Identification of cross-linked peptides by high-resolution precursor ion scan

Anal Chem. 2010 Feb 1;82(3):909-16. doi: 10.1021/ac902051q.

Abstract

Chemical cross-linking coupled to mass spectrometry analysis has become a realistic alternative to the study of proteins structure and interactions, especially when these systems are not amenable to high-resolution techniques such as protein crystallography or nuclear magnetic resonance. One of the main bottlenecks of this approach relies on the detection of cross-linked peptides, as they are usually present in substoichiometric amounts in complex samples. It was shown that one of the main fragmentation pathways of disuccinimidyl suberate (DSS) cross-linked peptides yields diagnostic ions, whose structure is composed of a rearranged lysine side chain and the spacer arm of the linker. In this report, we demonstrate the feasibility of detecting these modified peptides based on a precursor ion scan in a quadrupole time-of-flight (Q-TOF) instrument. It was shown that the fragmentation of nonmodified tryptic peptides hardly generates ions with the same nominal mass of the diagnostic ions, making the precursor ion scan very specific to N-hydroxysuccinimide (NHS)-based cross-linkers. Moreover, the experimental setup is the same as in the case of a regular cross-linking experiment, not demanding any additional experimental steps that would increase sample handling. The results obtained with protein samples allowed us to propose an algorithm that could be implemented in a software to process data from cross-linking experiments in an automated and high-throughput way.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Chromatography, High Pressure Liquid / methods*
  • Cross-Linking Reagents / chemistry*
  • Molecular Sequence Data
  • Peptides / analysis*
  • Peptides / chemistry
  • Protein Structure, Tertiary
  • Succinimides / chemistry
  • Tandem Mass Spectrometry / methods*

Substances

  • Cross-Linking Reagents
  • Peptides
  • Succinimides
  • N-hydroxysuccinimide
  • disuccinimidyl suberate