Wang Yi-Sheng, Sabu Sahadevan, Wei Shih-Chia, Josh Kao C-M, Kong Xianglei, Liau Shing-Chih, Han Chau-Chung, Chang Huan-Cheng, Tu Shih-Yu, Kung A H, Zhang John Z H
Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan.
J Chem Phys. 2006 Oct 7;125(13):133310. doi: 10.1063/1.2221696.
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 mum 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.
通过碰撞诱导解离和红外多光子解离并结合傅里叶变换离子回旋共振质谱，研究了气态肌红蛋白离子中血红素辅基的脱离。通过电喷雾电离产生多电荷全肌红蛋白离子（hMbn+），并将其转移到离子回旋共振池中，在那里，通过与氩原子碰撞或用3μm光子辐照，将感兴趣的离子分离并碎片化，产生脱辅基肌红蛋白离子（aMbn+）。对于用还原试剂预处理的肌红蛋白溶液产生的hMbn+，同时检测到带电荷的血红素损失（产物为[Fe(III)-血红素]+和aMb(n-1)+）和中性血红素损失（产物为[Fe(II)-血红素]和aMbn+）。参照通过黑体红外辐射解离确定的铁离子hMbn+带电荷血红素损失的Ea = 0.9 eV，推导得出n = 9和10时亚铁离子hMbn+中性血红素损失的活化能为1.1 eV。
