Related Experiment Videos
Diffusion measurements by electrospray mass spectrometry for studying solution-phase noncovalent interactions
Sonya M Clark1, Lars Konermann
1Department of Chemistry, The University of Western Ontario, London, Ontario, Canada.
Summary
This study introduces a new method using electrospray mass spectrometry (ESI-MS) to monitor noncovalent interactions by measuring analyte diffusion. The technique successfully detected heme-protein binding in myoglobin under various conditions.
Area of Science:
- Analytical Chemistry
- Biochemistry
- Physical Chemistry
Background:
- Monitoring noncovalent interactions in solution is crucial for understanding biological processes.
- Conventional methods often rely on preserving solution-phase interactions in the gas phase, which can be challenging.
- Electrospray mass spectrometry (ESI-MS) is a powerful tool for analyzing biomolecules, but its application to noncovalent interactions has limitations.
Purpose of the Study:
- To develop and validate a novel ESI-MS-based approach for monitoring noncovalent interactions in solution.
- To assess the influence of solution conditions (pH, solvent composition) on noncovalent complex stability.
- To demonstrate the technique's applicability using heme-protein interactions in myoglobin.
Main Methods:
- Utilized Taylor dispersion analysis in a laminar flow tube to measure analyte diffusion coefficients.
- Employed electrospray mass spectrometry (ESI-MS) to monitor dispersion profiles of interacting species.
- Applied "harsh" ion source conditions to ensure separate monitoring of diffusion profiles, independent of gas-phase interactions.
Main Results:
- Demonstrated that similar diffusion profiles indicate noncovalent complex formation, while dissimilar profiles suggest dissociation.
- Successfully observed tight noncovalent heme-myoglobin binding at pH 10, even with 30% acetonitrile.
- Showed disruption of noncovalent interactions at 50% acetonitrile and pH 2.4, correlating with known conformational changes in myoglobin.
Conclusions:
- The developed ESI-MS diffusion-based method is a viable technique for studying noncovalent interactions in solution.
- This approach is independent of the stability of interactions in the gas phase, overcoming a key limitation of conventional ESI-MS methods.
- The study provides insights into the stability of heme-myoglobin interactions under varying solution conditions.