Journal of the American Society for Mass Spectrometry

, Volume 18, Issue 11, pp 2007–2013

Abundant b-type ions produced in electron capture dissociation of peptides without basic amino acid residues

  • Haichuan Liu
  • Kristina Håkansson

DOI: 10.1016/j.jasms.2007.08.015

Cite this article as:
Liu, H. & Håkansson, K. J Am Soc Mass Spectrom (2007) 18: 2007. doi:10.1016/j.jasms.2007.08.015


We have investigated electron capture dissociation (ECD) of doubly protonated peptides with few or no basic amino acid residues (BAARs). For peptides containing one His, abundant b-type ions were only found when His was located adjacent to the N-terminus. Interestingly, b-type ions, particularly b5+, were found to be the dominant product ions in ECD of peptides without BAARs. Fragmentation patterns of luteinizing hormone releasing hormone (LHRH) and vasopressin (VP), containing one Arg and one His, respectively, were compared to those of Q8-LHRH and oxytocin (OT) in which the BAAR is replaced with a non-BAAR. More b-type ions were found for Q8-LHRH and OT than for LHRH and VP. We also performed ECD of melittin and found no b-type ions from ECD of the 4+ charge state; however, many low abundance b-type ions were produced in ECD of the 5+ charge state. Possible mechanisms for the formation of b-type ions are discussed and we propose that such ions are formed as a consequence of protons being located at backbone amide nitrogens.

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© American Society for Mass Spectrometry 2007

Authors and Affiliations

  • Haichuan Liu
    • 1
  • Kristina Håkansson
    • 1
  1. 1.Department of ChemistryUniversity of MichiganAnn ArborUSA
  2. 2.Biomolecular Resource Center Mass Spectrometry Facility and Department of Cell and Tissue BiologyUniversity of CaliforniaSan FranciscoUSA