Full Membrane Protein Coverage Digestion and Quantitative Bottom-Up Mass Spectrometry Proteomics

Area of Science:

• Proteomics
• Analytical Chemistry
• Biochemistry

Background:

• Integral membrane proteins constitute a significant portion of the proteome (approximately one-third).
• Efficient solubilization and digestion of these proteins are essential for comprehensive bottom-up proteomic analysis.
• Existing methods often face challenges in fully solubilizing integral membrane proteins.

Purpose of the Study:

• To develop and validate a robust protocol for the efficient digestion of integral membrane proteins.
• To improve the accuracy and completeness of bottom-up proteomic measurements.
• To enable quantitative analysis of membrane proteins using stable-isotope labeling.

Main Methods:

• Solubilization of integral membrane proteins using sodium deoxycholate and lauryl sarcosine with heat treatment (95 °C).
• Purification of a peptide subset via reverse-phase solid-phase extraction.
• Fractionation using strong-cation exchange chromatography.
• Analysis by nano-liquid chromatography coupled with data-dependent tandem mass spectrometry.
• Stable-isotope coding of peptides via dimethylation for three-way sample multiplexing in quantitative proteomics.

Main Results:

• Demonstration of efficient digestion of integral membrane proteins using the described protocol.
• Successful recovery and analysis of peptides derived from integral membrane proteins.
• Implementation of a quantitative proteomics strategy enabling three-way sample comparison.

Conclusions:

• The developed protocol significantly enhances the ability to perform comprehensive bottom-up proteomic analyses, including integral membrane proteins.
• This method provides a foundation for more accurate and complete proteomic profiling.
• The quantitative approach facilitates robust comparative studies of complex biological samples.