Efficient protein conformation dynamics characterization enabled by mobility-mass spectrometry

Area of Science:

• Biochemistry
• Analytical Chemistry
• Structural Biology

Background:

• Protein structure dynamics in solution and gas phase are challenging to study.
• Ion mobility mass spectrometry (IM-MS) measures gas-phase protein collision cross-sections (CCS).
• Conventional methods limit capturing protein dynamics under varying solvent conditions.

Purpose of the Study:

• Develop an efficient protocol to characterize protein conformation dynamics.
• Investigate factors affecting protein structures: pH, temperature, ionization, and disulfide bonds.
• Understand protein structural changes from solution to gas phase.

Main Methods:

• Combined mobility capillary electrophoresis (MCE) and ion mobility mass spectrometry (IM-MS).
• Evaluated key factors influencing protein conformations.
• Monitored protein conformation dynamics and compared results across different proteins.

Main Results:

• pH decrease from 7.0 to 3.0 primarily drives unfolding in proteins without disulfide bonds.
• Harsh ionization processes dominate unfolding in proteins with disulfide bonds.
• Disulfide bonds preserve conformations in acidic solutions, dependent on their position, but not during ionization.

Conclusions:

• The MCE-IM-MS protocol efficiently characterizes protein conformation dynamics.
• pH and disulfide bonds play distinct roles in protein structural stability.
• Disulfide bond position is critical for conformational preservation in acidic environments.