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Gode D, Schmitt C, Engel M, Volmer DA. Screening Dyrk1A inhibitors by MALDI-QqQ mass spectrometry: systematic comparison to established radiometric, luminescence, and LC-UV-MS assays. Anal Bioanal Chem 2014; 406:2841-52. [PMID: 24618988 DOI: 10.1007/s00216-014-7703-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Revised: 02/12/2014] [Accepted: 02/17/2014] [Indexed: 11/26/2022]
Abstract
Enzyme-catalyzed reactions play key roles in disease pathology, thus making them relevant subjects of therapeutic inhibitor screening experiments. Matrix-assisted laser desorption/ionization (MALDI) assays have been demonstrated to be able to replace established screening approaches. They offer increased sample throughput, but care must be taken to avoid instrumental bias from differences in ionization efficiencies. We compared a MALDI-triple-quadrupole (QqQ) method for the Dyrk1A peptide substrate woodtide to LC-MS, liquid chromatography with ultraviolet detection (LC-UV), luminescence, and radiometric assays. MALDI measurements were performed on a MALDI-QqQ instrument in the multiple-reaction monitoring mode. Different MALDI conditions were investigated to address whether matrix type, sample support, and MRM- or SIM-based detection conditions can be used to accommodate the molar responses of substrate peptide and its phosphorylated form. UV detection served as a reference method. The impact of MALDI matrix on IC50 values was small, even considering that matrix preparations were used that are known to alleviate response differences. IC50 values determined by MALDI were ca. 2-fold lower than those determined by LC-UV. Although MALDI generated lower ion yields for the phosphorylated peptide than for the peptide substrate, we found that a correction of compound potencies was readily possible using correction factors based on unbiased LC-UV results. A thorough method development delivered a robust assay with excellent performance (Z' > 0.91) that was close to that seen for LC-UV.
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Affiliation(s)
- David Gode
- Institute of Bioanalytical Chemistry, Saarland University, 66123, Saarbrücken, Germany
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Zhou LH, Kang GY, Kim KP. A binary matrix for improved detection of phosphopeptides in matrix-assisted laser desorption/ionization mass spectrometry. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2009; 23:2264-2272. [PMID: 19551845 DOI: 10.1002/rcm.4139] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Application of matrix-assisted laser-desorption/ionization mass spectrometry (MALDI MS) to analysis and characterization of phosphopeptides in peptide mixtures may have a limitation, because of the lower ionizing efficiency of phosphopeptides than nonphosphorylated peptides in MALDI MS. In this work, a binary matrix that consists of two conventional matrices of 3-hydroxypicolinic acid (3-HPA) and alpha-cyano-4-hydroxycinnamic acid (CCA) was tested for phosphopeptide analysis. 3-HPA and CCA were found to be hot matrices, and 3-HPA not as good as CCA and 2,5-dihydroxybenzoic acid (DHB) for peptide analysis. However, the presence of 3-HPA in the CCA solution with a volume ratio of 1:1 could significantly enhance ion signals for phosphopeptides in both positive-ion and negative-ion detection modes compared with the use of pure CCA or DHB, the most common phosphopeptide matrices. Higher signal intensities of phosphopeptides could be obtained with lower laser power using the binary matrix. Neutral loss of the phosphate group (-80 Da) and phosphoric acid (-98 Da) from the phosphorylated-residue-containing peptide ions with the binary matrix was decreased compared with CCA alone. In addition, since the crystal shape prepared with the binary matrix was more homogeneous than that prepared with DHB, searching for 'sweet' spots can be avoided. The sensitivity to detect singly or doubly phosphorylated peptides in peptide mixtures was higher than that obtained with pure CCA and as good as that obtained using DHB. We also used the binary matrix to detect the in-solution tryptic digest of the crude casein extracted from commercially available low fat milk sample, and found six phosphopeptides to match the digestion products of casein, based on mass-to-charge values and LIFT TOF-TOF spectra.
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Affiliation(s)
- Li-Hua Zhou
- Department of Molecular Biotechnology, Konkuk University, Seoul 143-701, Korea
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Poth AG, Deeth HC, Alewood PF, Holland JW. Analysis of the Human Casein Phosphoproteome by 2-D Electrophoresis and MALDI-TOF/TOF MS Reveals New Phosphoforms. J Proteome Res 2008; 7:5017-27. [DOI: 10.1021/pr800387s] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Aaron G. Poth
- Institute for Molecular Bioscience and School of Land, Crop and Food Sciences, The University of Queensland, Brisbane, 4072, Australia
| | - Hilton C. Deeth
- Institute for Molecular Bioscience and School of Land, Crop and Food Sciences, The University of Queensland, Brisbane, 4072, Australia
| | - Paul F. Alewood
- Institute for Molecular Bioscience and School of Land, Crop and Food Sciences, The University of Queensland, Brisbane, 4072, Australia
| | - John W. Holland
- Institute for Molecular Bioscience and School of Land, Crop and Food Sciences, The University of Queensland, Brisbane, 4072, Australia
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Chen CT, Chen YC. A two-matrix system for MALDI MS analysis of serine phosphorylated peptides concentrated by Fe3O4/Al2O3 magnetic nanoparticles. JOURNAL OF MASS SPECTROMETRY : JMS 2008; 43:538-541. [PMID: 18074332 DOI: 10.1002/jms.1353] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
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Li Y, Lin H, Deng C, Yang P, Zhang X. Highly selective and rapid enrichment of phosphorylated peptides using gallium oxide-coated magnetic microspheres for MALDI-TOF-MS and nano-LC-ESI-MS/MS/MS analysis. Proteomics 2008; 8:238-49. [PMID: 18081192 DOI: 10.1002/pmic.200700454] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
In this work, we present, to our knowledge, the first demonstration of the utility of iron oxide magnetic microspheres coated with gallium oxide for the highly selective enrichment of phosphopeptide prior to mass spectrometric analysis. These microspheres that we prepared not only have a shell of gallium oxide, giving them a high-trapping capacity for the phosphopeptides, but also their magnetic property enables easy isolation by positioning an external magnetic field. Tryptic digest products of phosphoproteins including beta-casein, ovalbumin, casein, as well as five protein mixtures were used as the samples to exemplify the feasibility of this approach. In very short time (only 0.5 min), phosphopeptides sufficient for characterization by MALDI-TOF-MS were selectively enriched by the Ga(2)O(3)-coated Fe(3)O(4) microspheres. The performance of the Ga(2)O(3)-coated Fe(3)O(4) microspheres were further compared with Fe(3+)-immobilized magnetic silica microspheres, commercial Fe(3+)-IMAC resin, and TiO2 beads for enrichment of peptides originating from tryptic digestion of beta-casein and BSA with a molar ratio of 1:50, and the results proved a stronger selective ability of Ga(2)O(3)-coated Fe(3)O(4) microspheres over the other materials. Finally, the Ga(2)O(3)-coated Fe(3)O(4) microspheres were successfully utilized for enrichment of phosphopeptides from digestion products of rat liver extract. All results show that Ga(2)O(3)-coated Fe(3)O(4) microsphere is an effective material for selective isolation and concentration of phosphopeptides.
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Affiliation(s)
- Yan Li
- Department of Chemistry, Institute of Biomedical Sciences, Fudan University, Shanghai, China
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Li Y, Liu Y, Tang J, Lin H, Yao N, Shen X, Deng C, Yang P, Zhang X. Fe3O4@Al2O3 magnetic core–shell microspheres for rapid and highly specific capture of phosphopeptides with mass spectrometry analysis. J Chromatogr A 2007; 1172:57-71. [DOI: 10.1016/j.chroma.2007.09.062] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2007] [Revised: 09/20/2007] [Accepted: 09/26/2007] [Indexed: 10/22/2022]
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Kleinnijenhuis AJ, Kjeldsen F, Kallipolitis B, Haselmann KF, Jensen ON. Analysis of histidine phosphorylation using tandem MS and ion-electron reactions. Anal Chem 2007; 79:7450-6. [PMID: 17822303 DOI: 10.1021/ac0707838] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Phosphorylation of proteins is essential in intracellular signal transduction pathways in eukaryotic and prokaryotic cells. Histidine phosphorylation plays an important role in two-component signal transduction in bacteria. In this study, we describe the characterization of a synthetic histidine-phosphorylated peptide with four different mass spectrometric (MS) fragmentation techniques: Collision-induced dissociation (CID), electron capture dissociation, electron-transfer dissociation, and electron detachment dissociation. Furthermore, LC-MS methods were developed to detect histidine-phosphorylated peptides, which are acid-labile, in more complex samples. From these results, we concluded that nonacidic solvent systems or fast LC methods provide the best conditions for separation of histidine-phosphorylated peptides prior to electrospray ionization mass spectrometry analysis. Electron-based fragmentation methods should be used for determination of histidine phosphorylation sites, since CID results in very facile phosphate-related neutral losses. The developed LC-MS/MS methods were successfully applied to a tryptic digest of the cytoplasmic part of the histidine kinase EnvZ, which was in vitro autophosphorylated. Finally, a new method is described for nonretentive solid-phase extraction of histidine-phosphorylated peptides using polymeric Strata-X microcolumns.
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Affiliation(s)
- Anne J Kleinnijenhuis
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark
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Current literature in mass spectrometry. JOURNAL OF MASS SPECTROMETRY : JMS 2007; 42:689-700. [PMID: 17474104 DOI: 10.1002/jms.1074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
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Ballard JNM, Lajoie GA, Yeung KKC. Selective sampling of multiply phosphorylated peptides by capillary electrophoresis for electrospray ionization mass spectrometry analysis. J Chromatogr A 2006; 1156:101-10. [PMID: 17188697 DOI: 10.1016/j.chroma.2006.12.025] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2006] [Revised: 11/30/2006] [Accepted: 12/05/2006] [Indexed: 10/23/2022]
Abstract
The ionization of phosphorylated peptides in positive ion mode mass spectrometry is generally less efficient compared with the ionization of their non-phosphorylated counterparts. This can make phosphopeptides much more difficult to detect. One way to enhance the detection of phosphorylated proteins and peptides is by selectively isolating these species. Current approaches of phosphopeptide isolation are based on the favorable interactions of phosphate groups with immobilized metals. While these methods can be effective in the extraction, they can lead to incomplete sample recovery, particularly for the most strongly bound multiply phosphorylated components. A non-sorptive method of phosphopeptide isolation using capillary electrophoresis (CE) was recently reported [Zhang et al., Anal. Chem. 77 (2005) 6078]. The relatively low isoelectric points of phosphopeptides cause them to remain anionic at acidic sample pH. Hence, they can be selectively injected into the capillary by an applied field after the electroosmotic flow (EOF) is suppressed. The technique was previously coupled with matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). In this work, the exploitation of selective sampling in conjugation with electrospray ionization mass spectrometry (ESI-MS) is presented. The transition was not immediately straightforward. A number of major alterations were necessary for ESI interfacing. These adaptations include the choice of a suitable capillary coating for EOF control and the incorporation of organic solvent for efficient ESI. As expected, selective injection of phosphopeptides greatly enhanced the sensitivity of their detection in ESI-MS, particularly for the multiply phosphorylated species that were traditionally most problematic. Furthermore, an electrophoretic separation subsequent to the selective injection of the phosphopeptides was performed prior to analysis by ESI-MS. This allowed us to resolve the multiply phosphorylated peptides present in the samples, predominantly based on the number of phosphorylation sites on the peptides.
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Affiliation(s)
- Jennifer N M Ballard
- Department of Biochemistry, The University of Western Ontario, London, Ontario, Canada
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