Journal of the American Society for Mass Spectrometry

, Volume 17, Issue 7, pp 923–931

Ion Trap Collision-Induced Dissociation of Human Hemoglobin α-Chain Cations


  • Tegafaw T. Mekecha
    • Department of Chemistry, 1393 Brown LaboratoriesPurdue University
  • Ravi Amunugama
    • Department of Chemistry, 1393 Brown LaboratoriesPurdue University
    • Department of Chemistry, 1393 Brown LaboratoriesPurdue University
Focus: Van Berkel, 2005 Biemann Medal Awardee

DOI: 10.1016/j.jasms.2006.01.004

Cite this article as:
Mekecha, T.T., Amunugama, R. & McLuckey, S.A. J Am Soc Mass Spectrom (2006) 17: 923. doi:10.1016/j.jasms.2006.01.004


Multiply protonated human hemoglobin α-chain species, ranging from [M+4H]4+ to [M + 20H]20+, have been subjected to ion trap collisional activation. Cleavages at 88 of the 140 peptide bonds were indicated, summed over all charge states, although most product ion signals were concentrated in a significantly smaller number of channels. Consistent with previous whole protein ion dissociation studies conducted under similar conditions, the structural information inherent to a given precursor ion was highly sensitive to charge state. A strongly dominant cleavage at D75/M76, also noted previously in beam-type collisional activation studies, was observed for the [M+8H]8+ to [M+11H]11+ precursor ions. At lower charge states, C-terminal aspartic acid cleavages were also prominent but the most abundant products did not arise from the D75/M76 channel. The [M+12H]12+–[M+16H]16+ precursor ions generally yielded the greatest variety of amide bond cleavages. With the exception of the [M+4H]4+ ion, all charge states showed cleavage at the L113/P114 bond. This cleavage proved to be the most prominent dissociation for charge states [M+14H]14+ and higher. The diversity of dissociation channels observed within the charge state range studied potentially provides the opportunity to localize residues associated with variants via a top-down tandem mass spectrometry approach.

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© American Society for Mass Spectrometry 2006