Solvent-induced structural transitions of lysozyme in an electrospray ionization source

Area of Science:

• Biochemistry
• Analytical Chemistry
• Physical Chemistry

Background:

• Electrospray ionization mass spectrometry (ESI-MS) is crucial for studying protein structural dynamics.
• Understanding the solution-to-gas phase structural correlation in ESI-MS is vital for accurate protein analysis.
• Hen egg white lysozyme (Lyz) is a model protein with a known compact solution structure.

Purpose of the Study:

• To characterize the structural changes of denatured lysozyme during its transfer into the gas phase via ESI.
• To elucidate the role of organic cosolvents and acids in modulating protein structure during ESI.
• To provide a detailed understanding of solvent environment influences on protein structure in ESI-MS.

Main Methods:

• Electrospray ionization mass spectrometry (ESI-MS) was employed for structural characterization.
• Hen egg white lysozyme (Lyz) was studied in solution with organic cosolvents and acids.
• Analysis focused on structural collapse and charge state reduction during ESI.

Main Results:

• Organic cosolvents induce the collapse of extended lysozyme structures into compact forms during ESI.
• Acids facilitate this compaction by reducing lysozyme's charge state and electrostatic repulsion.
• The structural transition primarily occurs within the charged droplets generated during ESI.

Conclusions:

• The solvent environment significantly influences protein structure during the ESI-MS gas-phase transfer.
• ESI-MS can reveal conformational changes induced by solution conditions.
• This study enhances the application of ESI-MS for detailed protein structural investigations.