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Evaluation of Protein–Protein Interactions using an On-Membrane Digestion Technique
Published on: July 19, 2019
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Improved protease digestion conditions for membrane protein detection
Lie Min1, Leila H Choe1, Kelvin H Lee1
1Department of Chemical and Biomolecular Engineering and Delaware Biotechnology Institute, University of Delaware, Newark, DE, USA.
Electrophoresis
|April 18, 2015
Summary
Improved protease digestion methods enhance membrane protein identification. Optimized conditions using SDS or methanol/RapiGest significantly increase sequence coverage for proteins like bacteriorhodopsin and Selenoprotein S.
Area of Science:
- Proteomics
- Biochemistry
- Membrane Protein Analysis
Background:
- Membrane proteins are crucial but challenging to study due to their hydrophobic nature.
- Existing protease digestion methods often yield low sequence coverage for membrane proteins.
- Bacteriorhodopsin (BR) serves as a model for investigating membrane protein digestion.
Purpose of the Study:
- To develop and optimize protease digestion conditions for improved membrane protein detection and sequence coverage.
- To evaluate the efficacy of new digestion protocols on model membrane proteins and complex proteomes.
Main Methods:
- Investigated enzymatic digestion of bacteriorhodopsin using trypsin and chymotrypsin.
- Tested varying concentrations of RapiGest, methanol (MeOH), and SDS.
- Applied optimized conditions (0.01% SDS or 10% MeOH/0.01% RapiGest) to Selenoprotein S and Escherichia coli membrane protein fractions.
Main Results:
- Initial in-gel digestion of BR yielded 17% sequence coverage.
- Optimized conditions achieved over 40% BR sequence coverage with trypsin, a significant improvement.
- Enhanced sequence coverage, including transmembrane domain peptides, was observed for Selenoprotein S.
- Identified 140-148 membrane proteins from Escherichia coli using the improved methods.
Conclusions:
- The developed protease digestion conditions substantially improve membrane protein sequence coverage.
- These optimized methods are effective for analyzing diverse membrane proteins and complex biological samples.
- The findings facilitate more comprehensive proteomic studies of membrane proteins.
