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Thermal dissociation of streptavidin homotetramer in the gas phase: Subunit loss versus backbone fragmentation

  • Author(s) / Creator(s)
  • The results of time-resolved blackbody infrared radiative dissociation experiments performed on gaseous protonated ions, at charge states +15, +16 and +17, of the homotetramer streptavidin (S4) are reported. Evidence is found for three dissociation pathways involving (i) the loss of a single subunit, (ii) covalent cleavage of the backbone of one of the subunits and ejection of the resultant b212+ ion (followed by loss of complementary y106 ions), and (iii) the direct loss of one or more water molecules. The contribution of the different dissociation channels was found to be dependent on temperature, with the loss of subunit dominating at higher reaction temperatures and backbone fragmentation dominating at lower temperatures, and reaction times, with longer times favoring covalent fragmentation. Analysis of the dissociation kinetics and the influence of reaction time on the relative abundance of product ions indicate that backbone fragmentation and subunit loss are not produced via parallel pathways from a single reactant. Instead, the results suggest the presence of multiple, non-interconverting structures, which contribute differentially to the backbone fragmentation and subunit loss pathways. The results of molecular dynamics simulations performed on S416+ ions with different charge configurations suggest that unfolding of the N-terminus of the subunit may be associated with the backbone fragmentation pathway.

  • Date created
    2013
  • Subjects / Keywords
  • Type of Item
    Article (Published)
  • DOI
    https://doi.org/10.7939/R32F7K49S
  • License
    Attribution-NonCommerical-NoDerivs 4.0 International
  • Language
  • Citation for previous publication
    • Kitova, E. N., Sinelnikov, I., Deng, L., & Klassen, J. S. (2013). Thermal dissociation of streptavidin homotetramer in the gas phase: Subunit loss versus backbone fragmentation. International Journal of Mass Spectrometry, 345-347, 97-103. http://doi.org/10.1016/j.ijms.2012.08.025
  • Link to related item
    http://doi.org/10.1016/j.ijms.2012.08.025