In the evolving field Cross-linkedPeptides. Inter-link α-β. MS/MS, non-cleavable cross-linkers (e.g. DSS). MS/MS, MS-cleavable cross-linkers (e.g.DSSO). MSn, MS-cleavable cross Read more of proteomics, the ability to map the architecture of complex biological systems relies heavily on advanced chemical tools. One of the most effective reagents I have encountered for studying protein-protein interactions is Disuccinimidyl sulfoxide, commonly referred to as DSSO. This rea Graph showing number of BSA crosslinked peptidesidentified using different noncleavable (BS3, DSS) and cleavable (DSSO) crosslinkers for various MSn methods.Read more gent has become a cornerstone in cross-linking mass spectrometry (XL-MS) due to its unique chemical properties and its ability to provide high-resolution data on how peptides orient themselves within a complex.
The Chemistry of DSSO
From my experience working with various labeling reagents, DSSO stands out because it contains two symmetric collision-induced dissociation (CID)-cleavable sites. This structural feature is critical for researchers. Unlike non-cleavable agents like DSS or BS3, which can complicate spectral interpretation, the sulfoxide-based linker in DSSO can be intentionally broken in the gas phase during tandem mass spectrometry (MS/MS).
DSSO has reactivity similar to that of DSS and BS3, primarily targeting lysine residues. This makes it a relia These results demonstrate that preferred fragmentation of the CS bonds inDSSO-interlinkedpeptidesof cytochrome c occurs as expected and is inde-pendent of Read more ble choice for stabilizing protein structures before analysis. When I evaluate the efficacy of these tools, I look for the ability to generate DSSO XL-MS protein interaction maps that accurately reflect the native state of the molecules. Furthermore, it provides complementary data to thiol-reactive and acidic residue-targeting reagents, all An MS3 method was developed specifically for the analysis ofDSSOcross-linkedpeptides. Full MS scans were performed at 60,000-m/z resolution in the Read more owing for a broader coverage of the interactome.
Optimizing the Workflow
Achieving high-quality data requires precise control over by L Foster—At a 10% BSA spike (w:w),.DSSOsamples showed a significant loss in the number of crosslinkedpeptideidentifications. In contrast, the 10% BSA spike Read more the experimental conditions. The interaction between the cross-linker and the target lysine residues is sensitive to buffer conditions and the concentration of the reagent.
When reviewing the technical literature, a graph showing the number of BSA crosslinked peptides often serves as a benchmark for comparing different cross-linkers. Using peptides labeled with DSSO, I have noted that the "doublet" signature peaks—a result of the cleavable nature of the reagent—are invaluable for distinguishing cross-linked species from background noise. This specificity is Aug 17, 2018—DSSO XL-MS protein interaction maps. We reasoned that the DSSO reaction with lysine residues reduces the accessibility of cross-linked peptides Read more what makes the DSSO approach so robust for structural biology.
Addressing the Complexity of Peptides
T by R Beveridge·2020·Cited by 84—For theDSSO-crosslinkedpeptides linkedpeptideidentification by fragment intensity prediction to study proteininteractionsand structures.Read more he analysis of peptides derived from cross-linked proteins involves sophisticated mass spectrometry methods, such as MSn or stepped-HCD. Because the DSSO linker is specifically designed to fragment, it allows for the concurrent release of cross-linked peptide constituents. This simplifies the sequencing process, as the mass spectrometer can identify the individual components of the cross-link rather than trying to resolve a massive, intact structure.
Whether investigating histone landscapes or membrane-permeable structures, the fundamental interaction being captured is a snapshot of the protein's spatial configuration. By utilizing DSSO, I can ensure that the structural data obtained is representative of the true biological interaction state.
Summary of Findings
* Reactivity: Comparable to DSS/BS3 with the added advantage of MS-cleavability.
* Data Integrity: The doublet signature provided by DSSO facilitates high-confidence identification, reducing false positives in complex mixtures.
* Versatility: Useful for both in vitro and in cellulo studies, providing a comprehensive view of protein interactions.
By integrating these specialized reagents into a structured analysis pipeline, it is possible to gain a clearer picture of how various peptides associate and function. The ongoing development of these tools continues to push the boundaries of what we can visualize in structural proteomics, proving that the choice of cross-linker is just as vital as the mass spectrometry method itself.