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Zhang Q, Cai Z, Lin H, Han L, Yan J, Wang J, Ke P, Zhuang J, Huang X. Expression, purification and identification of isotope-labeled recombinant cystatin C protein in Escheichia coli intended for absolute quantification using isotope dilution mass spectrometry. Protein Expr Purif 2020; 178:105785. [PMID: 33152458 DOI: 10.1016/j.pep.2020.105785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2020] [Revised: 09/04/2020] [Accepted: 10/29/2020] [Indexed: 10/23/2022]
Abstract
Isotope-labeled proteins are expected to be used as internal standard proteins in the field of protein quantification by isotope dilution mass spectrometry (ID/MS). To achieve the absolute quantification of Cystatin C (Cys C) based on ID/MS, we aims to obtain 15N isotope-labeled recombinant Cys C (15N-Cys C) protein. Firstly, the Cys C gene was optimized based on the preferred codons of Escherichia coli, and inserted into the pET-28a(+) expression plasmid. Then, the plasmid was transformed into TOP10 and BL21 strains, and 15N-Cys C was expressed in M9 medium using 15N as the only nitrogen source. 15N-Cys C was detected by SDS-PAGE, protein immunoblotting and matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS). The characteristic peptides obtained from 15N-Cys C were analyzed by a Q Exactive Plus MS system. Results showed that 53.06% of the codons were optimized. The codon adaptation index of the Cys C genes increased from 0.31 to 0.95, and the GC content was adjusted from 64.85% to 54.88%. The purity of 15N-Cys C was higher than 95%. MALDI-TOF MS analysis showed that the m/z of 15N-Cys C had changed from 13 449 to 14 850. The characteristic peptides showed that 619.79 m/z (M+2H)2+ was the parent ion of 15N-Cys C and that the secondary ions of 15N-labeled peptides from y+5 to y+9 were 616.27 m/z, 716.33 m/z, 788.39 m/z, 936.43 m/z, and 1052.46 m/z, respectively. In conclusion, we successfully expressed, purified and identified of 15N-Cys C protein in Escheichia coli intended for absolute quantification using ID/MS.
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Affiliation(s)
- Qiaoxuan Zhang
- Department of Laboratory Medicine, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China; Second Clinical Medical College, Guangzhou University of Chinese Medicine, Guangzhou, 510120, China
| | - Zhiliang Cai
- Second Clinical Medical College, Guangzhou University of Chinese Medicine, Guangzhou, 510120, China
| | - Haibiao Lin
- Department of Laboratory Medicine, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Liqiao Han
- Department of Laboratory Medicine, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Jun Yan
- Department of Laboratory Medicine, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Jianbing Wang
- Department of Laboratory Medicine, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Peifeng Ke
- Department of Laboratory Medicine, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Junhua Zhuang
- Department of Laboratory Medicine, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China.
| | - Xianzhang Huang
- Department of Laboratory Medicine, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China.
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Calderón-Celis F, Encinar JR, Sanz-Medel A. Standardization approaches in absolute quantitative proteomics with mass spectrometry. MASS SPECTROMETRY REVIEWS 2018; 37:715-737. [PMID: 28758227 DOI: 10.1002/mas.21542] [Citation(s) in RCA: 96] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Accepted: 06/20/2017] [Indexed: 05/10/2023]
Abstract
Mass spectrometry-based approaches have enabled important breakthroughs in quantitative proteomics in the last decades. This development is reflected in the better quantitative assessment of protein levels as well as to understand post-translational modifications and protein complexes and networks. Nowadays, the focus of quantitative proteomics shifted from the relative determination of proteins (ie, differential expression between two or more cellular states) to absolute quantity determination, required for a more-thorough characterization of biological models and comprehension of the proteome dynamism, as well as for the search and validation of novel protein biomarkers. However, the physico-chemical environment of the analyte species affects strongly the ionization efficiency in most mass spectrometry (MS) types, which thereby require the use of specially designed standardization approaches to provide absolute quantifications. Most common of such approaches nowadays include (i) the use of stable isotope-labeled peptide standards, isotopologues to the target proteotypic peptides expected after tryptic digestion of the target protein; (ii) use of stable isotope-labeled protein standards to compensate for sample preparation, sample loss, and proteolysis steps; (iii) isobaric reagents, which after fragmentation in the MS/MS analysis provide a final detectable mass shift, can be used to tag both analyte and standard samples; (iv) label-free approaches in which the absolute quantitative data are not obtained through the use of any kind of labeling, but from computational normalization of the raw data and adequate standards; (v) elemental mass spectrometry-based workflows able to provide directly absolute quantification of peptides/proteins that contain an ICP-detectable element. A critical insight from the Analytical Chemistry perspective of the different standardization approaches and their combinations used so far for absolute quantitative MS-based (molecular and elemental) proteomics is provided in this review.
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Affiliation(s)
| | - Jorge Ruiz Encinar
- Department of Physical and Analytical Chemistry, University of Oviedo, Oviedo, Spain
| | - Alfredo Sanz-Medel
- Department of Physical and Analytical Chemistry, University of Oviedo, Oviedo, Spain
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Lehmann WD. A timeline of stable isotopes and mass spectrometry in the life sciences. MASS SPECTROMETRY REVIEWS 2017; 36:58-85. [PMID: 26919394 DOI: 10.1002/mas.21497] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Accepted: 01/21/2016] [Indexed: 06/05/2023]
Abstract
This review retraces the role of stable isotopes and mass spectrometry in the life sciences. The timeline is divided into four segments covering the years 1920-1950, 1950-1980, 1980-2000, and 2000 until today. For each period methodic progress and typical applications are discussed. Application of stable isotopes is driven by improvements of mass spectrometry, chromatography, and related fields in sensitivity, mass accuracy, structural specificity, complex sample handling ability, data output, and data evaluation. We currently experience the vision of omics-type analyses, that is, the comprehensive identification and quantification of a complete compound class within one or a few analytical runs. This development is driven by stable isotopes without competition by radioisotopes. In metabolic studies as classic field of isotopic tracer experiments, stable isotopes and radioisotopes were competing solutions, with stable isotopes as the long-term junior partner. Since the 1990s the number of metabolic studies with radioisotopes decreases, whereas stable isotope studies retain their slow but stable upward tendency. Unique fields of stable isotopes are metabolic tests in newborns, metabolic experiments in healthy controls, newborn screening for inborn errors, quantification of drugs and drug metabolites in doping control, natural isotope fractionation in geology, ecology, food authentication, or doping control, and more recently the field of quantitative omics-type analyses. There, cells or whole organisms are systematically labeled with stable isotopes to study proteomic differences or specific responses to stimuli or genetic manipulation. The duo of stable isotopes and mass spectrometry will probably continue to grow in the life sciences, since it delivers reference-quality quantitative data with molecular specificity, often combined with informative isotope effects. © 2016 Wiley Periodicals, Inc. Mass Spec Rev 36:58-85, 2017.
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Affiliation(s)
- Wolf D Lehmann
- German Cancer Research Center (DKFZ), D-69120 Heidelberg, Germany
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Kito K, Okada M, Ishibashi Y, Okada S, Ito T. A strategy for absolute proteome quantification with mass spectrometry by hierarchical use of peptide-concatenated standards. Proteomics 2016; 16:1457-73. [DOI: 10.1002/pmic.201500414] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Revised: 02/18/2016] [Accepted: 03/24/2016] [Indexed: 12/20/2022]
Affiliation(s)
- Keiji Kito
- Department of Life Sciences, School of Agriculture; Meiji University; Kawasaki Japan
| | - Mitsuhiro Okada
- Department of Life Sciences, School of Agriculture; Meiji University; Kawasaki Japan
| | - Yuko Ishibashi
- Department of Life Sciences, School of Agriculture; Meiji University; Kawasaki Japan
| | - Satoshi Okada
- Department of Biochemistry; Kyushu University Graduate School of Medical Science; Fukuoka Japan
| | - Takashi Ito
- Department of Biochemistry; Kyushu University Graduate School of Medical Science; Fukuoka Japan
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5
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Wohlgemuth I, Lenz C, Urlaub H. Studying macromolecular complex stoichiometries by peptide-based mass spectrometry. Proteomics 2015; 15:862-79. [PMID: 25546807 PMCID: PMC5024058 DOI: 10.1002/pmic.201400466] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 11/24/2014] [Accepted: 12/22/2014] [Indexed: 11/11/2022]
Abstract
A majority of cellular functions are carried out by macromolecular complexes. A host of biochemical and spectroscopic methods exists to characterize especially protein/protein complexes, however there has been a lack of a universal method to determine protein stoichiometries. Peptide‐based MS, especially as a complementary method to the MS analysis of intact protein complexes, has now been developed to a point where it can be employed to assay protein stoichiometries in a routine manner. While the experimental demands are still significant, peptide‐based MS has been successfully applied to analyze stoichiometries for a variety of protein complexes from very different biological backgrounds. In this review, we discuss the requirements especially for targeted MS acquisition strategies to be used in this context, with a special focus on the interconnected experimental aspects of sample preparation, protein digestion, and peptide stability. In addition, different strategies for the introduction of quantitative peptide standards and their suitability for different scenarios are compared.
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Affiliation(s)
- Ingo Wohlgemuth
- Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Goettingen, Germany
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6
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Hann S, Dernovics M, Koellensperger G. Elemental analysis in biotechnology. Curr Opin Biotechnol 2015; 31:93-100. [DOI: 10.1016/j.copbio.2014.08.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Accepted: 08/23/2014] [Indexed: 01/25/2023]
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Preparation of heteroelement-incorporated and stable isotope-labeled protein standards for quantitative proteomics. Methods Mol Biol 2014; 1156:337-63. [PMID: 24792000 DOI: 10.1007/978-1-4939-0685-7_23] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
A major obstacle for further development of quantitative proteomics is the lack of accurately quantified protein standards. The following protocol describes innovative methods for the production of stable isotope-labeled protein standards. Their production is achieved by cell-free protein synthesis, which enables simultaneous incorporation of selenomethionine and stable isotope-labeled amino acids. The selenium tag allows sensitive and accurate quantification by inductively coupled plasma mass spectrometry (ICP-MS). The stable isotope label allows internal standardization in mass spectrometry-based proteomics by electrospray ionization-tandem mass spectrometry (ESI-MS/MS). Both label types can be placed within a single protein RISQ standard (recombinant isotope-labeled and selenium quantified) or can be distributed over two types of related RSQ and RIQ standards for the same target protein (recombinant selenium quantified and recombinant isotope-labeled and quantified). The combination of cell-free synthesis as production method with ICP-MS and ESI-MS/MS as detection methods results in protein standards, which are quantified at an outstanding level of accuracy.
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8
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Villanueva J, Carrascal M, Abian J. Isotope dilution mass spectrometry for absolute quantification in proteomics: Concepts and strategies. J Proteomics 2014; 96:184-99. [DOI: 10.1016/j.jprot.2013.11.004] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Accepted: 11/01/2013] [Indexed: 12/25/2022]
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9
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Metrology for metalloproteins—where are we now, where are we heading? Anal Bioanal Chem 2013; 405:5697-723. [DOI: 10.1007/s00216-013-6933-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Revised: 03/18/2013] [Accepted: 03/19/2013] [Indexed: 01/10/2023]
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10
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Reddy PT, Jaruga P, Kirkali G, Tuna G, Nelson BC, Dizdaroglu M. Identification and Quantification of Human DNA Repair Protein NEIL1 by Liquid Chromatography/Isotope-Dilution Tandem Mass Spectrometry. J Proteome Res 2013; 12:1049-61. [DOI: 10.1021/pr301037t] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Prasad T. Reddy
- Biochemical Science Division, National Institute of Standards and Technology, Gaithersburg,
Maryland 20899, United States
| | - Pawel Jaruga
- Biochemical Science Division, National Institute of Standards and Technology, Gaithersburg,
Maryland 20899, United States
| | - Güldal Kirkali
- Biochemical Science Division, National Institute of Standards and Technology, Gaithersburg,
Maryland 20899, United States
| | - Gamze Tuna
- Biochemical Science Division, National Institute of Standards and Technology, Gaithersburg,
Maryland 20899, United States
- Department of Biochemistry, School
of Medicine, Dokuz Eylul University, Izmir,
Turkey
| | - Bryant C. Nelson
- Biochemical Science Division, National Institute of Standards and Technology, Gaithersburg,
Maryland 20899, United States
| | - Miral Dizdaroglu
- Biochemical Science Division, National Institute of Standards and Technology, Gaithersburg,
Maryland 20899, United States
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11
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Boehm ME, Seidler J, Hahn B, Lehmann WD. Site-specific degree of phosphorylation in proteins measured by liquid chromatography-electrospray mass spectrometry. Proteomics 2012; 12:2167-78. [PMID: 22653803 DOI: 10.1002/pmic.201100561] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
This review focuses on quantitative protein phosphorylation analysis based on coverage of both the phosphorylated and nonphosphorylated forms. In this way, site-specific data on the degree of phosphorylation can be measured, generating the most detailed level of phosphorylation status analysis of proteins. To highlight the experimental challenges in this type of quantitative protein phosphorylation analysis, we discuss the typical workflows for mass spectrometry-based proteomics with a focus on the quantitative analysis of peptide/phosphopeptide ratios. We review workflows for measuring site-specific degrees of phosphorylation including the label-free approach, differential stable isotope labeling of analytes, and methods based on the addition of stable isotope labeled peptide/phosphopeptide pairs as internal standards. The discussion also includes the determination of phosphopeptide isoform abundance data for multiply phosphorylated motifs that contain information about the connectivity of phosphorylation events. The review closes with a prospective on the use of intact stable isotope labeled proteins as internal standards and a summarizing discussion of the typical accuracies of the individual methods.
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Affiliation(s)
- Martin E Boehm
- Molecular Structure Analysis, German Cancer Research Center (DKFZ), Heidelberg, Germany
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12
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Winter D, Hung CW, Jaskolla TW, Karas M, Lehmann WD. Enzyme-cleavable tandem peptides for quantitative studies in MS-based proteomics. Proteomics 2012; 12:3470-4. [DOI: 10.1002/pmic.201200290] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Revised: 09/13/2012] [Accepted: 10/01/2012] [Indexed: 11/09/2022]
Affiliation(s)
- Dominic Winter
- Molecular Structure Analysis; German Cancer Research Center; Heidelberg; Germany
| | - Chien-Wen Hung
- Molecular Structure Analysis; German Cancer Research Center; Heidelberg; Germany
| | - Thorsten W. Jaskolla
- Cluster of Excellence Macromolecular Complexes; Institute of Pharmaceutical Chemistry; Goethe-University Frankfurt; Frankfurt; Germany
| | - Michael Karas
- Cluster of Excellence Macromolecular Complexes; Institute of Pharmaceutical Chemistry; Goethe-University Frankfurt; Frankfurt; Germany
| | - Wolf D. Lehmann
- Molecular Structure Analysis; German Cancer Research Center; Heidelberg; Germany
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13
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Sanz-Medel A, Montes-Bayón M, Bettmer J, Luisa Fernández-Sanchez M, Ruiz Encinar J. ICP-MS for absolute quantification of proteins for heteroatom-tagged, targeted proteomics. Trends Analyt Chem 2012. [DOI: 10.1016/j.trac.2012.07.020] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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14
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Pröfrock D, Prange A. Inductively coupled plasma-mass spectrometry (ICP-MS) for quantitative analysis in environmental and life sciences: a review of challenges, solutions, and trends. APPLIED SPECTROSCOPY 2012; 66:843-68. [PMID: 22800465 DOI: 10.1366/12-06681] [Citation(s) in RCA: 142] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
This focal point review provides an overview of recent developments and capabilities of inductively coupled plasma mass spectrometry (ICP-MS) coupled with different separation techniques for applications in the fields of quantitative environmental and bio-analysis. Over the past years numerous technical improvements, which are highlighted in this review, have helped to promote the evolution of ICP-MS to one of the most versatile tools for elemental quantification. In particular, the benefits and possibilities of using state-of-the-art hyphenated ICP-MS approaches for quantitative analysis are demonstrated with a focus on environmental and bio-analytical applications.
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Affiliation(s)
- Daniel Pröfrock
- Helmholtz Zentrum Geesthacht-Zentrum für Material und Küstenforschung, Department Marine Bioanalytical Chemistry, Max-Planck Str. 1, 21502 Geesthacht, Germany.
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15
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QconCATs: design and expression of concatenated protein standards for multiplexed protein quantification. Anal Bioanal Chem 2012; 404:977-89. [DOI: 10.1007/s00216-012-6230-1] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2012] [Revised: 06/22/2012] [Accepted: 06/23/2012] [Indexed: 10/28/2022]
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16
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Bantscheff M, Lemeer S, Savitski MM, Kuster B. Quantitative mass spectrometry in proteomics: critical review update from 2007 to the present. Anal Bioanal Chem 2012; 404:939-65. [PMID: 22772140 DOI: 10.1007/s00216-012-6203-4] [Citation(s) in RCA: 539] [Impact Index Per Article: 44.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Revised: 06/06/2012] [Accepted: 06/15/2012] [Indexed: 02/08/2023]
Abstract
Mass-spectrometry-based proteomics is continuing to make major contributions to the discovery of fundamental biological processes and, more recently, has also developed into an assay platform capable of measuring hundreds to thousands of proteins in any biological system. The field has progressed at an amazing rate over the past five years in terms of technology as well as the breadth and depth of applications in all areas of the life sciences. Some of the technical approaches that were at an experimental stage back then are considered the gold standard today, and the community is learning to come to grips with the volume and complexity of the data generated. The revolution in DNA/RNA sequencing technology extends the reach of proteomic research to practically any species, and the notion that mass spectrometry has the potential to eventually retire the western blot is no longer in the realm of science fiction. In this review, we focus on the major technical and conceptual developments since 2007 and illustrate these by important recent applications.
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Improving the precision of quantitative bottom-up proteomics based on stable isotope-labeled proteins. Anal Bioanal Chem 2012; 404:1079-87. [PMID: 22535440 DOI: 10.1007/s00216-012-6007-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2012] [Revised: 03/29/2012] [Accepted: 03/30/2012] [Indexed: 12/31/2022]
Abstract
Stable isotope dilution-based quantitative proteomics with intact labeled proteins as internal standards in combination with a bottom-up approach, i.e., with quantification on the peptide level, is an established method. To explore the technical precision of this approach, calmodulin-like protein 3 was prepared in non-labeled (light) and SILAC-type labeled (heavy) form by cell-free synthesis, mixed, digested with trypsin, and analyzed by UPLC-ESI-MS. In total, 16 light/heavy peptide pair ratios were determined. Pair-wise comparison of ratios of 12 peptides selected according to S/N ratios >50 revealed that the majority exhibited ratios, which were different at a high level of statistical significance (p < 0.001). HPLC-MALDI-MS ratio data confirmed this observation, thus excluding the ionization method as a source of the observed ratio differences. Variation of the digestion time from 0.25 to 4 h showed that the light/heavy ratios of most peptides decrease with time, indicating a kinetic isotope effect leading to preferred cleavage of light calmodulin-like protein 3. The subset of peptides with statistically identical ratios resulted in an average ratio with a RSD of 1.0 %. The light/heavy ratio calculated on the basis of these peptides probably provides the most accurate molar protein ratio.
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Matic I, Jaffray EG, Oxenham SK, Groves MJ, Barratt CLR, Tauro S, Stanley-Wall NR, Hay RT. Absolute SILAC-compatible expression strain allows Sumo-2 copy number determination in clinical samples. J Proteome Res 2011; 10:4869-75. [PMID: 21830832 PMCID: PMC3189705 DOI: 10.1021/pr2004715] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
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Quantitative mass spectrometry-based proteomics is a vital tool in modern life science research. In contrast to the popularity of approaches for relative protein quantitation, the widespread use of absolute quantitation has been hampered by inefficient and expensive production of labeled protein standards. To optimize production of isotopically labeled standards, we genetically modified a commonly employed protein expression Escherichia coli strain, BL21 (DE3), to construct an auxotroph for arginine and lysine. This bacterial strain allows low-cost, high-level expression of fully labeled proteins with no conversion of labeled arginine to proline. In combination with a fluorescence-based quantitation of standards and nontargeted LC–MS/MS analysis of unfractionated total cell lysates, this strain was used to determine the copy number of a post-translational modifier, small ubiquitin-like modifier (SUMO-2), in HeLa, human sperm, and chronic lymphocytic leukemia cells. By streamlining and improving the generation of labeled standards, this production system increases the breadth of absolute quantitation by mass spectrometry and will facilitate a far wider uptake of this important technique than previously possible. We developed a bacterial expression system optimized for the expression of isotope-labeled protein standards for absolute quantitation by mass spectrometry. This bacterial strain allows low-cost, high-level expression of fully labeled proteins with no conversion of labeled arginine to proline. These labeled proteins can be used to determine the copy number of cellular proteins by quantitative mass spectrometry.
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Affiliation(s)
- Ivan Matic
- Wellcome Trust Centre for Gene Regulation and Expression, College of Life Sciences, University of Dundee, DD1 5EH, Scotland, United Kingdom
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19
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Affiliation(s)
- Xudong Yao
- Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269, USA.
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Eyrich B, Sickmann A, Zahedi RP. Catch me if you can: mass spectrometry-based phosphoproteomics and quantification strategies. Proteomics 2011; 11:554-70. [PMID: 21226000 DOI: 10.1002/pmic.201000489] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2010] [Revised: 09/13/2010] [Accepted: 09/21/2010] [Indexed: 01/16/2023]
Abstract
Phosphorylation of proteins is one of the most prominent PTMs and for instance a key regulator of signal transduction. In order to improve our understanding of cellular phosphorylation events, considerable effort has been devoted to improving the analysis of phosphorylation by MS-based proteomics. Different enrichment strategies for phosphorylated peptides/proteins, such as immunoaffinity chromatography (IMAC) or titanium dioxide, have been established and constantly optimized for subsequent MS analysis. Concurrently, specific MS techniques were developed for more confident identification and phosphorylation site localization. In addition, more attention is paid to the LC-MS instrumentation to avoid premature loss of phosphorylated peptides within the analytical system. Despite major advances in all of these fields, the analysis of phosphopeptides still remains far from being routine in proteomics. However, to reveal cellular regulation by phosphorylation events, not only qualitative information about the phosphorylation status of proteins but also, in particular, quantitative information about distinct changes in phosphorylation patterns upon specific stimulation is mandatory. Thus, yielded insights are of outstanding importance for the emerging field of systems biology. In this review, we will give an insight into the historical development of phosphoproteome analysis and discuss its recent progress particularly regarding phosphopeptide quantification and assessment of phosphorylation stoichiometry.
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Affiliation(s)
- Beate Eyrich
- Leibniz-Institut für Analytische Wissenschaften-ISAS-eV, Dortmund, Germany
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