Formation of molecular radical cations of enkephalin derivatives via collision-induced dissociation of electrospray-generated copper (II) complex ions of amines and peptides

  • Ivan K. Chu
  • Christopher F. Rodriguez
  • Alan C. Hopkinson
  • K. W. Michael Siu
  • Tai-Chu Lau
Article

DOI: 10.1016/S1044-0305(01)00297-5

Cite this article as:
Chu, I.K., Rodriguez, C.F., Hopkinson, A.C. et al. J Am Soc Spectrom (2001) 12: 1114. doi:10.1016/S1044-0305(01)00297-5

Abstract

Fragmentation of some electrospray-generated complex ions, [63CuII(amine)M].2+, where M is an enkephalin derivative, produces the radical cation of the peptide, M.+. This ion has only been observed when M contains a tyrosyl or tryptophanyl residue plus a basic residue, typically arginyl or lysyl. A typical viable amine is diethylenetriamine. Collision-induced dissociation (CID) of the M.+ ion yields a prominent [M − 106].+ product ion for tyrosine-containing peptides, and a prominent [M − 129].+ ion for a tryptophan-containing peptide. These fragment ions are formed as a result of elimination of the tyrosyl and tryptophanyl side chains. Dissociation of these ions, in turn, produces second generation product ions, many of which are typically absent in the fragmentation of protonated peptide ions. Structures for some of these unusual ions are proposed.

Copyright information

© American Society for Mass Spectrometry 2001

Authors and Affiliations

  • Ivan K. Chu
    • 1
    • 3
  • Christopher F. Rodriguez
    • 1
  • Alan C. Hopkinson
    • 1
  • K. W. Michael Siu
    • 1
  • Tai-Chu Lau
    • 2
  1. 1.Department of Chemistry and Centre for Research in Mass SpectrometryYork UniversityTorontoCanada
  2. 2.Department of Biology and ChemistryCity University of Hong KongKowloonHong Kong
  3. 3.MDS SCIEXConcordCanada