Isotopically coded cleavable cross-linker for studying protein-protein interaction and protein complexes.

Area of Science:

• Biochemistry
• Analytical Chemistry
• Proteomics

Background:

• Studying protein-protein interactions is crucial for understanding cellular functions.
• Chemical cross-linking coupled with mass spectrometry (MS) is a key method for analyzing protein complexes.
• Existing methods face challenges in detecting cross-links and distinguishing between different types of cross-linked peptides.

Purpose of the Study:

• To develop a novel, isotopically coded, and cleavable cross-linker for enhanced protein complex analysis.
• To improve the accuracy and ease of identifying protein-protein interactions and cross-linking events.
• To create a software algorithm for automated detection and classification of cross-links.

Main Methods:

• Synthesis of an isotopically coded ethylene glycol bis(succinimidylsuccinate) derivative (D12-EGS).
• Application of D12-EGS in a 1:1 mixture with its non-isotopic counterpart (H12).
• Hydrolytic cleavage of cross-linked peptides followed by MS sequencing and analysis using a custom software algorithm.

Main Results:

• The D12-EGS cross-linker facilitates easy detection of cross-links due to isotopic coding.
• Hydrolytic cleavage allows for rapid differentiation between dead-end, intrapeptide, and interpeptide cross-links based on distinct mass shifts.
• The developed software algorithm enables automatic screening and identification of cross-links and their types in mass spectra.

Conclusions:

• The combination of the cleavable, isotopically coded cross-linker and the software algorithm provides a powerful and robust tool for studying multi-component protein complexes.
• This approach overcomes limitations in detecting and identifying cross-links in complex biological samples.
• The method enhances the efficiency and accuracy of protein-protein interaction studies in proteomics.