MS2Assign, automated assignment and nomenclature of tandem mass spectra of chemically crosslinked peptides

J Am Soc Mass Spectrom. 2003 Aug;14(8):834-50. doi: 10.1016/S1044-0305(03)00327-1.


In a previous report (Young et al., Proc. Natl. Acad. Sci. U.S.A. 2000, 97, 5802-5806), we provided a proof-of-principle for fold recognition of proteins using a homobifunctional amine-specific chemical crosslinking reagent in combination with mass spectrometry analysis and homology modeling. In this current work, we propose a systematic nomenclature to describe the types of peptides that are generated after proteolysis of crosslinked proteins, their fragmentation by tandem mass spectrometry, and an automated algorithm for MS/MS spectral assignment called "MS2Assign." Several examples are provided from crosslinked peptides and proteins including HIV-integrase, cytochrome c, ribonuclease A, myoglobin, cytidine 5-monophosphate N-acetylneuraminic acid synthetase, and the peptide thymopentin. Tandem mass spectra were obtained from various crosslinked peptides using post source decay MALDI-TOF and collision induced dissociation on a quadrupole-TOF instrument, along with their automated interpretation using MS2Assign. A variety of possible outcomes are described and categorized according to the number of modified lysines and/or peptide chains involved, as well as the presence of singly modified (dead-end) lysine residues. In addition, the proteolysis and chromatographic conditions necessary for optimized crosslinked peptide recovery are presented.

Publication types

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

MeSH terms

  • Algorithms
  • Amino Acid Sequence
  • Animals
  • Cattle
  • Cross-Linking Reagents / chemistry*
  • Molecular Sequence Data
  • Peptides / chemistry*
  • Peptides / classification
  • Software*
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / methods*
  • Terminology as Topic*


  • Cross-Linking Reagents
  • Peptides