A novel multifunctional labeling reagent for enhanced protein characterization with mass spectrometry

Rapid Commun Mass Spectrom. 2001;15(24):2387-92. doi: 10.1002/rcm.517.


Individual peptides with lysine at the C-terminus as well as protein tryptic digests were reacted with 2-methoxy-4,5-dihydro-1H-imidazole, converting lysine residues to their 4,5-dihydro-1H-imidazol-2-yl derivatives. The mass spectra of derivatized digests exhibit a greater number of more intense features than their underivatized counterparts, thus increasing the information obtained in peptide mapping experiments. Additionally, MS/MS spectra of the derivatized peptides are greatly simplified in comparison to their native species, yielding primarily an easily interpretable series of y-ions. Finally, this novel label also enables differential quantitation studies, as a stable isotopic form containing four deuterium atoms can readily be produced.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Calibration
  • Horses
  • Hydrolysis
  • Imidazoles / chemistry
  • Indicators and Reagents
  • Lysine / analysis
  • Molecular Sequence Data
  • Myoglobin / analysis
  • Peptide Fragments / analysis
  • Proteins / chemistry*
  • Proteome / analysis
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
  • Spectroscopy, Fourier Transform Infrared
  • Trypsin


  • 2-methoxy-4,5-dihydro-1H-imidazole
  • Imidazoles
  • Indicators and Reagents
  • Myoglobin
  • Peptide Fragments
  • Proteins
  • Proteome
  • Trypsin
  • Lysine