Mass spectrometry of full-length integral membrane proteins to define functionally relevant structural features

Area of Science:

• Structural Biology
• Biochemistry
• Analytical Chemistry

Background:

• Integral membrane protein structure determination is challenging, with fewer structures solved compared to soluble proteins.
• Mass spectrometry offers valuable insights into membrane protein states throughout structure determination.
• Standard MALDI methods face challenges with integral membrane proteins.

Purpose of the Study:

• To present an optimized MALDI method for integral membrane protein analysis.
• To provide detailed protocols for sample preparation, deposition, and domain determination.
• To demonstrate the utility of MALDI-MS in protein structure determination workflows.

Main Methods:

• Development and optimization of a Matrix-Assisted Laser Desorption/Ionization (MALDI) method for membrane proteins.
• Application of limited proteolysis for domain determination.
• Utilizing MALDI-time of flight mass spectrometry for protein characterization.

Main Results:

• The optimized MALDI method facilitates integral membrane protein analysis.
• Detailed sample preparation and deposition protocols are provided.
• MALDI-MS aids in identifying initiation sites, tailoring proteins, and evaluating selenomethionine replacement.

Conclusions:

• Optimized MALDI-MS is a powerful tool for integral membrane protein structure determination.
• This technique provides critical information from protein expression to model building.
• The approach is exemplified by applications in ion channel structural biology.