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Oxygen K-shell spectroscopy of isolated progressively solvated peptide
Aleksandar R Milosavljević1, Kari Jänkälä, Miloš Lj Ranković
1SOLEIL, l'Orme des Merisiers, St Aubin, BP48, 91192 Gif sur Yvette Cedex, France. milosavljevic@synchrotron-soleil.fr.
Physical Chemistry Chemical Physics : PCCP
|April 30, 2020
Summary
Near-edge X-ray-absorption fine structure (NEXAFS) action spectroscopy reveals that hydrated substance P (SP) ions fragment differently than bare ions. Hydrated SP shows increased fragmentation due to resonant excitation of water molecules.
Area of Science:
- Chemical Physics
- Molecular Spectroscopy
- Biophysical Chemistry
Background:
- Investigating the behavior of biomolecules in solution is crucial for understanding biological processes.
- Gas-phase studies offer a controlled environment to isolate and study molecular interactions.
- X-ray-absorption spectroscopy provides element-specific electronic structure information.
Purpose of the Study:
- To probe the fragmentation dynamics of isolated substance P (SP) molecular ions.
- To investigate the influence of water solvation on SP ion fragmentation using NEXAFS action spectroscopy.
- To explore potential nonlocal energy transfer mechanisms from water to SP.
Main Methods:
- Gas-phase near-edge X-ray-absorption fine structure (NEXAFS) action spectroscopy.
- Mass spectrometry for analyzing fragmentation patterns.
- Molecular dynamics and DFT calculations for theoretical support.
Main Results:
- Hydrated SP ions (4 and 11 water molecules) exhibit distinct fragmentation patterns compared to bare SP ions.
- Doubly protonated, hydrated SP ions show abundant doubly charged backbone fragments and preserve water clusters.
- Action NEXAFS revealed increased fragmentation in hydrated SP due to resonant excitation of water molecules, unlike collisional dissociation.
Conclusions:
- Solvation significantly alters the fragmentation pathways of SP ions under resonant X-ray excitation.
- The observed fragmentation suggests a potential for nonlocal energy transfer from water to SP.
- Further experimental investigation is warranted to elucidate solvent-biomolecule energy transfer mechanisms.
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