Pulse amplitude analysis: a new dimension in single ion time-of-flight mass spectrometry

Bondarenko, Pavel V.; Grant, Patrick G.; Macfarlane, Ronald D.

doi:10.1016/0168-1176(93)03881-l

Cited by 7 publications

(4 citation statements)

References 12 publications

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“…Alternatively, a selected ionic species can be extracted from the QMS and used to bombard a target surface. Previous studies have shown that the number of emitted electrons is correlated with the mass of the impacting ion and that the observation of a well-defined secondary electron number distribution is indicative of a well-focused ion beam consisting of intact protein ions. ,, …”

Section: Experimental and Computational Methodsmentioning

confidence: 99%

Conformation of Highly-Charged Gas-Phase Lysozyme Revealed by Energetic Surface Imprinting

et al. 1998

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We present new results from an energetic surface imprinting method which allows us to outline the general conformation of protein ions in vacuo. Both disulfide-bond-intact and disulfide-bond-reduced gas-phase lysozyme ions were produced by electrospray ionization and were accelerated and impacted onto graphite surfaces. The resulting surface defects, each created by a single incident ion, were imaged with scanning force microscopy. Disulfide-intact lysozyme ions created compact, slightly elliptical hillocks on the surfaces, whereas disulfide-reduced lysozyme produced more oblong, elongated hillocks. By employing a thermal model describing the response of graphite to energy deposited by an elongated incident energetic projectile, we calculated from the hillock sizes for disulfide-reduced lysozyme (Q = 14+) an overall length of 32.1 ± 1.6 nm. This value is close to the length we observe for apomyoglobin (Q = 14+), 35.5 ± 2.4 nm, although apomyoglobin and lysozyme possess significantly different numbers of amino acid residues. Based on these results, we hypothesize that aspects of a protein's native secondary structure are preserved in the gas phase, even if the tertiary structure might be non-native. We have unfolded disulfide-intact lysozyme computationally and find a qualitatively good agreement with the experimentally obtained length of disulfide-intact (Q = 9+) lysozyme.

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Section: Experimental and Computational Methodsmentioning

confidence: 99%

Conformation of Highly-Charged Gas-Phase Lysozyme Revealed by Energetic Surface Imprinting

et al. 1998

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“…Charge discrimination with cryogenic detectors has been demonstrated previously 16,. 17 Other methods for separating charge states, using secondary electron emission,12–14 have much lower resolution, as well as limitations imposed by decreasing electron emission efficiency for detecting larger molecular ions. Though separating ion charge states can be useful, the STJ detector can more finely resolve differences in measured energy, for example, in the deposited energy for different ion species with the same kinetic energy.…”

Section: Resultsmentioning

confidence: 99%

“…Since the secondary electron yield is dependent on the incident velocity of the primary molecular ion, and thus its kinetic energy, secondary electron detectors can also be used to resolve incident ions with different kinetic energies. In particular, this idea has been used to distinguish between ions of different charge states 12–14. This technique was named by the Uppsala group secondary electron resolved mass spectrometry (SERMS) 12.…”

mentioning

confidence: 99%

Investigating ion-surface collisions with a niobium superconducting tunnel junction detector in a time-of-flight mass spectrometer

Westmacott

Fan

Frank

et al. 2000

Rapid Commun. Mass Spectrom.

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The performance of an energy sensitive, niobium superconducting tunnel junction (STJ) detector is investigated by measuring the pulse height produced by impacting molecular and atomic ions at different kinetic energies. Ions are produced by laser desorption and matrix-assisted laser desorption in a time-of-flight mass spectrometer. Our results show that the STJ detector pulse height decreases for increasing molecular ion mass, passes through a minimum at around 2000 Da, and then increases with increasing mass of molecular ions above 2000 Da. The detector does not show a decline in sensitivity for high mass ions as is observed with microchannel plate ion detectors. These detector plus height measurements are discussed in terms of several physical mechanisms involved in an ion-surface collision.

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“…Thus, ions with different masses but the same mass-to-charge ratio (i.e., the same velocity) can be resolved by changing the threshold of the discriminator. This method already has been used in Uppsala and is called secondary electron resolved mass spectrometry [14]; it has been reinvented independently by several other groups [15][16][17]. We have found that the method is useful both to reduce low mass chemical noise in the spectra of proteins [16] and to reduce the "fragmentation" noise in the case of collision-induced dissociation of proteins.…”

Section: Resultsmentioning

confidence: 99%

Effect of ion-molecule collisions in the vacuum chamber of an electrospray time-of-flight mass spectrometer on mass spectra of proteins

Chernushevichfn

Verentchikovfn

Ens

et al. 1996

J. Am. Soc. Mass Spectrom.

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Electrospray ionization spectra of positive multiply charged ions of several proteins with molecular weight from 8565 to 339,100 u were recorded at different pressures of residual gas in the vacuum chamber of an electrospray time-of-flight mass spectrometer. The pressure was varied in the range (0.2 to 5) × 10(-6) torr. The effect of pressure was found to be significant even for the lightest protein investigated (ubiquitin), which resulted in a decrease of both sensitivity and resolution. Investigations of the arrival-time distributions and the energy distributions of ions showed that collision-induced dissociation (CID) of the protein ions in the drift region is the main process responsible for the effect. Several CID cross sections of proteins were estimated from a series of mass spectra recorded at different pressures in the reflecting mode: 1150 Å(2) for cytochrome c (averaged over charge states z = 14-18), 800 Å(2) for lysozyme (z = 8-10), 1840 Å(2) for apomyoglobin (z = 12-25), 800 Å(2) for holomyoglobin (z = 8), and 2500 Å(2) for carbonic anhydrase II (z = 22-35). Several experiments with large proteins in their native conformations and low charge states (m/z 0,000) demonstrate that these ions are less sensitive to high residual gas pressure.

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Pulse amplitude analysis: a new dimension in single ion time-of-flight mass spectrometry

Cited by 7 publications

References 12 publications

Conformation of Highly-Charged Gas-Phase Lysozyme Revealed by Energetic Surface Imprinting

Conformation of Highly-Charged Gas-Phase Lysozyme Revealed by Energetic Surface Imprinting

Investigating ion-surface collisions with a niobium superconducting tunnel junction detector in a time-of-flight mass spectrometer

Effect of ion-molecule collisions in the vacuum chamber of an electrospray time-of-flight mass spectrometer on mass spectra of proteins

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