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1.
The concentration and size distribution of particles ablated from the infrared matrix‐assisted laser desorption/ionization matrix compounds succinic acid (butanedioic acid), α‐cyano‐4‐hydroxycinnamic acid, and glycerol were measured using an aerodynamic particle sizer combined with a scanning mobility particle sizer. The two sizing instruments together had a sizing range to from 10 nm to 20 µm. Thin layers of the matrix compounds were irradiated with fluences between 6.0 and 9.5 kJ/m2 and wavelengths between 2.8 and 3.0 µm. The distribution of particles was characterized by a large concentration of clusters in the 20‐nm‐diameter range and large component of mass in the range of coarse particle with diameters greater than 1 µm. The wavelength dependence revealed a blue shift for the maximum particle production that is attributed to heating and disruption of the hydrogen bonds in the matrix that shifts the absorption to shorter wavelengths. This blue shift has been observed previously in infrared matrix‐assisted laser desorption/ionization. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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Cazares LH Troyer DA Wang B Drake RR Semmes OJ 《Analytical and bioanalytical chemistry》2011,401(1):17-27
Matrix-assisted laser desorption ionization (MALDI) imaging mass spectrometry (IMS) is a powerful tool for the generation
of multidimensional spatial expression maps of biomolecules directly from a tissue section. From a clinical proteomics perspective,
this method correlates molecular detail to histopathological changes found in patient-derived tissues, enhancing the ability
to identify candidates for disease biomarkers. The unbiased analysis and spatial mapping of a variety of molecules directly
from clinical tissue sections can be achieved through this method. Conversely, targeted IMS, by the incorporation of laser-reactive
molecular tags onto antibodies, aptamers, and other affinity molecules, enables analysis of specific molecules or a class
of molecules. In addition to exploring tissue during biomarker discovery, the integration of MALDI-IMS methods into existing
clinical pathology laboratory practices could prove beneficial to diagnostics. Querying tissue for the expression of specific
biomarkers in a biopsy is a critical component in clinical decision-making and such markers are a major goal of translational
research. An important challenge in cancer diagnostics will be to assay multiple parameters in a single slide when tissue
quantities are limited. The development of multiplexed assays that maximize the yield of information from a small biopsy will
help meet a critical challenge to current biomarker research. This review focuses on the use of MALDI-IMS in biomarker discovery
and its potential as a clinical diagnostic tool with specific reference to our application of this technology to prostate
cancer. 相似文献
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A novel MALDI LIFT-TOF/TOF mass spectrometer for proteomics 总被引:7,自引:0,他引:7
Suckau D Resemann A Schuerenberg M Hufnagel P Franzen J Holle A 《Analytical and bioanalytical chemistry》2003,376(7):952-965
A new matrix-assisted laser-desorption/ionization time-of-flight/time-of-flight mass spectrometer with the novel "LIFT" technique (MALDI LIFT-TOF/TOF MS) is described. This instrument provides high sensitivity (attomole range) for peptide mass fingerprints (PMF). It is also possible to analyze fragment ions generated by any one of three different modes of dissociation: laser-induced dissociation (LID) and high-energy collision-induced dissociation (CID) as real MS/MS techniques and in-source decay in the reflector mode of the mass analyzer (reISD) as a pseudo-MS/MS technique. Fully automated operation including spot picking from 2D gels, in-gel digestion, sample preparation on MALDI plates with hydrophilic/hydrophobic spot profiles and spectrum acquisition/processing lead to an identification rate of 66% after the PMF was obtained. The workflow control software subsequently triggered automated acquisition of multiple MS/MS spectra. This information, combined with the PMF increased the identification rate to 77%, thus providing data that allowed protein modifications and sequence errors in the protein sequence database to be detected. The quality of the MS/MS data allowed for automated de novo sequencing and protein identification based on homology searching. 相似文献
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Alexandra van Remoortere René J. M. van Zeijl Nico van den Oever Julien Franck Rémi Longuespée Maxence Wisztorski Michel Salzet André M. Deelder Isabelle Fournier Liam A. McDonnell 《Journal of the American Society for Mass Spectrometry》2010,21(11):1922-1929
MALDI imaging and profiling mass spectrometry of proteins typically leads to the detection of a large number of peptides and
small proteins but is much less successful for larger proteins: most ion signals correspond to proteins of m/z < 25,000. This is a severe limitation as many proteins, including cytokines, growth factors, enzymes, and receptors have
molecular weights exceeding 25 kDa. The detector technology typically used for protein imaging, a microchannel plate, is not
well suited to the detection of high m/z ions and is prone to detector saturation when analyzing complex mixtures. Here we report increased sensitivity for higher
mass proteins by using the CovalX high mass HM1 detector (Zurich, Switzerland), which has been specifically designed for the
detection of high mass ions and which is much less prone to detector saturation. The results demonstrate that a range of different
sample preparation strategies enable higher mass proteins to be analyzed if the detector technology maintains high detection
efficiency throughout the mass range. The detector enables proteins up to 70 kDa to be imaged, and proteins up to 110 kDa
to be detected, directly from tissue, and indicates new directions by which the mass range amenable to MALDI imaging MS and
MALDI profiling MS may be extended. 相似文献
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Matrix-assisted laser desorption ionization mass spectrometry imaging (MALDI MSI) techniques are continually being assessed with a view to improving the quality of information obtained from a given sample. A single tissue section will typically only be analyzed once by MALDI MSI and is then either used for histological staining or discarded. In this study, we explore the idea of repeat analysis of a single tissue section by MALDI MSI as a route toward improving sensitivity, structural characterization, and diversity of detected analyte classes. Repeat analysis of a single tissue section from a fresh frozen mouse brain is investigated with both α-cyano-4-hydroxycinnamic acid (CHCA) and para-nitroaniline (PNA). Repeat analysis is then applied to the acquisition of MALDI MSI and MALDI tandem mass spectrometry imaging employing collision induced dissociation (MS/MS imaging employing CID) from a formalin-fixed mouse brain section. Finally, both lipid and protein data are acquired from the same tissue section via repeat analysis utilizing CHCA, sinapinic acid (SA), and a tissue wash step. PNA was found to outperform CHCA as a matrix for repeat analysis; multiple lipids were identified using MS/MS imaging; both lipid and protein images were successfully acquired from a single tissue section. Figure
Repeat analysis by MALDI MS imaging of a single tissue section is investigated with multiple matrices and tissue washes to provide increased molecular information from a single tissue section 相似文献
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Enhancement of protein sensitivity for MALDI imaging mass spectrometry after chemical treatment of tissue sections 总被引:1,自引:0,他引:1
Seeley EH Oppenheimer SR Mi D Chaurand P Caprioli RM 《Journal of the American Society for Mass Spectrometry》2008,19(8):1069-1077
MALDI imaging mass spectrometry (IMS) has become a valuable tool for the investigation of the content and distribution of molecular species in tissue specimens. Numerous methodological improvements have been made to optimize tissue section preparation and matrix deposition protocols, as well as MS data acquisition and processing. In particular for proteomic analyses, washing the tissue sections before matrix deposition has proven useful to improve spectral qualities by increasing ion yields and the number of signals observed. We systematically explore here the effects of several solvent combinations for washing tissue sections. To minimize experimental variability, all of the measurements were performed on serial sections cut from a single mouse liver tissue block. Several other key steps of the process such as matrix deposition and MS data acquisition and processing have also been automated or standardized. To assess efficacy, after each washing procedure the total ion current and number of peaks were counted from the resulting protein profiles. These results were correlated to on-tissue measurements obtained for lipids. Using similar approaches, several selected washing procedures were also tested for their ability to extend the lifetime as well as revive previously cut tissue sections. The effects of these washes on automated matrix deposition and crystallization behavior as well as their ability to preserve tissue histology were also studied. Finally, in a full-scale IMS study, these washing procedures were tested on a human renal cell carcinoma biopsy. 相似文献
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Puolitaival SM Burnum KE Cornett DS Caprioli RM 《Journal of the American Society for Mass Spectrometry》2008,19(6):882-886
A fast and simple, solvent-free matrix deposition protocol was developed for positive ionization mode phospholipid analysis in tissues. Finely ground 2,5-dihydroxybenzoic acid was deposited onto sagittal mouse brain sections using a dry-coating technique, in which solid matrix particles were filtered directly onto the tissue through a 20-microm stainless steel sieve. Phospholipid signals were obtained directly off these sections, allowing acquisition of high-resolution MS images. These images were compared to those from serial sections that were spray-coated with a thin-layer chromatography (TLC) reagent sprayer. Signals obtained from the dry matrix deposition method were comparable to those from spray-coated sections, producing identical localization patterns with a simpler and faster sample preparation with virtually no analyte delocalization. This approach was found to yield highly reproducible results, eliminating much of the variance caused by operator differences, and making it an attractive alternative to the currently used matrix application methods. 相似文献
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Yihsuan S. Tsai Alexander Scherl Jason L. Shaw C. Logan MacKay Scott A. Shaffer Patrick R. R. Langridge-Smith David R. Goodlett 《Journal of the American Society for Mass Spectrometry》2009,20(11):2154-2166
We present a precursor ion independent top-down algorithm (PIITA) for use in automated assignment of protein identifications
from tandem mass spectra of whole proteins. To acquire the data, we utilize data-dependent acquisition to select protein precursor
ions eluting from a C4-based HPLC column for collision induced dissociation in the linear ion trap of an LTQ-Orbitrap mass
spectrometer. Gas-phase fractionation is used to increase the number of acquired tandem mass spectra, all of which are recorded
in the Orbitrap mass analyzer. To identify proteins, the PIITA algorithm compares deconvoluted, deisotoped, observed tandem
mass spectra to all possible theoretical tandem mass spectra for each protein in a genomic sequence database without regard
for measured parent ion mass. Only after a protein is identified, is any difference in measured and theoretical precursor
mass used to identify and locate post-translation modifications. We demonstrate the application of PIITA to data generated
via our wet-lab approach on a Salmonella typhimurium outer membrane extract and compare these results to bottom-up analysis. From these data, we identify 154 proteins by top-down
analysis, 73 of which were not identified in a parallel bottom-up analysis. We also identify 201 unique isoforms of these
154 proteins at a false discovery rate (FDR) of <1%. 相似文献
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Matrix assisted laser desorption/ionization (MALDI) applications, such as proteomics, genomics, clinical profiling and MALDI imaging, have created a growing demand for faster instrumentation. Since the commonly used nitrogen lasers have throughput and life span limitations, diode-pumped solid-state lasers are an alternative. Unfortunately this type of laser shows clear performance limitations in MALDI in terms of sensitivity, resolution and ease of use, for applications such as thin-layer sample preparations, acceptance of various matrices (e.g. DHB for glycopeptides) and MALDI imaging. While it is obvious that the MALDI process has some dependence on the characteristics of the laser used, it is unclear which features are the most critical in determining laser performance for MALDI. In this paper we show, for the first time, that a spatially structured laser beam profile in lieu of a Gaussian profile is of striking importance. This result enabled us to design diode-pumped Nd : YAG lasers that on various critical applications perform as well for MALDI as the nitrogen lasers and in some respects even better. The modulation of the beam profile appears to be a new parameter for optimizing the MALDI process. In addition, the results trigger new questions directing us to a better understanding of the MALDI process. 相似文献
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Bernd Enthaler Maria Trusch Markus Fischer Claudius Rapp Julia K. Pruns Jens-Peter Vietzke 《Analytical and bioanalytical chemistry》2013,405(4):1159-1170
Matrix-assisted laser/desorption ionization (MALDI) mass-spectrometric imaging (MSI), also known as MALDI imaging, is a powerful technique for mapping biological molecules such as endogenous proteins and peptides in human skin tissue sections. A few groups have endeavored to apply MALDI-MSI to the field of skin research; however, a comprehensive article dealing with skin tissue sections and the application of various matrices and enzymes is not available. Our aim is to present a multiplex method, based on MALDI-MSI, to obtain the maximum information from skin tissue sections. Various matrices were applied to skin tissue sections: (1) 9-aminoacridine for imaging metabolites in negative ion mode; (2) sinapinic acid to obtain protein distributions; (3) α-cyano-4-hydroxycinnamic acid subsequent to on-tissue enzymatic digestion by trypsin, elastase, and pepsin, respectively, to localize the resulting peptides. Notably, substantial amounts of data were generated from the distributions retrieved for all matrices applied. Several primary metabolites, e.g. ATP, were localized and subsequently identified by on-tissue postsource decay measurements. Furthermore, maps of proteins and peptides derived from on-tissue digests were generated. Identification of peptides was achieved by elution with different solvents, mixing with α-cyano-4-hydroxycinnamic acid, and subsequent tandem mass spectrometry (MS/MS) measurements, thereby avoiding on-tissue MS/MS measurements. Highly abundant peptides were identified, allowing their use as internal calibrants in future MALDI-MSI analyses of human skin tissue sections. Elastin as an endogenous skin protein was identified only by use of elastase, showing the high potential of alternative enzymes. The results show the versatility of MALDI-MSI in the field of skin research. This article containing a methodological perspective depicts the basics for a comprehensive comparison of various skin states. Figure
Matrix-assisted laser/desorption ionization (MALDI) mass-spectrometric imaging (MSI), also known as MALDI imaging, is a powerful technique for mapping biological molecules in human skin tissue sections. In this body of work, a multiplex method, based on MALDI-MSI, is presented to obtain maximum information from skin tissue sections. Therefore, various matrices were applied to skin tissue sections: (1) 9-aminoacridine (9-AA) for imaging small molecules in negative ion mode; (2) sinapinic acid (SA) to obtain protein distributions; (3) α-cyano-4-hydroxycinnamic acid (α-HCHA) subsequent to on-tissue enzymatic digestion by trypsin, elastase, and pepsin, respectively, to localize the resulting peptides. Of note, identification of metabolites was achieved by post-source decay (PSD) MALDI, and proteins were identified subsequent to enzymatic digestion via the resulting peptides which were eluted from the skin tissue section and afterwards analyzed with use of a tandem time-of-flight (ToF) mass spectrometer. The application of alternative enzymes, such as pepsin and elastase, is highlighted within this article 相似文献
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Compound and metabolite distribution measured by MALDI mass spectrometric imaging in whole-body tissue sections 总被引:2,自引:0,他引:2
Markus Stoeckli Dieter Staab Alain Schweitzer 《International journal of mass spectrometry》2007,260(2-3):195
The determination of the compound distribution in laboratory animal tissue in early development is a standard process in pharmaceutical research. While this information is traditionally obtained by means of whole-body autoradiography using radiolabeled compounds, this technology does not distinguish between metabolites and parent compound. The technique described in this article, termed matrix-assisted laser desorption/ionization (MALDI) mass spectrometric imaging, can fill this gap by simultaneously measuring compound and multiple metabolites distributed in whole-body tissue sections, using non-labeled compounds. 相似文献
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Decellularization of intact tissue enables MALDI imaging mass spectrometry analysis of the extracellular matrix 下载免费PDF全文
Megan Gessel Jeffrey M. Spraggins Paul Voziyan Billy G Hudson Richard M Caprioli 《Journal of mass spectrometry : JMS》2015,50(11):1288-1293
Matrix‐assisted laser desorption/ionization imaging mass spectrometry (MALDI IMS) is a powerful molecular mapping technology that offers unbiased visualization of the spatial arrangement of biomolecules in tissue. Although there has been a significant increase in the number of applications employing this technology, the extracellular matrix (ECM) has received little attention, likely because ECM proteins are mostly large, insoluble and heavily cross‐linked. We have developed a new sample preparation approach to enable MALDI IMS analysis of ECM proteins in tissue. Prior to freezing and sectioning, intact tissues are decellularized by incubation in sodium dodecyl sulfate. Decellularization removes the highly abundant, soluble species that dominate a MALDI IMS spectrum while preserving the structural integrity of the ECM. In situ tryptic hydrolysis and imaging of tryptic peptides are then carried out to accommodate the large sizes of ECM proteins. This new approach allows the use of MALDI IMS for identification of spatially specific changes in ECM protein expression and modification in tissue. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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Targeting hepatocytes from liver tissue by laser capture microdissection and proteomics expression profiling 总被引:4,自引:0,他引:4
A tissue proteomics process is presented where hepatocyte cell isolation in combination with two-dimensional (2-D) gel electrophoresis and mass spectrometric identification were used to annotate the liver proteome. Laser microdissection of 8 microm liver tissue sections was performed and protein expression profiling was compared using a variety of quantities of input cells, and gel separation conditions. The 30 microm diameter laser generated the highest protein yields from the polymer coated caps following microsolubilization. We found that 6000 laser pulses (approximately 7200 hepatocytes) were required in order to generate high-resolution gel maps. Within homogeneous tissue samples, this could be accomplished in a total cycle time of 20 min using an automated dissection procedure. Close to 1000 high-quality gel annotations were generated from the corresponding 2-D gel expression profiles which matched closely the corresponding patterns of analytical-scale liver preparations detected by silver staining. 相似文献
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Grove KJ Frappier SL Caprioli RM 《Journal of the American Society for Mass Spectrometry》2011,22(1):192-195
A new sample preparation method for MALDI tissue imaging has been developed for the analysis of low molecular weight compounds
that employs matrix pre-coated MALDI targets. Tissue sections need only to be transferred onto the pre-coated target before
analysis for fast and easy sample preparation. Pre-coated targets have a homogenous matrix coating with uniform crystals of
approximately 1–2 μm and do not require solvents that may lead to analyte delocalization within a tissue section. We report
here the use of matrix pre-coated targets for imaging of lipids, peptides, and pharmaceuticals in tissues. 相似文献
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Anuj R. Shah Jennifer Davidson Matthew E. Monroe Anoop M. Mayampurath William F. Danielson Yan Shi Aaron C. Robinson Brian H. Clowers Mikhail E. Belov Gordon A. Anderson Richard D. Smith 《Journal of the American Society for Mass Spectrometry》2010,21(10):1784-1788
The diverse range of mass spectrometry (MS) instrumentation along with corresponding proprietary and nonproprietary data formats has generated a proteomics community driven call for a standardized format to facilitate management, processing, storing, visualization, and exchange of both experimental and processed data. To date, significant efforts have been extended towards standardizing XML-based formats for mass spectrometry data representation, despite the recognized inefficiencies associated with storing large numeric datasets in XML. The proteomics community has periodically entertained alternate strategies for data exchange, e.g., using a common application programming interface or a database-derived format. However, these efforts have yet to gain significant attention, mostly because they have not demonstrated significant performance benefits over existing standards, but also due to issues such as extensibility to multidimensional separation systems, robustness of operation, and incomplete or mismatched vocabulary. Here, we describe a format based on standard database principles that offers multiple benefits over existing formats in terms of storage size, ease of processing, data retrieval times, and extensibility to accommodate multidimensional separation systems. 相似文献
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Chamrad DC Koerting G Gobom J Thiele H Klose J Meyer HE Blueggel M 《Analytical and bioanalytical chemistry》2003,376(7):1014-1022
Recent developments in proteomics have revealed a bottleneck in bioinformatics: high-quality interpretation of acquired MS data. The ability to generate thousands of MS spectra per day, and the demand for this, makes manual methods inadequate for analysis and underlines the need to transfer the advanced capabilities of an expert human user into sophisticated MS interpretation algorithms. The identification rate in current high-throughput proteomics studies is not only a matter of instrumentation. We present software for high-throughput PMF identification, which enables robust and confident protein identification at higher rates. This has been achieved by automated calibration, peak rejection, and use of a meta search approach which employs various PMF search engines. The automatic calibration consists of a dynamic, spectral information-dependent algorithm, which combines various known calibration methods and iteratively establishes an optimised calibration. The peak rejection algorithm filters signals that are unrelated to the analysed protein by use of automatically generated and dataset-dependent exclusion lists. In the "meta search" several known PMF search engines are triggered and their results are merged by use of a meta score. The significance of the meta score was assessed by simulation of PMF identification with 10,000 artificial spectra resembling a data situation close to the measured dataset. By means of this simulation the meta score is linked to expectation values as a statistical measure. The presented software is part of the proteome database ProteinScape which links the information derived from MS data to other relevant proteomics data. We demonstrate the performance of the presented system with MS data from 1891 PMF spectra. As a result of automatic calibration and peak rejection the identification rate increased from 6% to 44%.Abbreviations 2-DE Two-dimensional gel electrophoresis - MALDI Matrix-assisted laser desorption ionisation - PMF Peptide mass fingerprinting - MS Mass spectrometry - TOF Time of flight 相似文献