically relevant solution structures, crucial for understanding biomolecules.
Area of Science:
- Biophysical Chemistry
- Structural Biology
- Spectroscopy
Background:
- Biomolecule structures in the gas phase often differ from their native aqueous solution forms.
- Intermolecular hydrogen bonds are critical for shaping biomolecule structures in water.
- Cold ion spectroscopy offers high resolution for gas-phase studies.
Purpose of the Study:
- To investigate the structural relevance of gas-phase biomolecule studies.
- To connect gas-phase spectroscopy with the role of water in biomolecular structure.
- To study protonated tryptophan microhydrated by 1-6 water molecules.
Main Methods:
- Infrared/Ultraviolet (IR/UV) spectroscopy
- Soft dehydration and cryogenic condensation methods
- Quantum chemistry computations
Main Results:
- Identical IR/UV spectra for complexes of the same size produced by different methods, indicating no kinetic trapping.
- Unambiguous assignment of spectra to stable conformers using quantum chemistry.
- Four water molecules are sufficient to retain most native structural features of protonated tryptophan.
Conclusions:
- Gas-phase studies of microhydrated biomolecules can accurately reflect native solution structures.
- The hydration shell plays a crucial role in maintaining biomolecular conformation.
- This work validates the use of gas-phase spectroscopy for studying biologically relevant biomolecular structures.
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