Research Article

Journal of The American Society for Mass Spectrometry

, Volume 23, Issue 3, pp 483-488

Tryptic y ++ Fragment Ion Distributions Are Guided by Coulombic Repulsion

  • Karl K. IrikuraAffiliated withChemical and Biochemical Reference Data Division, National Institute of Standards and Technology Email author 
  • , John K. MerleAffiliated withDepartment of Chemistry, Winston-Salem State University
  • , Yamil Simón-MansoAffiliated withChemical and Biochemical Reference Data Division, National Institute of Standards and Technology

Abstract

Ideal tryptic peptides contain only a single basic residue, located at the C-terminus. Collisional fragmentation of their doubly- or triply-protonated ions generates doubly-charged y ++ fragment ions with modest intensities. The size distribution of the y ++ fragments, when averaged over many spectra, corresponds closely to the expectations from charge-directed backbone cleavage and a Coulomb-Boltzmann distribution of mobile protons. This observation should be helpful in developing mechanistic models for y ++ formation.

Key words

Collision-induced dissociation CID Electrostatics Fragmentation Mobile proton model Peptide ion Proteomics Quantum chemistry Tandem mass spectrometry