| 1. |
- Balakin, AA, et al.
(författare)
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Polymer track membranes for extraction of ions from aqueous solutions at atmospheric pressure
- 2002
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Ingår i: EUROPEAN JOURNAL OF MASS SPECTROMETRY. - : SAGE Publications. - 1469-0667 .- 1751-6838. ; 8:2, s. 79-84
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The possibility of the application of the electromembrane technique for production of ions of biological molecules at atmospheric pressure is demonstrated. This technique has previously only been used for extraction of ions from liquids directly into vacuum. The membrane technique for ion extraction at atmospheric pressure was tested with both time-of-flight and Fourier transform ion cyclotron resonance mass spectrometers. The mass spectra of intact molecular ions obtained from aqueous solutions of peptides and proteins are presented. The possible mechanisms of non-destructive ion extraction are discussed. The new technique is promising for achieving absolute sensitivity (charging every analyte molecule) and for performing spatially-resolved analysis of liquid biological samples.
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| 2. |
- Betancourt, Lázaro H., et al.
(författare)
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Targeting the hydrophilic regions of recombinant proteins by MS via in-solution buffer-free trypsin digestion
- 2020
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Ingår i: European Journal of Mass Spectrometry. - : SAGE Publications. - 1469-0667 .- 1751-6838. ; 26:3, s. 230-237
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Tidskriftsartikel (refereegranskat)abstract
- A desalting step using reversed phase chromatography is a common practice prior to mass spectrometry analysis of proteolytic digests in spite of the detrimental exclusion of the hydrophilic peptides. The detection of such peptides is also important for the complete coverage of protein sequences and the analysis of posttranslational modifications as inquired by regulatory agencies for the commercialization of biotechnological products. The procedure described here, named in-solution buffer-free digestion, simplifies the sample processing and circumvents the above-mentioned limitations by allowing the detection of tryptic hydrophilic peptides via direct ESI-MS analysis. Two DNA recombinant proteins such as HBcAg (hepatitis B core antigen) and fusion VEGF (vascular endothelial growth factor) were analyzed with the proposed in-solution buffer-free digestion allowing the detection of extremely hydrophilic di-, tri- and tetra-peptides, C-terminal His-tail peptide, as well as disulfide-containing peptides. All these molecular species are hardly seen in mass spectrometric analysis using a standard digestion that includes a C18-desalting step. The procedure was also successfully tried on hydrophilic tetra- and hexa-peptides of Ribonuclease B carrying an N-glycosylation site occupied with “high-mannose” N-glycan chains. The in-solution buffer-free digestion constitutes a simple and straightforward approach to analyse the hydrophilic proteolytic peptides which are commonly elusive to the detection by conventional mass spectrometric analysis.
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| 3. |
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| 4. |
- Flensburg, John, et al.
(författare)
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Chemically-assisted fragmentation combined with multi-dimensional liquid chromatography and matrix-assisted laser desorption/ionization post source decay, matrix-assisted laser desorption/ionization tandem time-of flight or matrix-assisted laser desorption/ionization tandem mass spectrometry for improved sequencing of tryptic peptides
- 2005
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Ingår i: European journal of mass spectrometry. - 1469-0667 .- 1751-6838. ; 11:2, s. 169-179
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Tidskriftsartikel (refereegranskat)abstract
- Derivatization of tryptic peptides using an Ettan CAF matrix-assisted laser desorption/ionization (MALDI) sequencing kit in combination with MALDI-post source decay (PSD) is a fast, accurate and convenient way to obtain de novo or confirmative peptide sequencing data. CAF (chemically assisted fragmentation) is based on solid-phase derivatization using a new class of water stable sulfonation agents, which strongly improves PSD analysis and simplifies the interpretation of acquired spectra. The derivatization is performed on solid supports, ZipTip(microC18, limiting the maximum peptide amount to 5 microg. By performing the derivatization in solution enabled the labeling of tryptic peptides derived from 100 microg of protein. To increase the number of peptides that could be sequenced, derivatized peptides were purified using multidimensional liquid chromatography (MDLC) prior to MALDI sequencing. Following the first dimension strong cation exchange (SCX) chromatography step, modified peptides were separated using reversed-phase chromatography (RPC). During the SCX clean up step, positively charged peptides are retained on the column while properly CAF-derivatized peptides (uncharged) are not. A moderately complex tryptic digest, prepared from six different proteins of equimolar amounts, was CAF-derivatized and purified by MDLC. Fractions from the second dimension nano RPC step were automatically sampled and on-line dispensed to MALDI sample plates and analyzed using MALDI mass spectrometry fragmentation techniques. All proteins in the derivatized protein mixture digest were readily identified using MALDI-PSD or MALDI tandem mass spectrometry (MS/MS). More than 40 peptides were unambiguously sequenced, representing a seven-fold increase in the number of sequenced peptides in comparison to when the CAF-derivatized protein mix digest was analyzed directly (no MDLC-separation) using MALDI-PSD. In conclusion, MDLC purification of CAF-derivatized peptides significantly increases the success rate for de novo and confirmative sequencing using various MALDI fragmentation techniques. This new approach is not only applicable to single protein digests but also to more complex digests and could, thus, be an alternative to electrospray ionization MS/MS for peptide sequencing.
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| 5. |
- Griffiths, WJ, et al.
(författare)
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Gas-phase conformation can have an influence on peptide fragmentation
- 2001
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Ingår i: EUROPEAN JOURNAL OF MASS SPECTROMETRY. - : SAGE Publications. - 1469-0667 .- 1751-6838. ; 7:2, s. 89-99
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- In the post-genomic era, mass spectrometry is destined to fulfil a central role in biomedical research, and it is in the area of protein identification that mass spectrometry is now most rapidly expanding. An important identification method is to subject a protein to proteolysis and determine the resulting peptide masses and/or primary structure. From such determinations proteins can be identified. Tandem mass spectrometry (MS/MS) is used to determine primary structure and, for high-throughput identification, computer-based automated strategies are a prerequisite. Computer programs are available for such identifications, where simulated MS/MS spectra of amino acid sequences within a database are generated and compared to experimental spectra. Such algorithms take into account empirical rules for peptide fragmentation, rather than specific gas-phase ion chemistry. For example, fragmentation of each peptide bond is usually considered to be equally facile. In reality, this is not the case. Gas-phase ion chemistry bears an important role in determining the abundance of fragment ions in MS/MS spectra. In this communication, the gas-phase ion chemistry responsible for the facile cleavage between Gln and Gly residues is investigated, particularly in relation to Proline Rich Protein-1.
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| 6. |
- Griffiths, WJ, et al.
(författare)
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High-energy collision-induced dissociation of oxosteroids derivatised to Girard hydrazones
- 2004
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Ingår i: European journal of mass spectrometry (Chichester, England). - : SAGE Publications. - 1469-0667 .- 1751-6838. ; 10:1, s. 63-88
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Tidskriftsartikel (refereegranskat)abstract
- Neutral oxosteroids have been derivatised with Girard T and P hydrazine reagents to give the corresponding Girard hydrazone quaternary ammonium salts. Both Girard T (GT) and Girard P (GP) hydrazones of oxosteroids give very intense [M]+ ion signals in electrospray (ES) mass spectra and fragment within the ES interface and collision cell to give characteristic fragment ions. GT and GP derivatives give informative high-energy collision-induced dissociation spectra, from which the structure of the precursor oxosteroid can be determined. Both charge-remote and charge-mediated mechanisms are responsible for the formation of the fragment ions at high collision-energy.
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| 7. |
- Haselmann, KF, et al.
(författare)
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Can the (M center dot-X) region in electron capture dissociation provide reliable information on amino acid composition of polypeptides?
- 2002
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Ingår i: EUROPEAN JOURNAL OF MASS SPECTROMETRY. - : SAGE Publications. - 1469-0667 .- 1751-6838. ; 8:6, s. 461-469
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- It has been suggested that small losses from reduced peptide molecular species in electron capture dissociation (ECD) could indicate the presence of certain amino acids [H.J. Cooper, R.R. Hudgins, K. Håkansson and A.G. Marshall, J. Am Soc. Mass Spectrom 13, 241 (2002)], similarly to immonium ions in high-energy collision-activated dissociation. The diagnostic value in ECD of the (M•–X) region (1 Da ≤ X ≤ 130 Da) was tested on several synthetic peptides. The insufficiency of the existing knowledge for making correct conclusions on the amino acid composition is demonstrated and new suggestions of the origin of losses are presented based on the “hot hydrogen atom” ECD mechanism. Generally, it is shown that not only protonation but also charge solvation is responsible for the small losses. The origin of 17 Da and 59 Da losses is revisited and a new mechanism for the 18 Da loss is suggested. The loss of a side chain plus a hydrogen atom is found to be a rather reliable indicator of the presence of histidine, tryptophan, tyrosine and, to a lesser degree, threonine. The overall conclusion is that the (M• - X) region does contain information on the amino acid composition, but extraction of this information requires additional studies.
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| 8. |
- Haselmann, KF, et al.
(författare)
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Electronic excitation gives informative fragmentation of polypeptide cations and anions
- 2002
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Ingår i: EUROPEAN JOURNAL OF MASS SPECTROMETRY. - : SAGE Publications. - 1469-0667 .- 1751-6838. ; 8:2, s. 117-121
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- A Fourier transform mass spectrometer is a versatile instrument with a range of available fragmentation techniques. Comparison of polypeptide fragmentation patterns revealed that the techniques involving electronic excitation, such as hot-electron-capture dissociation (HECD) and electron-detachment dissociation (EDD), are even more informative than vibrational excitation (VE) techniques such as collisional activation. For dications of the peptide KIMHASELMANN, 11 eV HECD cleaved all inter-residue links in at least two places, with up to five fragments characterizing each link. For dianions of the same molecule, VE produced only one backbone cleavage whereas EDD gave ten, including five internal cleavage fragments. This is consistent with the general postulate that homogeneous electronic excitation yields more types of cleavage than near-equilibrium processes such as VE.
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| 9. |
- Kraj, Agnieszka, et al.
(författare)
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Fingerprinting of 3, 4-methylenedioxy-methamphetamine markers by desorption/ionization on porous silicon
- 2006
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Ingår i: European journal of mass spectrometry. - : SAGE Publications. - 1469-0667 .- 1751-6838. ; 12:4, s. 253-259
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Tidskriftsartikel (refereegranskat)abstract
- Desorption/ionization on porous silicon (DIOS) is a method which extends the application range of matrix-assisted laser desorption/ ionization time-of-flight mass spectrometry. This technique eliminates matrix background in the low mass range; DIOS is especially advantageous in research on small organic molecules and their metabolites in biological samples. DIOS mass spectrometry was applied for 3, 4-methylenedioxymethamphetamine, (MDMA, Ecstasy) impurities identification. Trace component profiling enables the identification of by-product characteristics for the synthesis route of MDMA. Ecstasy, a synthetic psychoactive drug, is highly popular among young people, and often used as a recreational drug, most commonly during disco parties. MDMA enhances feeling of euphoria by increasing the level of neurotransmitters such as serotonin, dopamine and norepinephrine and causes acute behavioral and psychological effects. MDMA is almost exclusively produced illegally, primarily in Western Europe. The new method for MDMA impurities profiling has been developed to trace the origin of MDMA pills. For comparison and classification of the impurity profiles, principal components analysis was used.
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| 10. |
- Kushnir, Mark M., et al.
(författare)
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Beta-methylamino-L-alanine analysis by liquid chromatography tandem mass spectrometry with iTRAQ as the derivative
- 2009
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Ingår i: European journal of mass spectrometry. - : SAGE Publications. - 1469-0667 .- 1751-6838. ; 15:3, s. 439-443
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Tidskriftsartikel (refereegranskat)abstract
- Amino acid BMMA is produced by cyanobacteria and has been linked to the development of neurodegenerative diseases. We developed a method for quantitative analysis of BMAA in biological samples and plant extracts. The method is utilizing iTRAQ and LC-MS/MS detection using multiple reaction monitoring mode. The method uses 50 pL of sample and has a Limit of quantitation of 300 ng mL(-1), within-run run imprecision below 1%. Using this method we analyzed human serum samples, human cerebrospinal fluid samples and extract of the cycad seed. No BMAA could be detected in the human samples. Content of BMAA in the seed was 50 mg kg(-1).
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| 11. |
- Mirgorodskaya, OA, et al.
(författare)
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Towards the standard-module approach to disulfide-linked polypeptide nanostructures. I. Methodological prerequisites and mass spectrometric characterization of the test two-loop structure
- 2003
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Ingår i: European journal of mass spectrometry (Chichester, England). - : SAGE Publications. - 1469-0667 .- 1751-6838. ; 9:2, s. 139-148
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Tidskriftsartikel (refereegranskat)abstract
- Potentially biologically-active nanostructures can be created from single chains of unmodified peptides by cross-linking different regions of the chain by disulfide bonds and cleaving the chain at specified sites to obtain the final configuration. The availability of techniques for assembly and characterization of such structures was tested on a two-loop structure created from a 21-residue linear peptide. Directed intra-molecular disulfide bond formation was performed by inserting partial sequences favoring intra-molecular S–S bond formation (“loops”) separated by partial sequences disfavoring such a process (“spacers”) into the precursor sequence. Peptide bond cleavage by partial acid hydrolysis at specific sites (GG, NP/DP) inside the loops opened them; the same process in the spacer separated the loops. Synthesis, oxidation and bond cleavage were monitored by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI ToF MS). The hydrolysis fragments of the produced nanostructures were characterized by tandem electrospray ionization Fourier transform mass spectrometry (ESI FT-MS) with collisional and electron capture dissociations. The latter technique was especially useful as it cleaves S–S bonds preferentially. The feasibility of the proposed synthesis approach and the adequacy of the analysis techniques for the test structure were demonstrated.
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| 12. |
- Neupane, Rabin, et al.
(författare)
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Analytical techniques for the characterization of Antibody Drug Conjugates : Challenges and prospects
- 2017
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Ingår i: European journal of mass spectrometry. - : SAGE PUBLICATIONS LTD. - 1469-0667 .- 1751-6838. ; 23:6, s. 417-426
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Tidskriftsartikel (refereegranskat)abstract
- Antibody drug conjugates are increasingly being researched for the treatment of cancer. Accurate and reliable characterization of ADCs is inevitable for their development as potential therapeutic agent. Different analytical techniques have been used in order to decipher heterogeneous nature of antibody drug conjugates, enabling successful characterization. This review will summarize specially three major analytical tools i.e. UV-Vis spectroscopy, liquid chromatography, and mass spectrometry used in characterization of antibody drug conjugates. In this review, major challenges during analysis due to the inherent features of analytical techniques and antibody drug conjugates are summarized along with the modifications intended to address each challenge.
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| 13. |
- Palmblad, Magnus, et al.
(författare)
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A 9.4 T Fourier Transform Ion Cyclotron Resonance Mass Spectrometer : Description and Performance
- 2000
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Ingår i: European journal of mass spectrometry. - 1469-0667 .- 1751-6838. ; 6:3, s. 267-275
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Tidskriftsartikel (refereegranskat)abstract
- 9.4 Tesla Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometers (Bruker BioAPEX-94e) have been installed at the Division of Ion Physics, Uppsala University, and at the Department of Chemistry, University of Warwick, The BioAPEX-94e FT-ICR instrument is built around a high-field, superconducting magnet and a platform with easily interchangeable ion sources [matrix-assisted laser desorption/ionisation (MALDI), secondary ion mass spectrometry (SIMS), electrospray ionisation (ESI) and electron impact/chemical ionisation (EI/CI)I. In this paper a technical description of the instrument is given. Outstanding performance characteristics are demonstrated, notably clear resolution of C59N+ and (C58C2+)-C-13 (mass difference 3.65 mDa) and mass measurement accuracy at the low ppm level. A wide range of applications in Warwick and Uppsala is described, demonstrating the versatility and high performance of the instrument.
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| 14. |
- Ramström, Margareta, et al.
(författare)
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Characterization of γ-carboxylated tryptic peptides by collision-induced dissociation and electron transfer dissociation mass spectrometry.
- 2011
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Ingår i: European journal of mass spectrometry. - : SAGE Publications. - 1469-0667 .- 1751-6838. ; 17:5, s. 497-506
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Tidskriftsartikel (refereegranskat)abstract
- Vitamin K-dependent carboxylation of glutamic acid (Glu) residues into γ-carboxyglutamic acid (Gla) is a post-translational modification essential for normal protein activity of, for example, proteins involved in the blood coagulation system. These proteins may contain as many as 12 sites for γ-carboxylation within a protein sequence of 45 amino acid residues. In the biopharmaceutical industry, powerful analytical techniques are required for identification and localization of modified sites. We here present comparatively easy and rapid methods for studies of Gla-containing proteins using recent technology. The performances of two mass spectrometric fragmentation techniques, collision-induced dissociation (CID) and electron transfer dissociation (ETD), were evaluated with respect to γ-carboxylated peptides, applying on-line LC-ion trap MS. ETD MS has so far not been reported for Gla-containing peptides and the applicability of CID for heavily γ-carboxylated proteins has not been evaluated. The anticoagulant protein, protein C, containing nine Gla-sites, was chosen as a model protein. After tryptic digestion, three peptides containing Gla-residues were detected by MS; a 1.2 kDa fragment containing two Gla-residues, a 4.5 kDa peptide containing seven residues and also the 5.6 kDa tryptic peptides containing all nine Gla-residues. Regarding the shortest peptide, both CID and ETD provided extensive peptide sequencing. For the larger peptides, fragmentation by CID resulted in loss of the 44 Da CO(2)-group, while little additional fragmentation of the peptide chain was observed. In contrast, ETD resulted in comprehensive fragmentation of the peptide backbone. The study demonstrates that the combination of both techniques would be beneficial and complementary for investigation of γ-carboxylated proteins and peptides.
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| 15. |
- Ryding, Mauritz Johan, 1981, et al.
(författare)
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Proton mobility in water clusters
- 2012
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Ingår i: European Journal of Mass Spectrometry. - : SAGE Publications. - 1469-0667 .- 1751-6838. ; 18:2, s. 215-222
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Tidskriftsartikel (refereegranskat)abstract
- Proton mobility in water occurs quickly according to the so-called Grotthuss mechanism. This process and its elementary reaction steps can be studied in great detail by applying suitable mass spectrometric methods to ionic water clusters. Careful choice of suitable core ions in combination with analysis of cluster size trends in hydrogen/deuterium isotope exchange rates allows for detailed insights into fascinating dynamic systems. Analysis of the experiments has been promoted by extensive and systematic quantum chemical model calculations. Detailed low-energy mechanistic pathways for efficient water rearrangement and proton transfer steps, in particular cases along short preformed "wires" of hydrogen bonds, have been identified in consistency with experimental findings.
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| 16. |
- Samgina, T. Yu., et al.
(författare)
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Electrospray ionization tandem mass spectrometry sequencing of novel skin peptides from Ranid frogs containing disulfide bridges
- 2007
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Ingår i: European journal of mass spectrometry. - : SAGE Publications. - 1469-0667 .- 1751-6838. ; 13:2, s. 155-163
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Tidskriftsartikel (refereegranskat)abstract
- Tandem mass spectrometry sequencing, as well as Edman sequencing of peptides belonging to the Rana genus, represents a difficult task due to the presence of a disulfide bridge at the C-terminus and their rather high molecular masses (over 2000Da). The present study throws light upon the sequence of three rather long peptides (more than 20 amino acid residues each) isolated from the skin secretion of Russian frogs, Rana ridibunda and Rana arvalis. This novel aspect involves the fact that the sequences (including two sequences established de novo) were determined exclusively by means of mass spectrometry. A combination of electron capture dissociation (ECD) and collision-induced dissociaiton (CID) data accompanied by exact mass measurements (LTQ Fourier transform ion cyclotron resonance mass spectrometer) facilitated reaching the goal. To overcome the difficulty dealing with disulphide bridges ("Rana box"), reduction of the S-S bond with dithiotreitol followed by derivatization of Cys residues with iodoacetamide was used. The sequence was determined using combined spectral data on y and b series of fragment ions. A multiple mass spectrometry (MS') experiment was also used to elucidate the sequence inside the "Rana box" after cysteine derivatization. Exact mass measurements were used to differentiate between Lys and Gln residues, while characteristic losses of 29 and 43 Da (d and w fragment ions) in CID and ECD experiments allowed us to distinguish between Ile and Leu isomeric acids.
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| 17. |
- Sui, Ping, 1985-, et al.
(författare)
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Neuropeptide imaging in rat spinal cord with MALDI-TOF MS : Method development for the application in pain-related disease studies
- 2017
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Ingår i: European journal of mass spectrometry. - : SAGE Publications. - 1469-0667 .- 1751-6838. ; 23:3, s. 105-115
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Tidskriftsartikel (refereegranskat)abstract
- Spinal cord as a connection between brain and peripheral nervous system is an essential material for studying neural transmission, especially in pain-related research. This study was the first to investigate pain-related neuropeptide distribution in rat spinal cord using a matrix-assisted laser desorption ionization-time of flight imaging mass spectrometry (MALDI TOF MS) approach. The imaging workflow was evaluated and showed that MALDI TOF MS provides efficient resolution and robustness for neuropeptide imaging in rat spinal cord tissue. The imaging result showed that in naive rat spinal cord the molecular distribution of haeme, phosphatidylcholine, substance P and thymosin beta 4 were well in line with histological features. Three groups of pain-related neuropeptides, which are cleaved from prodynorphin, proenkephalin and protachykinin-1 proteins were detected. All these neuropeptides were found predominantly localized in the dorsal spinal cord and each group had unique distribution pattern. This study set the stage for future MALDI TOF MS application to elucidate signalling mechanism of pain-related diseases in small animal models.
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| 18. |
- Sönksen, C. P., et al.
(författare)
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Capture and analysis of low molecular weight ligands by surface plasmon resonance combined with mass spectrometry
- 2001
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Ingår i: European journal of mass spectrometry. - : SAGE Publications. - 1469-0667 .- 1751-6838. ; 7:4-5, s. 385-391
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Tidskriftsartikel (refereegranskat)abstract
- The combination of biomolecular interaction analysis (BIA)by surface plasmon resonance (SPR)and nano-electrospray ionization ion trap mass spectrometry (nanoESI-Ion Trap MS)as well as matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-ToF MS)is demonstrated for the binding of low molecular weight inhibitors (∼ 600 Da) to HIV-1 protease. Inhibitors were captured on sensor chips of a manual or an automated SPR biosensor, to which HIV-1 protease was immobilized. Compounds and buffer components that bound unspecifically to the sensor surface were removed and the inhibitors were eluted in a minimal volume (3 μL), between air bubbles, in order to prevent dispersion of analyte into buffer eluent. Molecular weights were subsequently determined by mass spectrometry, structural information was obtained by MALDI-ToF post-source decay as well as by electrospray ionization tandem mass spectrometry (MS/MS)analysis. Furthermore, competition experiments, using a mixture of different ligands, demonstrated that the peak intensities in the MALDI-ToF spectrum could be used for relative quantification of the amount of the different ligands bound to the immobilized target. Methodology for automated capture and elution of analytes was developed and evaluated.
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| 19. |
- Taube, Amelie Botling, et al.
(författare)
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Proteins in aqueous humor from cataract patients with and without pseudoexfoliation syndrome.
- 2012
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Ingår i: European Journal of Mass Spectrometry. - : SAGE Publications. - 1469-0667 .- 1751-6838. ; 18:6, s. 531-41
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to investigate the protein content in aqueous humor in eyes with and without pseudoexfoliations (PEX) and to evaluate the quantitative proteomics method, isobaric tagging for relative and absolute protein quantification (iTRAQ), in combination with two separation methods followed by matrix-assisted Laser desorption/ionization (MALDI) mass spectrometry and tandem mass spectrometry (MS/MS). During cataract surgery, samples of aqueous humor were collected from 20 eyes with PEX and from 18 control eyes. The relative concentrations of proteins in the pooled samples of ten PEX eyes and eight controls were evaluated after trypsin digestion and Labeling of the peptides with (iTRAQ) reagent. Two separation methods, Liquid chromatography (LC) and capillary electrophoresis (CE) were used, followed by MALDI mass spectrometry and MS/MS. Furthermore, 1D gel electrophoresis was performed on the remaining ten pooled PEX samples and ten control samples. The gel material was separated by nano-liquid chromatography (nano-LC) followed by Linear-ion-trap quadrupole Fourier transformation ion cyclotron resonance (FT-ICR). Fifty four proteins were identified in the LC runs and 24 with CE. The relative concentrations of beta-crystallines B2 and S were raised and those of angiotensinogen and osteopontin Lowered in the PEX sample compared to the control. The trends regarding beta-crystallines B2, angiotensinogen and osteopontin were confirmed by the 1D gel electrophoresis.
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| 20. |
- Tsybin, Youri O., et al.
(författare)
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Capillary Electrophoresis and Electron Capture Dissociation Fourier Transform Ion Cyclotron Resonance Mass Spectrometry for Peptide Mixture and Protein Digest Analysis
- 2002
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Ingår i: European journal of mass spectrometry. - : SAGE Publications. - 1469-0667 .- 1751-6838. ; 8:5, s. 389-395
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Tidskriftsartikel (refereegranskat)abstract
- Recent advances in peptide fragmentation techniques and mass spectrometry have opened up the possibility of combining peptide separation techniques, such as capillary electrophoresis (CE) and capillary liquid chromatography, with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) and electron capture dissociation (ECD) in order to characterize peptide mixtures and protein digests. The results presented in this study show that CE/ECD-FT-ICR MS can be employed for peptide characterization in mixtures of standard peptides and in peptides resulting from the enzymatic digestion of proteins. Furthermore, the technique has potential for the identification and localization of post-translational modifications in peptides and proteins.
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| 21. |
- Wyer, Jean Ann, et al.
(författare)
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On the hydrogen loss from protonated nucleobases after electronic excitation or collisional electron capture
- 2009
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Ingår i: European journal of mass spectrometry. - : SAGE Publications. - 1469-0667 .- 1751-6838. ; 15, s. 681-688
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Tidskriftsartikel (refereegranskat)abstract
- In this work, we have subjected protonated nucleobases MH+ (M = guanine, adenine, thymine, uracil and cytosine) to a range of experiments that involve high-energy (50 keV) collision induced dissociation and electron capture induced dissociation. In the latter case, both neutralisation reionisation and charge reversal were done. For the collision induced dissociation experiments, the ions interacted with O2. In neutral reionisation, caesium atoms were used as the target gas and the protonated nucleobases captured electrons to give neutrals. These were reionised to cations a microsecond later in collisions with O2. In choosing Cs as the target gas, we have assured that the first electron transfer process is favourable (by about 0.1–0.8 eV depending on the base). In the case of protonated adenine, charge reversal experiments (two Cs collisions) were also carried out, with the results corroborating those from the neutralisation reionisation experiments. We find that while collisional excitation of protonated nucleobases in O2 may lead to hydrogen loss with limited probabilities, this channel becomes dominant for electron capture events. Indeed, when sampling reionised neutrals on a microsecond timescale, we see that the ratio between MH+ and M+ is 0.2–0.4 when one electron is captured from Cs. There are differences in these ratios between the bases but no obvious correlation with recombination energies was found.
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| 22. |
- Zhang, R., et al.
(författare)
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Electrospray ionization mass spectrometry studies of rhenium(I) bipyridyl complexes
- 2004
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Ingår i: European journal of mass spectrometry. - : SAGE Publications. - 1469-0667 .- 1751-6838. ; 10:5, s. 599-603
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Tidskriftsartikel (refereegranskat)abstract
- Electrospray ionization mass spectrometry has been employed to study the formation of fragment ions from a series of rhenium(I) bipyridyl complexes [(4,4'-di-(COOEt)(2)-bpy) Re(CO)(3)XPyPF6], where bpy is 2,2'-bipyridine, Py is pyridine and X is H, 4-methyl, 3-methyl, 4-hydroxyl, 3-hydroxyl, 4-amino, or 3-amino of the pyridine ligand. The effects of substituents (X) on the stability of the complexes has been investigated with the increase of fragmentor voltages. For different X substitutents, the stability of the complexes increases as X becomes more electron-donating from H to CH3, OH and NH2. For the same substitutent, the p-substituted pyridines have a stronger stabilizing effect than the corresponding m-substituted ones. Ligand exchange reaction was found in acetonitrile, where the pyridine ligand has been replaced by the solvent, indicated by the formation of [M - PF6 - XPy + MeCN](+) in the fragmentation.
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| 23. |
- Zhao, Ning-Wei, et al.
(författare)
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Characterization and sequence identification of angiotensin II by a novel method involving ultra-fast liquid chromatography assay coupled with matrix-assisted laser desorption/ionization quadrupole ion trap time-of-flight five tandem mass spectrometry analysis
- 2010
-
Ingår i: European journal of mass spectrometry. - : SAGE Publications. - 1469-0667 .- 1751-6838. ; 16:6, s. 663-671
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Tidskriftsartikel (refereegranskat)abstract
- High-throughput proteomics aims to investigate dynamically changing proteins expressed by a full organism, specific tissue or cellular compartment under certain conditions. High-sensitivity mass spectrometry has gradually become a significant tool for characterizing peptides. Here, we analyzed angiotensin II using ultra-fast liquid chromatography (UFLC) coupled with matrix-assisted laser desoprtion/ionization time-of-flight mass spectrometry (MALDI-ToF MS5). First, we applied UFLC in isolating and collecting the angiotensin II, and then Axima-Resonance (MALDI-QIT-ToF MS5) was adopted, which enables collision-induced dissociation-MS5 analysis for fine structural characterization of angiotensin II. Resultant MS, MS2, MS3 and MS4 spectra of interested [M+H](+) ions selected as precursor ions yielded detailed information about the sites of fragmentation as well as the amino acid sequence for angiotensin II; meanwhile, the average deviation between theoretical mass and actually measured mass from MS to MS5 spectra was only 0.32 Da. It indicated that Axima-Resonance was capable of analysing the peptide sequence accurately and providing the corresponding fragmentation information thoroughly, thus suggesting a potential strategy involving UFLC assay coupled with MALDI-QIT-ToF MS5 analysis for high-throughput proteomics studies in the future.
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| 24. |
- Zubarev, RA, et al.
(författare)
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Tandem ionization mass spectrometry of biomolecules
- 2000
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Ingår i: EUROPEAN JOURNAL OF MASS SPECTROMETRY. - : SAGE Publications. - 1469-0667 .- 1751-6838. ; 6:3, s. 235-240
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The novel mass spectrometric technique tandem ionization mass spectrometry (TIMS) employs irradiation of gas-phase even-electron molecular ions of both polarities with >10 eV electrons. This leads to the production of radical molecular cations and anions of large biomolecules. The parent even-electron ions are produced by laser desorption, matrix-assisted laser desorption/ionization (UV and IR) or electrospray ionization and trapped in the cell of a Fourier transform mass spectrometer before irradiation with electrons. For multiply-charged polypeptide cations (up to 16+ for cytochrome c) and di-anions, TIMS produced radical [M + nH]( n + 1)+• cations and previously unreported [M − 2H]−• anions, respectively. Subsequent collisional activation of these species, in contrast to their even electron counterparts, gave only small neutral losses (mainly CO2) regardless of the ionic charge, polarity or lability. This process was rationalized through intramolecular hydrogen atom transfer in cations. Measurements of the threshold energies for electron ejection has now been extended to the protonated porphyrin C76H94N4 [ IE(MH+) = 12.8 ± 0.3 eV] and to multiply-charged polypeptide cations and anions. Serendipitously, it was found that, in the absence of electrons, [M + nH]( n + 1)+• polypeptide cations can also be formed in energetic collisions during the ion isolation process in Fourier transform mass spectrometry.
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| 25. |
- Zubarev, RA, et al.
(författare)
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Towards an understanding of the mechanism of electron-capture dissociation: a historical perspective and modern ideas
- 2002
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Ingår i: EUROPEAN JOURNAL OF MASS SPECTROMETRY. - : SAGE Publications. - 1469-0667 .- 1751-6838. ; 8:5, s. 337-349
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Electron-capture dissociation (ECD) is a new fragmentation technique that utilizes ion–electron recombination reactions. The latter have parallels in other research fields; revealing these parallels helps to understand the ECD mechanism. An overview is given of ECD-related phenomena and of the history of ECD discovery and development. Current views on the ECD mechanism are discussed using both published and new examples.
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| 26. |
- Zuberovic, Aida, et al.
(författare)
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Proteome profiling of human cerebrospinal fluid: exploring the potential of capillary electrophoresis with surface modified capillaries for analysis of complex biological samples.
- 2008
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Ingår i: European journal of mass spectrometry (Chichester, England). - : SAGE Publications. - 1469-0667 .- 1751-6838. ; 14:4, s. 249-60
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Tidskriftsartikel (refereegranskat)abstract
- A bottom-up proteomic approach, based on capillary electrophoresis (CE) in combination with matrix- assisted laser desorption/ionization tandem time-of-flight mass spectrometry (MALDI-ToF/ToF MS), was used to analyze immunoaffinity depleted human cerebrospinal fluid (CSF) and compare it with a non-depleted sample. After enzymatic digestion and desalting, the tryptic peptides were separated by CE using PolyE-323 modified capillaries and fractionated off-line onto MALDI target plates for further analysis by MALDI-MS and MS/MS. The protein profile of the depleted sample was compared with non depleted CSF. Overall, 85 proteins were identified with 95% significance in both samples. The significance scores for proposed biomarkers, such as amyloid-like protein 1 precursor, could be increased up to 12 times after the depletion. Other proteins, often suggested to be related to neurodegenerative diseases, like amyloid beta A4 protein precursor, superoxide dismutase and apolipoprotein E precursor could only be found in the depleted CSF samples. The effect of a derivatization of tryptic peptides with 2- methoxy-4,5-dihydro-1H-imidazole reagent for protein identification with MS was also employed to increase the number of identified proteins and the sequence coverages. The results presented in this study illustrate the benefit of combining a sample pre-fractionation step and a label's ability to enhance the ionization efficiency with the potential of CE using PolyE-323 modified capillaries in the analysis of complex samples. The straight-forward approach that provides speed and simplicity resulting in high-resolution separations and low sample consumption represents an easily applicable separation technique that can serve as a complement to other currently existing analytical approaches needed in modern proteomic analysis of clinically relevant samples.
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| 27. |
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