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Bound anions differentially stabilize multiprotein complexes in the absence of bulk solvent
Linjie Han1, Suk-Joon Hyung, Jonathan J S Mayers
1Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, USA.
Journal of the American Chemical Society
|June 17, 2011
Summary
Adding specific salts stabilizes protein structures for ion mobility-mass spectrometry. This method protects protein complexes in the gas phase, crucial for structural biology research.
Area of Science:
- Structural biology
- Biophysical chemistry
- Analytical chemistry
Background:
- Ion mobility-mass spectrometry (IM-MS) is a powerful tool for analyzing protein assemblies.
- Protein structure can be altered when removed from solution for IM-MS analysis.
- Stabilizing proteins in the gas phase is essential for accurate structural assessment.
Purpose of the Study:
- To identify and classify anions that stabilize protein structures in the gas phase.
- To understand the mechanism of anion-mediated stabilization of protein complexes.
- To compare gas-phase stabilization with solution-phase properties (Hofmeister series).
Main Methods:
- Utilized ion mobility-mass spectrometry (IM-MS) to analyze protein complexes.
- Introduced various salts (anions) to protein solutions prior to ionization.
- Applied collisional activation to observe dissociation and unfolding transitions.
- Quantified the influence of 12 different anions on gas-phase protein structure.
Main Results:
- Identified tartrate, citrate, chloride, and nitrate as strong stabilizers of gas-phase protein structure.
- Demonstrated that the rank order of stabilizers differs significantly from the solution-phase Hofmeister series.
- Established a mechanism for counterion stabilization involving high-affinity binding and ready dissociation.
- Classified anions into three categories based on their stabilization ability.
Conclusions:
- Counterion addition is an effective strategy to stabilize protein structures for gas-phase analysis.
- Gas-phase protein stabilization is influenced by both anion-protein binding and hydration effects.
- The findings provide a framework for selecting optimal anions for IM-MS studies.
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