Sequential Digestion with Trypsin and Elastase in Cross-Linking Mass Spectrometry

Area of Science:

• Biochemistry
• Proteomics
• Structural Biology

Background:

• Cross-linking mass spectrometry (XL-MS) is vital for analyzing protein structure and interactions.
• Certain protein regions are difficult to analyze with XL-MS due to limited cleavage sites.

Purpose of the Study:

• To develop a novel strategy to overcome limitations in XL-MS for analyzing challenging protein regions.
• To enhance the identification of cross-linked residues in previously inaccessible areas.

Main Methods:

• A sequential digestion strategy employing trypsin and elastase was developed.
• Elastase was utilized to target larger tryptic peptides, exploiting its substrate-recognition properties.
• The protocol was applied to the TAF4-12 complex.

Main Results:

• The sequential digestion strategy successfully penetrated regions with low trypsin-cleavage site density.
• Previously inaccessible cross-linked residues were identified within the TAF4-12 complex.
• This method expands the scope of XL-MS analysis.

Conclusions:

• The trypsin-elastase sequential digestion is an effective method for enhancing XL-MS.
• This approach provides valuable insights into protein structures and interactions in previously uncharted regions.
• The strategy offers a significant advancement for protein modeling and interaction studies.