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Conformations of gas-phase lysozyme ions produced from two different solution conformations
Dunmin Mao1, Kodali Ravindra Babu, Yu-Luan Chen
1Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada.
Analytical Chemistry
|March 28, 2003
Summary
Lysozyme protein ions generated from native and denatured states show similar gas-phase structures. This suggests that denatured proteins can refold into compact forms in the gas phase, challenging common assumptions in mass spectrometry.
Area of Science:
- Protein chemistry
- Mass spectrometry
- Biophysical characterization
Background:
- Lysozyme exhibits native conformation in water near pH 2.0.
- In water/methanol mixtures, lysozyme adopts a helical denatured conformation.
- Hydrogen/deuterium exchange confirms partial unfolding in the water/methanol solution.
Purpose of the Study:
- To investigate the gas-phase conformations of lysozyme ions.
- To compare ions derived from native and denatured solution states.
- To explore the refolding behavior of denatured proteins in the gas phase.
Main Methods:
- Electrospray ionization (ESI) mass spectrometry (MS) for ion generation.
- Hydrogen/deuterium (H/D) exchange to probe ion structure.
- Cross section measurements to determine ion dimensions.
Main Results:
- Lysozyme ions from native and denatured states exhibit similar charge state distributions.
- Gas-phase H/D exchange and cross section measurements indicate comparable ion structures.
- Ions possess compact structures, suggesting rapid gas-phase refolding.
Conclusions:
- Lysozyme is an exception to the rule of higher charge states for denatured proteins.
- Gas-phase ions derived from different solution conformations can be directly compared.
- Disulfide-intact lysozyme ions refold into compact structures in the gas phase within milliseconds.