Capturing Polyradical Protein Cations after an Electron Capture Event: Evidence for their Stable Distonic Structures in the Gas Phase

Baba, Takashi; Campbell, J. Larry

doi:10.1007/s13361-015-1207-x

Cited by 5 publications

(4 citation statements)

References 32 publications

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“…Multistep electron transfer to high charge states of proteins has been claimed to produce diradicals on the basis of their reaction with residual oxygen. 60 In contrast, the dissociations of doubly reduced heptanucleotide ions reported here indicated that no diradicals were formed.…”

Section: ■ Results and Discussioncontrasting

confidence: 54%

“…This may indicate that the transfer of the second electron in the 3 +• → 2 + reduction step resulted in the formation of a closed-shell dication and not a dication diradical. Multistep electron transfer to high charge states of proteins has been claimed to produce diradicals on the basis of their reaction with residual oxygen . In contrast, the dissociations of doubly reduced heptanucleotide ions reported here indicated that no diradicals were formed.…”

Section: Resultsmentioning

confidence: 52%

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Do d(GCGAAGC) Cations Retain the Hairpin Structure in the Gas Phase? A Cyclic Ion Mobility Mass Spectrometry and Density Functional Theory Computational Study

Wan,

Nytka,

Qian

et al. 2023

J. Am. Soc. Mass Spectrom.

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Section: ■ Results and Discussioncontrasting

confidence: 54%

Section: Resultsmentioning

confidence: 52%

Do d(GCGAAGC) Cations Retain the Hairpin Structure in the Gas Phase? A Cyclic Ion Mobility Mass Spectrometry and Density Functional Theory Computational Study

Wan,

Nytka,

Qian

et al. 2023

J. Am. Soc. Mass Spectrom.

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“…The Q-ToF MS is equipped with an ECD cell installed between lens electrode IQ2 and quadrupole q2 ( Figure 1) [28,29]. As such, this instrument can collect ECD spectra of precursor ions isolated by Q1 or it can collect conventional beam-type CID fragmentation spectra by accelerating Q1-isolated precursor ions through the ECD cell and into q2.…”

Section: Dms-ms Instrumentationmentioning

confidence: 99%

Analyzing Glycopeptide Isomers by Combining Differential Mobility Spectrometry with Electron- and Collision-Based Tandem Mass Spectrometry

Campbell¹,

Baba²,

Liu³

et al. 2017

J. Am. Soc. Mass Spectrom.

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Differential mobility spectrometry (DMS) has been employed to separate isomeric species in several studies. Under the right conditions, factors such as separation voltage, temperature, the presence of chemical modifiers, and residence time can combine to provide unique signal channels for isomeric species. In this study, we examined a set of glycopeptide isomers, MUC5AC-3 and MUC5AC-13, which bear an N-acetyl-galactosamine (GalNAc) group on either threonine-3 or threonine-13. When analyzed as a mixture, the resulting MS and MS/MS spectra yield fragmentation patterns that cannot discern these convolved species. However, when DMS is implemented during the analysis of this mixture, two features emerge in the DMS ionogram representing the two glycopeptide isomers. In addition, by locking in DMS parameters at each feature, we could observe several low intensity CID fragments that contain the GalNAc functionality-specific amino acid residues - identifying the DMS separation of each isomer without standards. Besides conventional CID MS/MS, we also implemented electron-capture dissociation (ECD) after DMS separation, and clearly resolved both isomers with this fragmentation method, as well. The electron energy used in these ECD experiments could be tuned to obtain maximum sequence coverage for these glycopeptides; this was critical as these ions were present as doubly protonated species, which are much more difficult to fragment efficiently via electron-transfer dissociation (ETD). Overall, the combination of DMS with electron- or collision-based MS/MS methods provided enhanced separation and sequence coverage for these glycopeptide isomers. Graphical Abstract ᅟ.

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“…C: The acyl chain has two carbon-carbon double bonds at n-6 and n-9. [M- H+O 2 ] •+ is a product of a radical-ion, neutral reaction from the hydrogen lost precursor species, which is often observed in ExD (16).…”

Section: Modified Sms In Brain Smmentioning

confidence: 99%

In-depth sphingomyelin characterization using electron impact excitation of ions from organics and mass spectrometry

Baba

Campbell

Blanc

et al. 2016

Journal of Lipid Research

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This article is available online at http://www.jlr.org the total number of double bonds that comprise the lipid backbone and the acyl group (3). Molecular species-specific information such as backbone type (sphinganine, sphingosine, and sphingadiene with different carbon chain lengths) and the structure of the amide-linked acyl chains (i.e., carbon chain length and the number and stereo-configuration of double bonds) are not provided in a typical CID MS/MS spectrum. The analysis of glycerophospholipids by CID also provides limited structural information and requires polarity switching to identify both the phospholipid class and the fatty acid composition (5-7). In order to fully characterize the structure of lipids, a different fragmentation technique is needed. Recently, Campbell and Baba (8) reported a "nearly" complete identification method of phosphatidylcholines (PCs) using electron-induced dissociation or electron impact excitation of ions from organics (EIEIO) (9) in a branched radio-frequency electron-ion reaction device (10) (referred to as ExD cell in this work). Using EIEIO to fragment glycerophospholipids, information regarding lipid class (or head group), acyl chain length, the number and location of double bonds, and the regioisomeric structure were obtained in a single experiment in the positive ion mode. Using an alternative fragmentation method, Deimler, Sander, and Jackson (4) recently reported a radical induced dissociation of PCs using bombardment of metastable helium atoms (MAD-MS). These reports on novel approaches to structural elucidation of glycerophospholipids suggest that characterization of other lipid categories, such as SM, may be improved by alternative fragmentation strategies to CID.In this study, we applied EIEIO to SM structural characterization using a branched ion trap (10) installed in a Abstract Electron impact excitation of ions from organics (EIEIO), also referred to as electron-induced dissociation, was applied to singly charged SM molecular species in the gas phase. Using ESI and a quadrupole TOF mass spectrometer equipped with an electron-ion reaction device, we found that SMs fragmented sufficiently to identify their lipid class, acyl group structure, and the location of double bond(s). Using this technique, nearly 200 SM molecular species were found in four natural lipid extracts: bovine milk, porcine brain, chicken egg yolk, and bovine heart. In addition to the most common backbone, d18:1, sphingosines with a range of carbon chain lengths, sphingadienes, and some sphinganine backbones were also detected. Modifications in natural SMs were also identified, including addition of iodine/methanol across a carbon-carbon double bond. This unparalleled new approach to SM analysis using EIEIO-MS shows promise as a unique and powerful tool for structural characterization.-Baba, T., J. L. Campbell, J. C. Y. Le Blanc, and P. R. S. Baker. In-depth sphingomyelin characterization using electron impact excitation of ions from organics and mass spectrometry. J. Lipid Res. 2016. 57: ...

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Capturing Polyradical Protein Cations after an Electron Capture Event: Evidence for their Stable Distonic Structures in the Gas Phase

Cited by 5 publications

References 32 publications

Do d(GCGAAGC) Cations Retain the Hairpin Structure in the Gas Phase? A Cyclic Ion Mobility Mass Spectrometry and Density Functional Theory Computational Study

Do d(GCGAAGC) Cations Retain the Hairpin Structure in the Gas Phase? A Cyclic Ion Mobility Mass Spectrometry and Density Functional Theory Computational Study

Analyzing Glycopeptide Isomers by Combining Differential Mobility Spectrometry with Electron- and Collision-Based Tandem Mass Spectrometry

In-depth sphingomyelin characterization using electron impact excitation of ions from organics and mass spectrometry

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