Does in-source decay occur independent of the ionization process in matrix-assisted laser desorption?

Takayama, Mitsuo; Tsugita, Akira

doi:10.1016/s1387-3806(98)14202-1

Cited by 54 publications

(77 citation statements)

References 9 publications

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“…The a9 ion was not observed in the C␣-C bond cleavage at the Gly9 residue (G9 of Figure 5c). The lack of a-series ion at the Gly residue can be seen in the MALDI-ISD spectra reported previously [13,16,23]. A structural characteristic of Gly residues compared to other amino-acids is the lack of a ␤-carbon (C ␤ ).…”

Section: Fragmentation Characteristics Of Maldi-isd Except For the N-mentioning

confidence: 69%

“…The MALDI-ISD spectra of peptides also show informative fragments such as a-, b-, and y-series ions, as well as c-and (z ϩ 2)-series ions originating from N-C␣ bond cleavage [23], although resulting ISD spectra often show broadened peaks even when a delayed extraction device and reflectron TOF are used [24]. Using 5-ASA, the fragment ions could be clearly assigned due to the sharpness of the peaks and decreased interference peaks in the MALDI-ISD spectra.…”

Section: Fragmentation Characteristics Of Maldi-isd Except For the N-mentioning

confidence: 99%

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In-source decay and fragmentation characteristics of peptides using 5-aminosalicylic acid as a matrix in matrix-assisted laser desorption/ionization mass spectrometry

Sakakura

Takayama

2010

J. Am. Soc. Mass Spectrom.

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The use of 5-aminosalicylic acid (5-ASA) as a new matrix for in-source decay (ISD) of peptides including mono-and di-phosphorylated peptides in matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) is described. The use of 5-ASA in MALDI-ISD has been evaluated from several standpoints: hydrogen-donating ability, the outstanding sharpness of molecular and fragment ion peaks, and the presence of interference peaks such as metastable peaks and multiply charged ions. The hydrogen-donating ability of several matrices such as ␣-cyano-4-hydroxycinnamic acid (CHCA), 2,5-dihydroxybenzoic acid (2,5-DHB), 1,5-diaminonaphthalene (1,5-DAN), sinapinic acid (SA), and 5-ASA was evaluated by using the peak abundance of a reduction product [M ϩ 2H ϩ H] ϩ to that of non-reduced protonated molecule [M ϩ H] ϩ of the cyclic peptide vasopressin which contains a disulfide bond (S-S). The order of hydrogendonating ability was 1,5-DAN Ͼ 5-ASA Ͼ 2,5-DHB Ͼ SA ϭ CHCA. The chemicals 1,5-DAN and 5-ASA in particular can be classified as reductive matrices. 5-ASA gave peaks with higher sharpness for protonated molecules and fragment ions than other matrices and did not give any interference peaks such as multiply-protonated ions and metastable ions in the ISD mass spectra of the peptides used. Particularly, 1,5-DAN and 5-ASA gave very little metastable peaks. This indicates that 1,5-DAN and 5-ASA are more "cool" than other matrices. The 1,5-DAN and 5-ASA can therefore be termed "reductive cool" matrix. T he role of mass spectrometry (MS) in protein sciences such as proteomics has become increasingly important due to its outstanding sensitivity and rapidity. It is of importance to recognize that the analysis of proteins using MS generally pertains to the analysis of peptides obtained upon enzymatic digestion of proteins. MS coupled to soft ionization methods such as matrix-assisted laser desorption/ionization (MALDI) [1][2][3] and electrospray ionization (ESI) [4,5] have been used to obtain qualitative information for peptide-mass fingerprinting (PMF), amino acid sequencing and analysis of post-translational modifications (PTMs), and quantitative information about protein(s) expressed from a genome [6,7]. The most valuable information for protein identification including PTMs is the amino acid sequences that are available from tandem mass spectrometry and other MS degradation methods.Of the mass spectrometric dissociation methods used for identifying proteins, electron capture dissociation (ECD) [8] and electron-transfer dissociation (ETD) [9] coupled to ESI and in-source decay (ISD) coupled to MALDI [10] have been noted from the standpoint of specific cleavage at the N-C␣ bond on the peptide backbone because conventional methods such as collision-induced dissociation (CID) leads to nonspecific cleavage of the peptide backbone and the loss of PTM functional groups [11]. The nonspecific cleavage gives backbone cleaved fragments such as a-, b-, x-, and y-series ions (Scheme 1 upper [12] and the loss of NH 3 and/or H 2 O from t...

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Section: Fragmentation Characteristics Of Maldi-isd Except For the N-mentioning

confidence: 69%

Section: Fragmentation Characteristics Of Maldi-isd Except For the N-mentioning

confidence: 99%

In-source decay and fragmentation characteristics of peptides using 5-aminosalicylic acid as a matrix in matrix-assisted laser desorption/ionization mass spectrometry

Sakakura

Takayama

2010

J. Am. Soc. Mass Spectrom.

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“…Another characteristic of radical-induced ISD is its independence from the ionization process [30]. Indeed, Takayama et al suggest that basic amino acids near the N-terminus favor production of c-type fragments and basic amino acids near the C-terminus favor production of zand y-type fragments in positive ion mode [31,32]. As ISD is independent of the ionization process, radical-induced ISD fragments are also observed in the negative ion mode according to the ability of the matrix to produce negatively charged molecular ions.…”

Section: Radical-induced Pathwaymentioning

confidence: 99%

MALDI In-Source Decay, from Sequencing to Imaging

Debois

Smargiasso

Demeure

et al. 2012

Topics in Current Chemistry

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Matrix-assisted laser desorption/ionization (MALDI) is now a mature method allowing the identification and, more challenging, the quantification of biopolymers (proteins, nucleic acids, glycans, etc). MALDI spectra show mostly intact singly charged ions. To obtain fragments, the activation of singly charged precursors is necessary, but not efficient above 3.5 kDa, thus making MALDI MS/MS difficult for large species. In-source decay (ISD) is a prompt fragmentation reaction that can be induced thermally or by radicals. As fragments are formed in the source, precursor ions cannot be selected; however, the technique is not limited by the mass of the analyzed compounds and pseudo MS3 can be performed on intense fragments. The discovery of new matrices that enhance the ISD yield, combined with the high sensitivity of MALDI mass spectrometers, and software development, opens new perspectives. We first review the mechanisms involved in the ISD processes, then discuss ISD applications like top-down sequencing and post-translational modifications (PTMs) studies, and finally review MALDI-ISD tissue imaging applications.

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“…The radical-induced ISD fragmentation is independent of the ionization process [11,19] and can be considered as a charge-remote fragmentation [35]. The influence of the peptide sequence of the peptide sequence was studied because, as they are mainly observed as singly charged ions in MALDI, the location of the charge can influence whether N-terminal or Cterminal fragments can be observed [8,19].…”

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confidence: 99%

New advances in the understanding of the in-source decay fragmentation of peptides in MALDI-TOF-MS

Demeure

Gabelica

Pauw

2010

J. Am. Soc. Mass Spectrom.

117

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In-source decay (ISD) is a rapid fragmentation occurring in the matrix-assisted laser desorption/ionization (MALDI) source before the ion extraction. Despite the increasing interest for peptides de novo sequencing by ISD, the influence of the matrix and of the peptide itself is not yet fully understood. Here we compare matrices with high ISD efficiencies to gain deeper insight in the ISD fragmentation process(es). The major ISD fragments are the c-and z-ions, but other types of fragments are also observed, and their origin is studied here. Two main pathways lead to fragmentation in the source: a radical-induced pathway that leads to c-, z-, w-, and d-ions, and a thermally activated pathway that leads to y-, b-, and a-ions. A detailed analysis of the ISD spectra of selected peptides revealed that (1) the extents of the two in-source pathways are differently favored depending on the matrix used, that (2) the presence of a positive/negative charge on the radical-induced fragments is necessary for their observation in positive/negative mode, respectively, and that (3) [4 -9], especially peptides and proteins. In-source decay (ISD) [10,11] is a fragmentation occurring in the MALDI source, rapidly after the laser shot and before the ion extraction. ISD fragments are therefore detected at the correct m/z ratios in MS mode. On the contrary, fragments formed after the ion extraction are not resolved in MS mode, and can only be revealed by MS/MS in dual stage time-of-flight instruments [12], or by a stepwise lowering of the reflectron voltage in the so-called PSD (post source decay) mode [13,14]. ISD of peptides and proteins mainly leads to c-and z-ions [15,16], and the consensus explanation is that those fragments come from a reduction of the parent ion by hydrogen radicals coming from the matrix [17,18]. Nevertheless, other fragments such as a-, b-, and y-ions have also been reported to form in the MALDI source [4, 7-9, 19, 20]. PSD leads mainly to similar fragments as those formed by low-energy collision-induced dissociation (a-, b-, and y-ions) [21,22].Contrary to CID-like fragments, the radical-induced ISD fragments (c-and z-ions) have the advantage of being theoretically not limited in mass. Indeed, in CID experiments, the internal energy received by the peptide is distributed amongst all its degrees of freedom, i.e., they undergo intramolecular vibrational-energy redistribution (IVR). Therefore, the larger the peptide, the less the energy received per degree of freedom, decreasing the fragmentation efficiency. Like in electron capture dissociation (ECD) [23,24], because the production of c-and z-ions results from a radical-driven process that takes place before the completion of the IVR (non-ergodic process), ISD fragmentation efficiency does not depend on the mass of the peptide and allows to sequence larger peptides as well as intact proteins [5,10].In the present work, we address the mechanisms of in-source formation of the different fragment types. The difficulty in addressing these mechanisms comes from the f...

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Does in-source decay occur independent of the ionization process in matrix-assisted laser desorption?

Cited by 54 publications

References 9 publications

In-source decay and fragmentation characteristics of peptides using 5-aminosalicylic acid as a matrix in matrix-assisted laser desorption/ionization mass spectrometry

In-source decay and fragmentation characteristics of peptides using 5-aminosalicylic acid as a matrix in matrix-assisted laser desorption/ionization mass spectrometry

MALDI In-Source Decay, from Sequencing to Imaging

New advances in the understanding of the in-source decay fragmentation of peptides in MALDI-TOF-MS

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