Exploring Spacer Arm Structures for Designs of Asymmetric Sulfoxide-Containing MS-Cleavable Cross-Linkers

Anal Chem. 2020 Apr 21;92(8):6026-6033. doi: 10.1021/acs.analchem.0c00298. Epub 2020 Mar 31.

Abstract

Cross-linking mass spectrometry (XL-MS) has become a powerful structural tool for defining protein-protein interactions (PPIs) and elucidating architectures of large protein assemblies. To advance XL-MS studies, we have previously developed a series of sulfoxide-containing MS-cleavable cross-linkers to facilitate the detection and identification of cross-linked peptides using multistage mass spectrometry (MSn). While current sulfoxide-based cross-linkers are effective for in vivo and in vitro XL-MS studies at the systems-level, new reagents are still needed to help expand PPI coverage. To this end, we have designed and synthesized six variable-length derivatives of disuccinimidyl sulfoxide (DSSO) to better understand the effects of spacer arm modulation on MS-cleavability, fragmentation characteristics, and MS identification of cross-linked peptides. In addition, the impact on cross-linking reactivity was evaluated. Moreover, alternative MS2-based workflows were explored to determine their feasibility for analyzing new sulfoxide-containing cross-linked products. Based on the results of synthetic peptides and a model protein, we have further demonstrated the robustness and predictability of sulfoxide chemistry in designing MS-cleavable cross-linkers. Importantly, we have identified a unique asymmetric design that exhibits preferential fragmentation of cross-links over peptide backbones, a desired feature for MSn analysis. This work has established a solid foundation for further development of sulfoxide-containing MS-cleavable cross-linkers with new functionalities.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Cross-Linking Reagents / chemical synthesis*
  • Cross-Linking Reagents / chemistry
  • Mass Spectrometry
  • Molecular Structure
  • Safrole / analogs & derivatives*
  • Safrole / chemistry

Substances

  • Cross-Linking Reagents
  • Safrole
  • sulfoxide