Fragmentation of B12H11S-R(2−) in electrospray mass spectrometry

Slepukhina, Irina; Duelcks, Thomas; Schiebel, Hans‐Martin; Gabel, Detlef

doi:10.1016/j.jorganchem.2005.01.040

Cited by 10 publications

(11 citation statements)

References 5 publications

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“…We had found previously that ESI-MS is also capable of detecting small amounts of ionic impurities. [7] When alkylation is performed at higher temperatures, partial halogenation of the cluster is found which further corroborates the purity of the substances obtained under mild conditions. 11 B NMR spectra agree with the structure of the cluster; impurities are, however, difficult to detect because of the inherent broadness of the signals.…”

supporting

confidence: 68%

Trialkylammoniododecaborates: Anions for Ionic Liquids with Potassium, Lithium and Protons as Cations

Justus

Rischka

Wishart

et al. 2008

Chemistry A European J

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Herein we report a new class of low-melting ionic liquids (IL) that consist of N,N,N-trialkylammonioundecahydrododecaborates(1-) as the anion and a range of cations. The cations include the common cations of conventional ILs such as tetraalkylammonium, N-alkylpyridinium, and N-methyl-N'-alkylimidazolium. In addition, their salts with lithium, potassium, and proton cations also exist as ILs. Pulse radiolysis studies indicate that the anions do not react with solvated electrons.

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supporting

confidence: 68%

Trialkylammoniododecaborates: Anions for Ionic Liquids with Potassium, Lithium and Protons as Cations

Justus

Rischka

Wishart

et al. 2008

Chemistry A European J

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“…Fragmentation occurred by collision of ions with background gas (nitrogen), where the pressure in this region was ~3 mtorr [4, 49]. Note that the declustering potential was ion optic skimmer 1, therefore when this voltage was increased (as shown in Figure 1), fragmentation of proteins could be induced.…”

Section: Experimental Methodsmentioning

confidence: 99%

Structural characterization of intact proteins is enhanced by prevalent fragmentation pathways rarely observed for peptides

Cobb

Easterling

Agar

2010

J. Am. Soc. Mass Spectrom.

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While collisionally activated dissociation (CAD) pathways for peptides are well characterized, those of intact proteins are not. We systematically assigned CAD product ions of ubiquitin, myoglobin, and bovine serum albumin generated using high-yield, in-source fragmentation. Assignment of Ͼ98% of hundreds of product ions implies that the fragmentation pathways described are representative of the major pathways. Protein dissociation mechanisms were found to be modulated by both source declustering potential and precursor ion charge state. Like peptides, higher charge states of proteins fragmented at lower energies next to Pro, via mobile protons, while lower charge states fragmented at higher energies after Asp and Glu, via localized protons. Unlike peptides, however, predominant fragmentation channels of proteins occurred at intermediate charge states via non-canonical mechanisms and produced extensive internal fragmentation. The non-canonical mechanisms include prominent cleavages Cterminal to Pro and Asn, and N-terminal to Ile, Leu, and Ser; these cleavages, along with internal fragments, led to a 45% increase in sequence coverage, improving the specificity of top-down protein identification. Three applications take advantage of the different mechanisms of protein fragmentation. First, modulation of declustering potential selectively fragments different charge states, allowing the source region to be used as the first stage of a low-resolution tandem mass spectrometer, facilitating pseudo-MS 3 of product ions with known parent charge states. Second, development and integration of automated modulation of ion funnel declustering potential allows users access to a particular fragmentation mechanism, yielding facile cleavage on a liquid chromatography timescale. There are two fundamental differences between the so-called top-down and the traditional bottom-up approaches (bottom-up uses proteolytic peptides of Յ3000 Da) [3]. The first is that top-down methods can provide the mass of the protein and the second is that top-down proteomics methods rely exclusively upon fragments generated in the gas phase, whereas bottom-up methods employ an additional chemical or enzymatic digestion step [3]. Limitations of top-down methods are the upper mass limit (currently at 669 kDa [4] for protein identification) and the efficiency, and understanding of the mechanism of, gas-phase protein fragmentation.Numerous surface-induced dissociation and collisionally activated dissociation (CAD) studies [5][6][7][8][9][10][11][12] characterized peptide fragmentation mechanisms [5], including the comprehensive characterization of fragmentation trends by systematic, large-scale studies [13][14][15]. From these studies arose the "mobile proton model" (and the recent "pathways in competition" model), which state that fragmentation requires the collisionally activated transfer of a proton from a basic site to a less basic site. The positions of amino acids with high structural rigidity and high gas-phase basicity (proline, arginine, histidine,...

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“…Increasing the voltage between the nozzle and the skimmer (V s CID) increases the kinetic energy of the ions passing through this region. This raises the energy of collision between the ions and background gas, eventually causing fragmentation [43].…”

Section: Esi-ms N Analysismentioning

confidence: 99%

“…Then, this ion is accelerated, by applying a high-frequency AC voltage, and collides with a collision gas. The fragmentation ions generated are then detected by a mass scan [43]. The collision energy needed to achieve optimum fragmentation efficiency has been shown to follow a linear correlation with m/z.…”

Section: Esi-ms N Analysismentioning

confidence: 99%

Characterization of primaquine imidazolidin-4-ones with antimalarial activity by electrospray ionization-ion trap mass spectrometry

Vale

Moreira

Gomes

2008

International Journal of Mass Spectrometry

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The extensive characterization by electrospray ionization-ion trap mass spectrometry (ESI-MS n ) of 20 imidazolidin-4-ones derived from the antimalarial primaquine was well obtained. These compounds are being under investigation as potential antimalarials, as they have been previously found to be active against rodent P. berghei malaria and to be highly stable under physiological conditions. Experiments by collision-induced dissociation (CID) in the nozzle-skimmer region or by tandem-MS have shown the title compounds to be remarkably stable. Mechanisms are proposed to explain the major fragmentations observed in ESI-MS n experiments. Overall, this work represents an unprecedented contribution to a deeper insight into imidazolidin-4-one antimalarials based on a classic 8-aminoquinolinic scaffold. Data herein reported and discussed may be an useful guide for future studies on therapeutically relevant molecules possessing either the 8-aminoquinoline or the imidazolidin-4-one motifs.

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Fragmentation of B12H11S-R(2−) in electrospray mass spectrometry

Cited by 10 publications

References 5 publications

Trialkylammoniododecaborates: Anions for Ionic Liquids with Potassium, Lithium and Protons as Cations

Trialkylammoniododecaborates: Anions for Ionic Liquids with Potassium, Lithium and Protons as Cations

Structural characterization of intact proteins is enhanced by prevalent fragmentation pathways rarely observed for peptides

Characterization of primaquine imidazolidin-4-ones with antimalarial activity by electrospray ionization-ion trap mass spectrometry

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