Journal of the American Society for Mass Spectrometry

, Volume 1, Issue 6, pp 473–480

Investigations of gas-phase lithium-peptide adducts: Tandem. mass spectrometry and semiempirical studies


  • Julie A. Leary
    • College of ChemistryUniversity of California
  • Zhongrui Zhou
    • College of ChemistryUniversity of California
  • Sherri A. Ogden
    • College of ChemistryUniversity of California
  • Todd D. Williams
    • College of ChemistryUniversity of California

DOI: 10.1016/1044-0305(90)85030-P

Cite this article as:
Leary, J.A., Zhou, Z., Ogden, S.A. et al. J Am Soc Mass Spectrom (1990) 1: 473. doi:10.1016/1044-0305(90)85030-P


Tandem mass spectrometry using a hybrid mass spectrometer of BEqQ geometry was used to investigate the gas-phase formation of the [An+ Li − H)+ ion from lithium-peptide adducts. High resolution mass measurements as well as precursor and product ion scans of five peptides indicate that one source of [An+ Li − H) arises from [An+ Li]+. Semiempirical calculations (MNOO) and metastable ion decomposition studies of the peptide Gly-Gly-Gly show that the lithium ion prefers to coordinate to the three internal carbonyls of the neutral molecule to give a species that is energetically more stable than the lithiated zwitterion by 305 kJ/mol. Theoretical and experimental evidence suggest that the monolithiated precursor ion population may be a distribution of structural isomers. (J Am Soc Mass Spectrom 1990, 1, 473-480)

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© American Society for Mass Spectrometry 1990