Internal energy distribution in charge inversion mass spectrometry using alkali metal targets

2017

Mass Spectrometry

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High energy collision processes for singly charged positive ions using an alkali metal target are con rmed, as a charge inversion mass spectrometry, to occur by electron transfers in successive collisions and the dissociation processes involve the formation of energy-selected neutral species from near-resonant neutralization with alkali metal targets. A doubly charged thermometer molecule was made to collide with alkali metal targets to give singly and doubly charged positive ions. e internal energy resulting from the electron transfer with the alkali metal target was very narrow and centered at a particular energy. is narrow internal energy distribution can be attributed to electron transfer by Landau-Zener potential crossing between the precursor ion and an alkali metal atom, and the coulombic repulsion between singly charged ions in the exit channel. A large cross section of more than 10 −14 cm 2 was estimated for high-energy electron transfer dissociation (HE-ETD). Doubly protonated phosphorylated peptides obtained by electrospray ionization were collided with Xe and Cs targets to give singly and doubly charged positive ions. Whereas doubly charged fragment ions resulting from CAD were dominant in the case of the Xe target, singly charged fragment ions resulting from ETD were dominant with the Cs target. HE-ETD using the Cs target provided all of the z-type ions by N-C α bond cleavage without the loss of the phosphate groups. e results demonstrate that HE-ETD with an alkali metal target allowed the position of phosphorylation and the amino acid sequence of peptides with post translational modi cations (PTM) to be determined.

Section: Introductionmentioning

confidence: 99%

“…11,12) e internal energy distribution of HE-ETD measured using a thermometer molecule is discussed. e usefulness of HE-ETD using an alkali metal target for the sequencing of peptides with PTM is discussed.…”

Section: Introductionmentioning

confidence: 99%

Study of Ion Dynamics by Electron Transfer Dissociation: Alkali Metals as Targets

2017

Mass Spectrometry

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“…Charge inversion mass spectrometry using alkali metal targets [23][24][25][26][27][28][29] for singly protonated peptides and amino acids provided the information of the radical traps in the dissociation mechanism of the charge reduced peptides [28,30,31]. N-C␣ bond cleavages induced by electron-transfer processes of multiply charged peptides upon collision with alkali metals have been reported by Hvelplund and coworkers [32][33][34][35][36][37].…”

mentioning

confidence: 96%

“…The charge reduced peptide cation radicals formed by ECD and ETD are known to dissociate at various positions via the low-energy transitionstate for bond cleavage [16 -20]. Differences between ECD and ETD are also reported [15,21,22] .Charge inversion mass spectrometry using alkali metal targets [23][24][25][26][27][28][29] for singly protonated peptides and amino acids provided the information of the radical traps in the dissociation mechanism of the charge …”

mentioning

confidence: 99%

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High-energy electron transfer dissociation (HE-ETD) using alkali metal targets for sequence analysis of post-translational peptides

J. Am. Soc. Mass Spectrom.

Matsumoto

Hashimoto

et al. 2010

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Post-translational modifications (PTMs) of proteins are important in the activation, localization, and regulation of protein function in vivo. The usefulness of electron capture dissociation (ECD) and electron-transfer dissociation (ETD) in tandem mass spectrometry (MS/MS) using low-energy (LE) trap type mass spectrometer is associated with no loss of a labile PTM group regarding peptide and protein sequencing. The experimental results of high-energy (HE) collision induced dissociation (CID) using the Xe and Cs targets and LE-ETD were compared for doubly-phosphorylated peptides TGFLT(p)EY(p)VATR (1). Although HE-CID using the Xe target did not provide information on the amino acid sequence, HE-CID using the Cs target provided all the z-type ions without loss of the phosphate groups as a result of HE-ETD process, while LE-ETD using fluoranthene anion gave only z-type ions from z 5 to z 11 . The difference in the results of HE-CID between the Xe and Cs targets demonstrated that HE-ETD process with the Cs target took place much more dominantly than collisional activation. The difference between HE-ETD using Cs targets and LE-ETD using the anion demonstrated that mass discrimination was much weaker in the high-energy process. HE-ETD was also applied to three other phosphopeptides YGGMHRQEX(p)VDC (2: X ϭ S, 3: X ϭ T, 4: X ϭ Y). The HE-CID spectra of the doubly-protonated phosphopeptides () of 2, 3, and 4 using the Cs target showed a very similar feature that the c-type ions from c 7 to c 11 and the z-type ions from z 7 to z 11 were formed via N-C␣ bond cleavage without a loss of the phosphate group. (J Am Soc Mass Spectrom 2010, 21, 1482-1489) © 2010 American Society for Mass Spectrometry P ost-translational modifications (PTMs) of proteins are important in vivo, especially, reversible protein phosphorylation, principally localized on serine, threonine, or tyrosine residues, is one of the most important and well-studied. Phosphorylations play crucial roles in the regulation of cellular processes such as cell cycle, cell growth, apoptosis, and signal transduction [1,2]. Although the mass analysis of phosphorylated proteins and peptides has become possible since the development of electrospray ionization (ESI) technique [3], the determination of phosphorylated positions has not yet been achieved by the most popular dissociation method, namely, a low-energy collisionally activated dissociation (LE-CAD) performed by using the tandem mass spectrometry (MS/ MS) [4]. Electron capture dissociation (ECD) using a Fourier transform ion cyclotron resonant mass spectrometer (FT-ICR-MS) [5][6][7][8] and electron-transfer dissociation (ETD) using a linear trap mass spectrometer [9,10] can provide information on c-and z-type ions [11,12] produced via N-C␣ backbone cleavage with no loss of labile PTM groups, such as phosphate and sulfate groups [13,14]. The N-C␣ backbone cleavage is different from other fragmentations brought about by collisional activation or infrared photoexcitation of closedshell cations [15]. The charge reduced p...

Dissociation mechanisms of neutral methyl stearate and its hydrogen atom adduct formed from the respective positive ions by electron transfer

Kitaguchi

2006

J. Mass Spectrom.

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The mechanism of dissociation of neutral methyl stearate and its hydrogen atom adduct was investigated by charge inversion mass spectrometry using an alkali metal target. Migrations of functional groups in fatty acid ester ions are often observed during the dissociation of the cations in collisionally activated dissociation (CAD). In the charge inversion spectrum, the main dissociation channels of methyl stearate molecule are the loss of a CH3 radical or a H atom. To identify the source of the CH3 radical and the H atom, the charge inversion spectra of partially deuterated methyl stearate (C17H35COOCD3) were measured. The loss of CH3 occurred through elimination from the methoxy methyl group and that of H occurred through elimination from the hydrocarbon chain of the fatty acid group. In the protonated ester, a simultaneous loss of CH3 (from the methoxy methyl group) and a H atom or a H2 molecule was observed. The charge inversion process gave the dissociation fragments with almost no migration of atoms. Only a few peaks that were structure sensitive were observed in the higher mass region in the charge inversion spectra; these peaks were associated with dissociations of energy-selected neutral species, unlike the case of CAD spectra in which they result from dissociation of ions. Charge inversion mass spectrometry with alkali metal targets provided direct information on the dissociation mechanism of methyl stearate and its hydrogen atom adduct without any migration of functional groups.