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Thermochemical Studies of NiII and ZnII Ternary Complexes Using Ion Mobility-Mass Spectrometry
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Effective Temperature and Structural Rearrangement in Trapped Ion Mobility Spectrometry
Denis Morsa1, Emeline Hanozin1, Gauthier Eppe1
1Mass Spectrometry Laboratory, MolSys Research Unit, University of Liège, Liège 4000, Belgium.
Analytical Chemistry
|February 22, 2020
Summary
Trapped ion mobility spectrometry (TIMS) causes significant internal heating in ions, leading to fragmentation. This study quantifies this heating effect, revealing vibrational effective temperatures around 510 K during TIMS analysis.
Area of Science:
- Analytical Chemistry
- Physical Chemistry
- Biophysical Chemistry
Background:
- Ion mobility spectrometry (IMS) is a powerful technique for analyzing biomolecules.
- High electric fields in modern IMS can induce ion activation, leading to structural changes or fragmentation.
- Understanding ion internal energy is crucial for accurate conformational analysis.
Purpose of the Study:
- To quantitatively assess the internal heating of ions during trapped ion mobility spectrometry (TIMS).
- To determine the vibrational effective temperature (Teff,vib) experienced by ions in TIMS.
- To evaluate the impact of ion heating on the structural integrity and conformational analysis of biomolecules.
Main Methods:
- Utilized benzylpyridinium "thermometer" ions to monitor fragmentation yields.
- Measured fragmentation rate constants during TIMS accumulation and analysis steps.
- Translated fragmentation data into vibrational effective temperatures (Teff,vib).
- Analyzed conformational changes in cytochrome c and lysozyme under varying TIMS conditions.
Main Results:
- Significant ion fragmentation was observed upstream and within the TIMS tunnel.
- Vibrational effective temperatures (Teff,vib) were determined to be approximately 510 K.
- Compact native folds of proteins like cytochrome c and lysozyme can be preserved.
- Collision cross section distributions are sensitive to transmission voltages and analysis timescales.
Conclusions:
- TIMS instruments can impart significant internal energy to ions, causing fragmentation.
- The measured temperatures suggest potential limitations for analyzing fragile ions or subtle conformational differences.
- Careful optimization of TIMS parameters is necessary to preserve native protein structures and obtain reliable conformational data.
- These findings are relevant for native mass spectrometry and exploring molecular conformational landscapes.
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