Ionization techniques for nonvolatile molecules

Vestal, Marvin L.

doi:10.1002/mas.1280020403

Cited by 164 publications

(83 citation statements)

References 88 publications

(6 reference statements)

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“…An alternative ionization possibility for matrix charging that can operate at AP and IP is statistical charging by an explosive fracturing mechanism, including such processes as bubble bursting. Such a mechanism was described by Vestal for particle bombardment and laser ablation of surfaces [29]. He suggested that superheating a surface under vacuum conditions by an energy sudden event resulted in bubbles bursting and forming possibly a supersonic jet.…”

Section: Production Of Charged Droplets or Particles Without An Electmentioning

confidence: 94%

“…Prior to MALDI, Vestal [29] proposed a unified mechanism for ionization of nonvolatile compounds. This mechanism involved charging of droplets during the local disintegration of a surface.…”

Section: The Cluster Mechanism In Maldimentioning

confidence: 99%

“…As noted above, it is well recognized that the cluster model is potentially related to ESI [3,8,32,33] and, thus, multiple charging of clusters may be a possible outcome. However, Vestal's unified ionization model proposed in 1983, based on a charged droplet/cluster model, encompasses fast atom bombardment (FAB), secondary ion mass spectrometry (SIMS), laser desorption (LD), field desorption (FD), and thermospray ionization (TSI), all methods that produce abundant singly charged ions [29]. Karas and Kruger [8] suggested that singly charged ions observed in MALDI originate from clusters by separation of a single ion pair: separation of more than one ion pair was thought to be less favorable, both from a statistical and energetic standpoint.…”

Section: The Cluster Mechanism In Maldimentioning

confidence: 99%

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A Mechanism for Ionization of Nonvolatile Compounds in Mass Spectrometry: Considerations from MALDI and Inlet Ionization

Trimpin

Wang

Inutan

et al. 2012

J. Am. Soc. Mass Spectrom.

111

530

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Mechanistic arguments relative to matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) address observations that predominately singly charged ions are detected. However, recently a matrix assisted laser ablation method, laserspray ionization (LSI), was introduced that can use the same sample preparation and laser as MALDI, but produce highly charged ions from proteins. In MALDI, ions are generated from neutral molecules by the photon energy provided to a matrix, while in LSI ions are produced inside a heated inlet tube linking atmospheric pressure and the first vacuum region of the mass spectrometer. Some LSI matrices also produce highly charged ions with MALDI ion sources operated at intermediate pressure or high vacuum. The operational similarity of LSI to MALDI, and the large difference in charge states observed by these methods, provides information of fundamental importance to proposed ionization mechanisms for LSI and MALDI. Here, we present data suggesting that the prompt and delayed ionization reported for vacuum MALDI are both fast processes relative to producing highly charged ions by LSI. The energy supplied to produce these charged clusters/droplets as well as their size and time available for desolvation are determining factors in the charge states of the ions observed. Further, charged droplets/clusters may be a common link for ionization of nonvolatile compounds by a variety of MS ionization methods, including MALDI and LSI.

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Section: Production Of Charged Droplets or Particles Without An Electmentioning

confidence: 94%

Section: The Cluster Mechanism In Maldimentioning

confidence: 99%

Section: The Cluster Mechanism In Maldimentioning

confidence: 99%

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A Mechanism for Ionization of Nonvolatile Compounds in Mass Spectrometry: Considerations from MALDI and Inlet Ionization

Trimpin

Wang

Inutan

et al. 2012

J. Am. Soc. Mass Spectrom.

111

530

View full text Add to dashboard Cite

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“…The mass spectrometer is a noncommercial instrumcnt (11) that operates on the thermospray ionization principle (33). The vaporizer exit temperature was maintained in the range of 250 to 285C, and the ion source temperature was controlled to produce maximum thermospray ionization response, corresponding to a vapor temperature at the point of ion sampling of 290 to 295°C.…”

mentioning

confidence: 99%

Novel salvage of queuine from queuosine and absence of queuine synthesis in Chlorella pyrenoidosa and Chlamydomonas reinhardtii

et al. 1988

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Partially purified extracts from Chlorella pyrenoidosa and Chlamydomonas reinhardtii catalyze the cleavage of queuosine (Q), a modified 7-deazaguanine nucleoside found exclusively in the first position of the anticodon of certain tRNAs, to queuine, the base of Q. This is the first report of an enzyme that specifically cleaves a 7.deazapurine riboside. Guanosine is not a substrate for this activity, nor is the epoxide a derivative of Q. We also establish that both algae can incorporate exogenously supplied queuine into their tRNA but lack Q-containing tRNA when cultivated in the absence of queuine, indicating that they are unable to synthesize Q de novo. Although no physiological function for Q has been identified in these algae, Q cleavage to queuine would enable algae to generate queuine from exogenous Q in the wild and also to salvage (and recycle) queuine from intracellular tRNA degraded during the normal turnover process. In mammalian cells, queuine salvage occurs by the specific cleavage of queuine from Q-5'-phosphate. The present data also support the hypothesis that plants, like animals, cannot synthesize Q de novo.The modified nucleoside 7-{5-[(4,5-dihydroxy-2-cyclopent-1-yl)amino]methyl}-7-deaza-guanosine, queuosine (Q), and its glycosylated derivatives (Q*) are found in the first position of the anticodons for tRNAs accommodating the amino acids asparagine, aspartic acid, histidine, and tyrosine (reviewed in reference 25). Q is widely distributed in the biosphere, occurring in the tRNA of plants, animals, and eubacteria (25). Bacteria synthesize Q de novo by the irreversible, base-for-base exchange of 7-aminomethyl-7-deazaguanine for guanine in position 34 of the tRNA, after which the cyclopentenediol moiety is added in an unknown fashion (25). The base exchange is catalyzed by tRNAguanine ribosyltransferase (25). Eucaryotes synthesize Q similarly, with the exception that queuine, the base of Q, is exchanged for the guanine in position 34 (22,23,25,31). Animals do not synthesize Q de novo and must obtain queuine from the diet or gut flora, either as the free base or, after degradation of Q-containing (Q+) tRNA, by the specific cleavage of Q-5'-phosphate (Q-5'-P) to queuine (12,18,21,28). It is notable that queuine is not a substrate for Escherichia coli tRNA-guanine ribosyltransferase (25).Animal serum provides queuine to mammalian cells in tissue culture, and this has been exploited to develop a sensitive bioassay for queuine: in the mouse cell line L-M, which is propagated in a serum-free medium, the Q content of tRNA is directly related to the concentration of queuine added to the medium (21, 22). The L-M cell assay has enabled the detection of significant amounts of free queuine in plant and animal products common to the human diet (21). * Corresponding author. Whether plants synthesize queuine de novo or obtain it from exogenous sources has not been established.The present study was prompted by the discovery that extracts from Chlorella pyrenoidosa, which had been cultivated in a defined queuine-f...

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“…It is generally believed that the matrix molecules play a critical role in absorbing the laser photons and distributing the energy in such a way that the embedded analyte molecules would be desorbed and ionized with minimum internal energy. Different models have been proposed [33][34][35][36] to explain the desorption and ionization phenomena under UV-MALDI conditions. In general, it is believed that some sorts of bottleneck [37] exist in the transfer of internal energy from the highly excited matrix moieties to the analyte ions.…”

Section: Fast Vs Metastable Dissociationmentioning

confidence: 99%

A study of fast and metastable dissociations of adenine-thymine binary-base oligonucleotides by using positive-ion MALDI-TOF mass spectrometry

Chan

Fung

2002

J. Am. Soc. Mass Spectrom.

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In the present study, fast and metastable dissociations of a number of adenine-thymine binary-base oligonucleotides under the conditions of UV matrix-assisted laser desorption/ ionization mass spectrometry were investigated. 2-Aminobenzoic acid/ammonium fluoride (ABA/NH 4 F) matrix system was used. The spectra obtained under metastable and fast dissociation conditions exhibit distinctive dissociation products. From the post-source-decay analysis, all oligonucleotides underwent predominantly metastable dissociations at the 3' C-O linkages to form [a n -B] ϩ and w n ϩ complimentary ion series. Based on the present results, the so-called "[w n ϩ80] ϩ " ions were postulated to be the complimentary [z (8Ϫn) AH] ϩ ions rather than the expected phosphate rearrangement products. In addition, these oligonucleotides were found to generate fast dissociation products of b n ϩ , d n ϩ , w n S tructural characterization of short-chain nucleic acids has recently attracted much attention. They can serve as useful tools in molecular biology, as gene probes for diagnosis, or as potential drugs interacting at the level of nucleic acids. Typical short-chain DNA sequencing methods involve the use of the enzymatic or chemical cleavage algorithms [1][2][3] to produce DNA ladder products. The DNA fragments generated are then separated and identified by HPLC or gel electrophoresis. Structural verification of oligonucleotides using these methods is time-consuming and is sometimes impossible for modified oligonucleotides. Recent developments in matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry [4 -9] have stimulated interest in replacing HPLC/gel electrophoresis by mass spectrometry in order to increase the speed and accuracy of the sequence determination. However, this approach still needs the time-consuming chemical or enzymatic reactions for producing sequence specific fragment ladder. A potentially more efficient method would be to obtain the DNA sequence information from fragmentation patterns in mass spectrometry through dissociation. In the present study, we attempt to evaluate the potential use of two rather direct mass spectrometric sequencing methods, namely fast and metastable dissociations for DNA sequence analysis.Fast fragmentation differs from metastable dissociation at the time of bond cleavage after the excitation of the precursor ions. In mass spectrometry, fragments are produced in a much shorter time as compared to the ion extraction time of the mass spectrometer. In the case of time-of-flight mass spectrometer, these fragment ions are therefore registered at their true masses in both linear and reflectron mode of detection. Metastable fragments, on the other hand, are usually formed at a much longer time scale (i.e., Ͼ500 ns) and are formed beyond the ion source region and before reaching the detector. Since the metastable ions are formed with the same velocity of the precursor ions, they are registered at the same mass-to-charge ratio of the precursor ion in a linear TOF instrum...

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Ionization techniques for nonvolatile molecules

Cited by 164 publications

References 88 publications

A Mechanism for Ionization of Nonvolatile Compounds in Mass Spectrometry: Considerations from MALDI and Inlet Ionization

A Mechanism for Ionization of Nonvolatile Compounds in Mass Spectrometry: Considerations from MALDI and Inlet Ionization

Novel salvage of queuine from queuosine and absence of queuine synthesis in Chlorella pyrenoidosa and Chlamydomonas reinhardtii

A study of fast and metastable dissociations of adenine-thymine binary-base oligonucleotides by using positive-ion MALDI-TOF mass spectrometry

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