title: Dissociation of trivalent metal ion (Al(3+), Ga(3+), In(3+) and Rh(3+))--peptide complexes under electron capture dissociation conditions.
abstract: BACKGROUND
  The electron capture dissociation (ECD) of proteins/peptides is affected by the nature of charge carrier. It has been reported that transition metal ions could tune the ECD pathway of peptides. To further explore the charge carrier effect of metal ions, ECD of peptides adducted with trivalent transition metal ions, including group IIIB (Al(3+), Ga(3+), and In(3+) ) and Rh(3+), were investigated and compared with that of the lanthanide ion (Ln(3+)).
  
  
  METHODS
  Bradykinin-derived peptides were used as model peptides to probe the dissociation pathways. The ECD experiments were performed on a Bruker APEX III 4.7T Fourier transform ion cyclotron resonance (FTICR) mass spectrometer.
  
  
  RESULTS
  Typical c-/z-ions with and without metal ions were observed in the ECD of peptides adducted with Group IIIB metal ions as charge carriers. Connection of non-metalated c-ions and metalated z-ions at the position of the serine residue indicated that serine is one of the binding sites of the metal ion on the model peptides. Typical slow heating ions, including metalated a-/b-ions and non-metalated y-ions, were generated in ECD of Rh(3+) -adducted peptides.
  
  
  CONCLUSIONS
  Based on the experimental results, it is proposed that (i) for Group IIIB metal ion-peptide complexes, the incoming electron is captured by the proton in the salt-bridge structures of precursor ions; (ii) for Rh(3+) -peptide complexes, the incoming electron is captured by the metal ion due to the formation of charge-solvated precursor ions formed through arginine residue-metal coordination. Our results indicate that the heterogeneity of precursor ions plays an important role for the ECD of metalated peptides.
authors: Department of Chemistry, The Chinese University of Hong Kong, Hong Kong SAR.|Shandong Academy of Sciences, Jinan, Shandong, P. R. China.
authors: Xiangfeng
authors: X
authors: Chen
authors: Department of Chemistry, The Chinese University of Hong Kong, Hong Kong SAR.
authors: Guoqiang
authors: G
authors: Liu
authors: Department of Chemistry, The Chinese University of Hong Kong, Hong Kong SAR.
authors: Y L
authors: YL
authors: Elaine Wong
authors: Department of Chemistry, The Chinese University of Hong Kong, Hong Kong SAR.|Biological Sciences Division and Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Washington, USA.
authors: Liulin
authors: L
authors: Deng
authors: Department of Chemistry, The Chinese University of Hong Kong, Hong Kong SAR.
authors: Ze
authors: Z
authors: Wang
authors: Department of Chemistry, The Chinese University of Hong Kong, Hong Kong SAR.
authors: Wan
authors: W
authors: Li
authors: Department of Chemistry, The Chinese University of Hong Kong, Hong Kong SAR.
authors: T-W
authors: TW
authors: Dominic Chan
mesh_terms: D001920:Bradykinin / Q000737:chemistry; D004583:Electrons; D013058:Mass Spectrometry / Q000379:methods*; D008670:Metals / Q000737:chemistry*; D010455:Peptides / Q000737:chemistry*; D012694:Serine / Q000737:chemistry
chemical_list: D008670:Metals; D010455:Peptides; D012694:Serine; D001920:Bradykinin