Dissociation of heme from gaseous myoglobin ions studied by infrared multiphoton dissociation spectroscopy and Fourier-transform ion cyclotron resonance mass spectrometry

Yi Sheng Wang, Sahadevan Sabu, Shih Chia Wei, C. M. Josh Kao, Xianglei Kong, Shing Chih Liau, Chau Chung Han, Huan Cheng Chang, Shih Yu Tu, A. H. Kung, John Z.H. Zhang

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Abstract

Detachment of heme prosthetic groups from gaseous myoglobin ions has been studied by collision-induced dissociation and infrared multiphoton dissociation in combination with Fourier-transform ion cyclotron resonance mass spectrometry. Multiply charged holomyoglobin ions (hMbn+) were generated by electrospray ionization and transferred to an ion cyclotron resonance cell, where the ions of interest were isolated and fragmented by either collision with Ar atoms or irradiation with 3 μm photons, producing apomyoglobin ions (aMbn+). Both charged heme loss (with [Fe (III) -heme]+ and aMb (n-1) + as the products) and neutral heme loss (with [Fe(II)-heme] and aMbn+ as the products) were detected concurrently for hMbn+ produced from a myoglobin solution pretreated with reducing reagents. By reference to Ea =0.9 eV determined by blackbody infrared radiative dissociation for charged heme loss of ferric hMbn+, an activation energy of 1.1 eV was deduced for neutral heme loss of ferrous hMbn+ with n=9 and 10.

Original languageEnglish (US)
Article number133310
JournalJournal of Chemical Physics
Volume125
Issue number13
DOIs
StatePublished - Oct 12 2006

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ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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