Kinetics for tautomerizations and dissociations of triglycine radical cations

J Am Soc Mass Spectrom. 2009 Jun;20(6):996-1005. doi: 10.1016/j.jasms.2009.01.014. Epub 2009 Jan 29.


Fragmentations of tautomers of the alpha-centered radical triglycine radical cation, [GGG(*)](+), [GG(*)G](+), and [G(*)GG](+), are charge-driven, giving b-type ions; these are processes that are facilitated by a mobile proton, as in the fragmentation of protonated triglycine (Rodriquez, C. F. et al. J. Am. Chem. Soc. 2001, 123, 3006-3012). By contrast, radical centers are less mobile. Two mechanisms have been examined theoretically utilizing density functional theory and Rice-Ramsperger-Kassel-Marcus modeling: (1) a direct hydrogen-atom migration between two alpha-carbons, and (2) a two-step proton migration involving canonical [GGG](*+) as an intermediate. Predictions employing the latter mechanism are in good agreement with results of recent CID experiments (Chu, I. K. et al. J. Am. Chem. Soc. 2008, 130, 7862-7872).

Publication types

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

MeSH terms

  • Algorithms
  • Cations / chemistry
  • Hydrogen
  • Isomerism
  • Kinetics
  • Mass Spectrometry*
  • Models, Chemical*
  • Models, Molecular
  • Oligopeptides / chemistry*
  • Protons
  • Thermodynamics


  • Cations
  • Oligopeptides
  • Protons
  • Hydrogen
  • glycyl-glycyl-glycine