Laser desorption ionization of proteins with molecular masses exceeding 10,000 daltons

Karas, Michael; Hillenkamp, Franz

doi:10.1021/ac00171a028

Cited by 5,225 publications

(3,305 citation statements)

References 11 publications

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“…The peptides of the combined calibration mixtures 1 and 2 were dissolved in 20% ACN/0.01% TFA to final concentrations of 125 fmol/ L des-arg 1 -bradykinin, 413 fmol/ L angiotensin I, 163 fmol/ L glu 1 -fibrinopeptide B, 6 fmol/ L neurotensin, 250 fmol/ L ACTH (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17), 188 fmol/ L ACTH (18 -39), 375 fmol/ L ACTH , and 438 fmol/ L bovine insulin. The in-solution BSA digest was dissolved in 30% ACN/0.1% TFA to a final concentration of 1 fmol/ L. p-Methoxybenzylpyridinium chloride, which was used for the measurements of the effective temperatures, was dissolved in 20% ACN to final concentrations of 2 and 4 pmol/ L. The initial velocities were measured from 350 fmol bovine insulin as analyte (c ϭ 700 fmol/ L, V ϭ 0.5 L) dissolved in 20% ACN/0.01% TFA; 0.5 L matrix solution (30% ACN/0.1% TFA, c ϭ 45 mM for SA; 70% ACN/0.1% TFA, c ϭ 30 mM for all other matrices) and 0.5 L analyte solution were mixed directly on a polished steel target and air-dried for standard DD preparation.…”

Section: Sample Preparation and Measurementmentioning

confidence: 99%

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Comparison between vacuum sublimed matrices and conventional dried droplet preparation in MALDI-TOF mass spectrometry

Jaskolla

Karas

Roth

et al. 2009

J. Am. Soc. Mass Spectrom.

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The properties of several cinnamic acid compounds used as matrices for matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) were investigated as standard dried droplet (DD) and vacuum sublimed preparations. The differences between both preparation methods were analyzed with regard to matrix grain size, internal ion energy, initial velocity, analyte intensity, and analyte incorporation depth. Some of the used cinnamic acid derivatives exhibit clearly reduced grain sizes as sublimed preparations compared with standard DD approaches. In these cases higher effective temperatures could be measured accompanied by increased analyte intensities, which can be explained by stronger volatilization processes caused by a hindered heat dissipation resulting in a raised analyte transfer into the gas phase. For all sublimed compounds, a strong increase of the initial ion velocity compared with DD preparations could be measured. Higher initial ion velocities correlate with a decrease in internal ion energy which might be attributed to the very uniform crystal morphology exhibited by sublimed compounds. For sublimed matrices without reduced grain size, at least slightly higher analyte intensities could be detected at raised laser fluences. Analyte accumulation in the uppermost matrix layers or the detected higher ion stability can be explanations for these results. Ever increasing numbers of samples call for automation in high-throughput workflows. One of the key areas for progress in automated MALDI analyses consists of improved sample preparation techniques. Numerous efforts have been conducted for improving the preparation step, e.g., the generation of thin uniform matrix layers with high shot-to-shot reproducibility using the aerospray technique by combination of matrix and nitrocellulose [4] or for analysis of synthetic polymers [5]. Also, electrospray deposition and vacuum deposition were reported to yield homogeneous sample preparations with increased analyte intensities [6 -9]. Matrix deposition by sublimation for MALDI imaging has been reported to yield more intense signals with less alkali adducts compared with the electrospray technique [10]. Additionally, sublimed matrix spots deposited on extremely hydrophobic surfaces described in [11][12][13][14] offer a variety of beneficial properties compared with standard dried droplet (DD) preparations: The main advantage of sublimed matrix spots compared with standard DD preparations are higher analyte sensitivities [14 -17]. This is likely related to the formation of considerably smaller crystals and narrow size distribution of thin-film sublimed matrices, such as ␣-cyano-4-hydroxycinnamic acid (CHCA), compared with DD preparations with comparatively large particle sizes and broader size distribution [15]. As a consequence of this, the specific matrix surface area as well as the amount of potential binding places increases compared with standard DD precipitates, which will result in increased analyte binding properties. Additionally, th...

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Section: Sample Preparation and Measurementmentioning

confidence: 99%

“…Analyte accumulation in the uppermost matrix layers or the detected higher ion stability can be explanations for these results. [1][2][3] has evolved into an essential tool for chemical analysis of biomolecules. Ever increasing numbers of samples call for automation in high-throughput workflows.…”

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confidence: 99%

Comparison between vacuum sublimed matrices and conventional dried droplet preparation in MALDI-TOF mass spectrometry

Jaskolla

Karas

Roth

et al. 2009

J. Am. Soc. Mass Spectrom.

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“…M atrix-assisted laser desorption ionization (MALDI) was first introduced by Tanaka and coworkers [1,2] and further developed and improved by Karas and Hillenkamp [3]. The MALDI technique was a major breakthrough in mass spectrometry and it has seen widespread use in chemical and biological research because it offers several key advantages.…”

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confidence: 99%

The analysis of polystyrene and polystyrene aggregates into the mega dalton mass range by cryodetection MALDI TOF MS

Aksenov

Bier

2008

J. Am. Soc. Mass Spectrom.

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Mass spectra of atactic polystyrene were collected into the mega-dalton mass range with a matrix-assisted laser desorption ionization time of flight (MALDI TOF) mass spectrometer, which incorporates a cryodetector comprised of an array of 16 superconducting tunnel junctions (STJ). The STJ cryodetector, theoretically, has no loss in signal response at any mass compared with the reduced signal found at high mass when using a conventional secondaryionization detector. Since ion detection at high m/z is one of the fundamental limitations of mass spectrometry (MS), the cryodetector was used to explore the high m/z limit of the MALDI TOF technique for the analysis of two polymer types. Mass spectra were collected for polystyrene at M n 170, 400, 900, and 2000 kDa and polymethyl methacrylate (PMMA) at M n 62.6 kDa and 153.7 kDa. For polystyrene, the data showed a trend toward increased aggregation and charge state with mass. The M n 2 MDa polystyrene data revealed a peak at m/z 2.2 MegaTh and a charge state analysis revealed that these ions were primarily polystyrene aggregates with a mass of ϳ4 MDa. This aggregate assignment was possible because the cryodetector response allows for the determination of a charge state up to about four. The contribution of each charge state for a selected peak can be determined in this fashion. This analysis revealed the preferential formation of doubly charged even-numbered aggregates over oddnumbered aggregates for high molecular mass polystyrene. A potential mechanism for the aggregation process for doubly charged species is discussed. Karas and Hillenkamp [3]. The MALDI technique was a major breakthrough in mass spectrometry and it has seen widespread use in chemical and biological research because it offers several key advantages. First, it is a relatively "soft" ionization technique that can produce intact low charge state molecular ions at low laser power. Second, like electrospray ionization (ESI), MALDI is suitable for the ionization of large nonvolatile molecules including synthetic polymers and biomacromolecules, which cannot be brought into the gas phase and ionized intact by most other more energetic introduction and ionization techniques. Third, the MALDI technique is more robust than ESI for samples that contain high concentrations of salts and buffers. And finally, because MALDI can be operated in a pulsed ionization mode, it can be conveniently coupled to a time-of-flight (TOF) mass spectrometer. The theory and applications of the MALDI method are reviewed elsewhere [4 -6].It is reasonable to assume that the MALDI technique may have an upper m/z limitation. For example, the laser desorption ionization (LDI) technique, is limited to ϳ1000 Da for intact biological molecules and a few kDa for synthetic polymers [7]. Compared with LDI, MALDI shows reduced fragmentation of macromolecules [8] and the mass range has been extended to several 100 kDa. This extension of the mass range is attributed to the abundant matrix, usually in a ratio of at least 1000:1 with the analyte th...

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“…2 Subsequently, a wide range of matrices, mainly organic in nature, has been utilised. Ions produced from these matrices generally appear in the low-mass region, below m/z 500, and so hinder or prohibit the acquisition of useful data in this mass region.…”

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confidence: 99%

2B or not 2B, that is the question: further investigations into the use of pencil as a matrix for matrix‐assisted laser desorption/ionisation

Langley

Herniman

Townell

2006

Rapid Comm Mass Spectrometry

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The effective use of pencil as a matrix for matrix-assisted laser desorption/ionisation (MALDI) for the study of actinides has previously been demonstrated (Black et al., Rapid Commun. Mass Spectrom. 2006; 20: 1053). Here, the scope of the types of molecules amenable to analysis by this method has been extended, establishing that $90% of a library containing 50 diverse small molecules can be successfully analysed by this technique. Further, the role played by the bulk materials present in the different pencil leads has been investigated and a simple one-step deposition of matrix and calibration materials has been achieved through the fabrication of different calibration pencils (Cali-Pens).

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Laser desorption ionization of proteins with molecular masses exceeding 10,000 daltons

Cited by 5,225 publications

References 11 publications

Comparison between vacuum sublimed matrices and conventional dried droplet preparation in MALDI-TOF mass spectrometry

Comparison between vacuum sublimed matrices and conventional dried droplet preparation in MALDI-TOF mass spectrometry

The analysis of polystyrene and polystyrene aggregates into the mega dalton mass range by cryodetection MALDI TOF MS

2B or not 2B, that is the question: further investigations into the use of pencil as a matrix for matrix‐assisted laser desorption/ionisation

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