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Wang Q, Gao G, Fang F, Wang Q, Lundquist PK, Sun L. A simple and efficient approach for preparing cationic coating with tunable electroosmotic flow for capillary zone electrophoresis-mass spectrometry-based top-down proteomics. Anal Chim Acta 2024; 1328:343162. [PMID: 39266194 PMCID: PMC11404064 DOI: 10.1016/j.aca.2024.343162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2024] [Revised: 08/20/2024] [Accepted: 08/26/2024] [Indexed: 09/14/2024]
Abstract
BACKGROUND Capillary zone electrophoresis-tandem mass spectrometry (CZE-MS/MS) has become a valuable analytical technique in top-down proteomics (TDP). CZE-MS/MS-based TDP typically employs separation capillaries with neutral coatings (i.e., linear polyacrylamide, LPA). However, issues related to separation resolution and reproducibility remain with the LPA-coated capillaries due to the unavoidable non-specific protein adsorption onto the capillary wall. Cationic coatings can be critical alternatives to LPA coating for CZE-MS/MS-based TDP due to the electrostatic repulsion between the positively charged capillary inner wall and proteoform molecules in the acidic separation buffer. Unfortunately, there are only very few studies using cationic coating-based CZE-MS/MS for TDP studies. RESULTS In this work, we aimed to develop a simple and efficient approach for preparing separation capillaries with a cationic coating, i.e., poly (acrylamide-co-(3-acrylamidopropyl) trimethylammonium chloride [PAMAPTAC]) for CZE-MS/MS-based TDP. The PAMAPTAC coating-based CZE-MS produced significantly better separation resolution of proteoforms compared to the traditionally used LPA-coated approach. It achieved reproducible separation and measurement of a simple proteoform mixture and a complex proteome sample (i.e., a yeast cell lysate) regarding migration time, proteoform intensity, and the number of proteoform identifications. The PAMAPTAC coating-based CZE-MS enabled the detection of large proteoforms (≥30 kDa) from the yeast cell lysate reproducibly without any size-based prefractionation. Interestingly, the mobility of proteoforms using the PAMAPTAC coating can be predicted accurately using a simple semi-empirical model. SIGNIFICANCE The results render the PAMAPTAC coating as a valuable alternative to the LPA coating to advance CZE-MS-based TDP towards high-resolution separation and highly reproducible measurement of proteoforms in complex samples.
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Affiliation(s)
- Qianjie Wang
- Department of Chemistry, Michigan State University, 578 S Shaw Lane, East Lansing, MI, 48824, USA; Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, 48824, USA; Plant Resilience Institute, Michigan State University, East Lansing, MI, 48824, USA
| | - Guangyao Gao
- Department of Chemistry, Michigan State University, 578 S Shaw Lane, East Lansing, MI, 48824, USA
| | - Fei Fang
- Department of Chemistry, Michigan State University, 578 S Shaw Lane, East Lansing, MI, 48824, USA
| | - Qianyi Wang
- Department of Chemistry, Michigan State University, 578 S Shaw Lane, East Lansing, MI, 48824, USA
| | - Peter K Lundquist
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, 48824, USA; Plant Resilience Institute, Michigan State University, East Lansing, MI, 48824, USA
| | - Liangliang Sun
- Department of Chemistry, Michigan State University, 578 S Shaw Lane, East Lansing, MI, 48824, USA.
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2
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Fang F, Xu T, Chien Hagar HT, Hovde S, Kuo MH, Sun L. Pilot Study for Deciphering Post-Translational Modifications and Proteoforms of Tau Protein by Capillary Electrophoresis-Mass Spectrometry. J Proteome Res 2024. [PMID: 39327902 DOI: 10.1021/acs.jproteome.4c00587] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/28/2024]
Abstract
Abnormal accumulation of tau protein in the brain is one pathological hallmark of Alzheimer's disease (AD). Many tau protein post-translational modifications (PTMs) are associated with the development of AD, such as phosphorylation, acetylation, and methylation. Therefore, a complete picture of the PTM landscape of tau is critical for understanding the molecular mechanisms of AD progression. Here, we offered a pilot study of combining two complementary analytical techniques, capillary zone electrophoresis (CZE)-tandem mass spectrometry (MS/MS) and reversed-phase liquid chromatography (RPLC)-MS/MS, for bottom-up proteomics of recombinant human tau-0N3R. We identified 50 phosphorylation sites of tau-0N3R in total, which is about 25% higher than that from RPLC-MS/MS alone. CZE-MS/MS provided more PTM sites (i.e., phosphorylation) and modified peptides of tau-0N3R than RPLC-MS/MS, and its predicted electrophoretic mobility helped improve the confidence of the identified modified peptides. We developed a highly efficient capillary isoelectric focusing (cIEF)-MS technique to offer a bird's-eye view of tau-0N3R proteoforms, with 11 putative tau-0N3R proteoforms carrying up to nine phosphorylation sites and lower pI values from more phosphorylated proteoforms detected. Interestingly, under native-like cIEF-MS conditions, we observed three putative tau-0N3R dimers carrying phosphate groups. The findings demonstrate that CE-MS is a valuable analytical technique for the characterization of tau PTMs, proteoforms, and even oligomerization.
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Affiliation(s)
- Fei Fang
- Department of Chemistry, Michigan State University, 578 S Shaw Lane, East Lansing, Michigan 48824, United States
| | - Tian Xu
- Department of Chemistry, Michigan State University, 578 S Shaw Lane, East Lansing, Michigan 48824, United States
| | - Hsiao-Tien Chien Hagar
- Department of Biochemistry and Molecular Biology, Michigan State University, 603 Wilson Road, Room 401, East Lansing, Michigan 48824, United States
| | - Stacy Hovde
- Department of Biochemistry and Molecular Biology, Michigan State University, 603 Wilson Road, Room 401, East Lansing, Michigan 48824, United States
| | - Min-Hao Kuo
- Department of Biochemistry and Molecular Biology, Michigan State University, 603 Wilson Road, Room 401, East Lansing, Michigan 48824, United States
| | - Liangliang Sun
- Department of Chemistry, Michigan State University, 578 S Shaw Lane, East Lansing, Michigan 48824, United States
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3
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Zhong J, Song X, Wang S. FREE: Enhanced Feature Representation for Isotopic Envelope Evaluation in Top-Down Mass Spectra Deconvolution. Anal Chem 2024; 96:12602-12615. [PMID: 39037184 DOI: 10.1021/acs.analchem.4c00152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/23/2024]
Abstract
The aim of deconvolution of top-down mass spectra is to recognize monoisotopic peaks from the experimental envelopes in raw mass spectra. So accurate assessment of similarity between theoretical and experimental envelopes is a critical step in mass spectra data deconvolution. Existing evaluation methods primarily rely on intensity differences and m/z similarity, potentially lacking a comprehensive assessment. To overcome this constraint and facilitate a comprehensive and refined assessment of the similarity between theoretical and experimental envelopes, there exists an imperative to systematically explore and identify increasingly efficacious features for assessing this correspondence. We present enhanced feature representation for isotopic envelope evaluation (FREE) that derives diverse feature representations, encapsulating fundamental physical attributes of envelopes, including peak intensity and envelope shape. We trained FREE and evaluated its performance on both the ovarian tumor (OT) (human OT cells) data set and zebrafish (ZF) (brain in mature female ZF) data set. Specifically, comparing the state-of-art method, FREE demonstrates higher performance in multiple evaluation metrics across both the OT and ZF data sets, with a particular emphasis on precision, and it demonstrates accurate predictions of a greater number of positive envelopes among the top-ranked envelopes based on their scores. Moreover, within a cross-species data set of ZF, FREE identified a higher number of proteoform-spectrum matches (PrSMs), increasing the count from 50,795 to 52,927 compared to EnvCNN, the amalgamation of FREE with TopFD also exhibits a commendable capacity to discern 117,883 fragment ions, thus surpassing the 97,554 fragment ions identified through the application of EnvCNN in conjunction with TopFD. To further validate the performance of FREE, we have tested 10 a cross-species top-down proteomes containing 36 subdata set from ProteomeXchange. The results reveal that, after deconvolution with TopFD + FREE, TopPIC identifies more PrSMs across these 10 data sets in both the first and second rounds of experiments. These findings underscore the robustness and generalization capabilities of the FREE approach in diverse proteomes.
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Affiliation(s)
- Jiancheng Zhong
- College of Information Science and Engineering, Hunan Normal University, ChangSha 410081, China
| | - Xingran Song
- College of Information Science and Engineering, Hunan Normal University, ChangSha 410081, China
| | - Shaokai Wang
- David R. Cheriton School of Computer Science, University of Waterloo, Waterloo N2L 3G1, Canada
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4
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Xu T, Wang Q, Wang Q, Sun L. Mass spectrometry-intensive top-down proteomics: an update on technology advancements and biomedical applications. ANALYTICAL METHODS : ADVANCING METHODS AND APPLICATIONS 2024; 16:4664-4682. [PMID: 38973469 PMCID: PMC11257149 DOI: 10.1039/d4ay00651h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2024] [Accepted: 06/25/2024] [Indexed: 07/09/2024]
Abstract
Proteoforms are all forms of protein molecules from the same gene because of variations at the DNA, RNA, and protein levels, e.g., alternative splicing and post-translational modifications (PTMs). Delineation of proteins in a proteoform-specific manner is crucial for understanding their biological functions. Mass spectrometry (MS)-intensive top-down proteomics (TDP) is promising for comprehensively characterizing intact proteoforms in complex biological systems. It has achieved substantial progress in technological development, including sample preparation, proteoform separations, MS instrumentation, and bioinformatics tools. In a single TDP study, thousands of proteoforms can be identified and quantified from a cell lysate. It has also been applied to various biomedical research to better our understanding of protein function in regulating cellular processes and to discover novel proteoform biomarkers of diseases for early diagnosis and therapeutic development. This review covers the most recent technological development and biomedical applications of MS-intensive TDP.
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Affiliation(s)
- Tian Xu
- Department of Chemistry, Michigan State University, 578 S Shaw Lane, East Lansing, MI 48824, USA.
| | - Qianjie Wang
- Department of Chemistry, Michigan State University, 578 S Shaw Lane, East Lansing, MI 48824, USA.
| | - Qianyi Wang
- Department of Chemistry, Michigan State University, 578 S Shaw Lane, East Lansing, MI 48824, USA.
| | - Liangliang Sun
- Department of Chemistry, Michigan State University, 578 S Shaw Lane, East Lansing, MI 48824, USA.
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5
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Fang F, Gao G, Wang Q, Wang Q, Sun L. Combining SDS-PAGE to capillary zone electrophoresis-tandem mass spectrometry for high-resolution top-down proteomics analysis of intact histone proteoforms. Proteomics 2024:e2300650. [PMID: 39018239 DOI: 10.1002/pmic.202300650] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2023] [Revised: 06/15/2024] [Accepted: 07/08/2024] [Indexed: 07/19/2024]
Abstract
Mass spectrometry (MS)-based top-down proteomics (TDP) analysis of histone proteoforms provides critical information about combinatorial post-translational modifications (PTMs), which is vital for pursuing a better understanding of epigenetic regulation of gene expression. It requires high-resolution separations of histone proteoforms before MS and tandem MS (MS/MS) analysis. In this work, for the first time, we combined SDS-PAGE-based protein fractionation (passively eluting proteins from polyacrylamide gels as intact species for mass spectrometry, PEPPI-MS) with capillary zone electrophoresis (CZE)-MS/MS for high-resolution characterization of histone proteoforms. We systematically studied the histone proteoform extraction from SDS-PAGE gel and follow-up cleanup as well as CZE-MS/MS, to determine an optimal procedure. The optimal procedure showed reproducible and high-resolution separation and characterization of histone proteoforms. SDS-PAGE separated histone proteins (H1, H2, H3, and H4) based on their molecular weight and CZE provided additional separations of proteoforms of each histone protein based on their electrophoretic mobility, which was affected by PTMs, for example, acetylation and phosphorylation. Using the technique, we identified over 200 histone proteoforms from a commercial calf thymus histone sample with good reproducibility. The orthogonal and high-resolution separations of SDS-PAGE and CZE made our technique attractive for the delineation of histone proteoforms extracted from complex biological systems.
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Affiliation(s)
- Fei Fang
- Department of Chemistry, Michigan State University, East Lansing, Michigan, USA
| | - Guangyao Gao
- Department of Chemistry, Michigan State University, East Lansing, Michigan, USA
| | - Qianyi Wang
- Department of Chemistry, Michigan State University, East Lansing, Michigan, USA
| | - Qianjie Wang
- Department of Chemistry, Michigan State University, East Lansing, Michigan, USA
| | - Liangliang Sun
- Department of Chemistry, Michigan State University, East Lansing, Michigan, USA
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6
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Fang F, Xu T, Hagar HTC, Hovde S, Kuo MH, Sun L. A pilot study for deciphering post-translational modifications and proteoforms of tau protein by capillary electrophoresis-mass spectrometry. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.04.602093. [PMID: 39026802 PMCID: PMC11257423 DOI: 10.1101/2024.07.04.602093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/20/2024]
Abstract
Abnormal accumulation of tau proteins is one pathological hallmark of Alzheimer□s disease (AD). Many tau protein post-translational modifications (PTMs) are associated with the development of AD, such as phosphorylation, acetylation, and methylation. Therefore, a complete picture of PTM landscape of tau is critical for understanding the molecular mechanisms of AD progression. Here, we offered a pilot study of combining two complementary analytical techniques, capillary zone electrophoresis (CZE)-tandem mass spectrometry (MS/MS) and reversed-phase liquid chromatography (RPLC)-MS/MS, for bottom-up proteomics of recombinant human tau-0N3R. We identified 53 phosphorylation sites of tau-0N3R in total, which is about 30% higher than that from RPLC-MS/MS alone. CZE-MS/MS provided more PTM sites (i.e., phosphorylation) and modified peptides of tau-0N3R than RPLC-MS/MS, and its predicted electrophoretic mobility helped improve the confidence of the identified modified peptides. We developed a highly efficient capillary isoelectric focusing (cIEF)-MS technique to offer a bird's-eye view of tau-0N3R proteoforms, with 11 putative tau-0N3R proteoforms carrying up to nine phosphorylation sites and lower pI values from more phosphorylated proteoforms detected. Interestingly, under a native-like cIEF-MS condition, we observed three putative tau-0N3R dimers carrying phosphate groups. The findings demonstrate that CE-MS is a valuable analytical technique for the characterization of tau PTMs, proteoforms, and even oligomerization.
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7
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Colón Rosado J, Sun L. Solid-Phase Microextraction-Aided Capillary Zone Electrophoresis-Mass Spectrometry: Toward Bottom-Up Proteomics of Single Human Cells. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2024; 35:1120-1127. [PMID: 38514245 PMCID: PMC11157658 DOI: 10.1021/jasms.3c00429] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Revised: 03/02/2024] [Accepted: 03/13/2024] [Indexed: 03/23/2024]
Abstract
Capillary zone electrophoresis-mass spectrometry (CZE-MS) has been recognized as a valuable technique for the proteomics of mass-limited biological samples (i.e., single cells). However, its broad adoption for single cell proteomics (SCP) of human cells has been impeded by the low sample loading capacity of CZE, only allowing us to use less than 5% of the available peptide material for each measurement. Here we present a reversed-phase-based solid-phase microextraction (RP-SPME)-CZE-MS platform to solve the issue, paving the way for SCP of human cells using CZE-MS. The RP-SPME-CZE system was constructed in one fused silica capillary with zero dead volume for connection via in situ synthesis of a frit, followed by packing C8 beads into the capillary to form a roughly 2 mm long SPME section. Peptides captured by SPME were eluted with a buffer containing 30% (v/v) acetonitrile and 50 mM ammonium acetate (pH 6.5), followed by dynamic pH junction-based CZE-MS. The SPME-CZE-MS enabled the injection of nearly 40% of the available peptide sample for each measurement. The system identified 257 ± 24 proteins and 523 ± 69 peptides (N = 2) using a Q-Exactive HF mass spectrometer when only 0.25 ng of a commercial HeLa cell digest was available in the sample vial and 0.1 ng of the sample was injected. The amount of available peptide is equivalent to the protein mass of one HeLa cell. The data indicate that SPME-CZE-MS is ready for SCP of human cells.
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Affiliation(s)
- Jorge
A. Colón Rosado
- Department of Chemistry, Michigan
State University, 578 S Shaw Lane, East Lansing, Michigan 48824, United States
| | - Liangliang Sun
- Department of Chemistry, Michigan
State University, 578 S Shaw Lane, East Lansing, Michigan 48824, United States
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8
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Štěpánová S, Kašička V. Determination of physicochemical parameters of (bio)molecules and (bio)particles by capillary electromigration methods. J Sep Sci 2024; 47:e2400174. [PMID: 38867483 DOI: 10.1002/jssc.202400174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2024] [Revised: 05/03/2024] [Accepted: 05/10/2024] [Indexed: 06/14/2024]
Abstract
The review provides an overview of recent developments and applications of capillary electromigration (CE) methods for the determination of important physicochemical parameters of various (bio)molecules and (bio)particles. These parameters include actual and limiting (absolute) ionic mobilities, effective electrophoretic mobilities, effective charges, isoelectric points, electrokinetic potentials, hydrodynamic radii, diffusion coefficients, relative molecular masses, acidity (ionization) constants, binding constants and stoichiometry of (bio)molecular complexes, changes of Gibbs free energy, enthalpy and entropy and rate constants of chemical reactions and interactions, retention factors and partition and distribution coefficients. For the determination of these parameters, the following CE methods are employed: zone electrophoresis in a free solution or in sieving media, isotachophoresis, isoelectric focusing, affinity electrophoresis, electrokinetic chromatography, and electrochromatography. In the individual sections, the procedures for the determination of the above parameters by the particular CE methods are described.
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Affiliation(s)
- Sille Štěpánová
- Electromigration methods, Institute of Organic Chemistry and Biochemistry, The Czech Academy of Sciences, Prague, Czech Republic
| | - Václav Kašička
- Electromigration methods, Institute of Organic Chemistry and Biochemistry, The Czech Academy of Sciences, Prague, Czech Republic
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9
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Sadeghi S, Chen W, Wang Q, Wang Q, Fang F, Liu X, Sun L. Pilot Evaluation of the Long-Term Reproducibility of Capillary Zone Electrophoresis-Tandem Mass Spectrometry for Top-Down Proteomics of a Complex Proteome Sample. J Proteome Res 2024; 23:1399-1407. [PMID: 38417052 PMCID: PMC11002928 DOI: 10.1021/acs.jproteome.3c00872] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Revised: 02/09/2024] [Accepted: 02/14/2024] [Indexed: 03/01/2024]
Abstract
Mass spectrometry (MS)-based top-down proteomics (TDP) has revolutionized biological research by measuring intact proteoforms in cells, tissues, and biofluids. Capillary zone electrophoresis-tandem MS (CZE-MS/MS) is a valuable technique for TDP, offering a high peak capacity and sensitivity for proteoform separation and detection. However, the long-term reproducibility of CZE-MS/MS in TDP remains unstudied, which is a crucial aspect for large-scale studies. This work investigated the long-term qualitative and quantitative reproducibility of CZE-MS/MS for TDP for the first time, focusing on a yeast cell lysate. Over 1000 proteoforms were identified per run across 62 runs using one linear polyacrylamide (LPA)-coated separation capillary, highlighting the robustness of the CZE-MS/MS technique. However, substantial decreases in proteoform intensity and identification were observed after some initial runs due to proteoform adsorption onto the capillary inner wall. To address this issue, we developed an efficient capillary cleanup procedure using diluted ammonium hydroxide, achieving high qualitative and quantitative reproducibility for the yeast sample across at least 23 runs. The data underscore the capability of CZE-MS/MS for large-scale quantitative TDP of complex samples, signaling its readiness for deployment in broad biological applications. The MS RAW files were deposited in ProteomeXchange Consortium with the data set identifier of PXD046651.
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Affiliation(s)
- Seyed
Amirhossein Sadeghi
- Department
of Chemistry, Michigan State University, 578 S Shaw Lane, East Lansing, Michigan 48824, United States
| | - Wenrong Chen
- Department
of BioHealth Informatics, Indiana University-Purdue
University Indianapolis, 535 W Michigan Street, Indianapolis, Indiana 46202, United States
| | - Qianyi Wang
- Department
of Chemistry, Michigan State University, 578 S Shaw Lane, East Lansing, Michigan 48824, United States
| | - Qianjie Wang
- Department
of Chemistry, Michigan State University, 578 S Shaw Lane, East Lansing, Michigan 48824, United States
| | - Fei Fang
- Department
of Chemistry, Michigan State University, 578 S Shaw Lane, East Lansing, Michigan 48824, United States
| | - Xiaowen Liu
- Deming
Department of Medicine, School of Medicine, Tulane University, 1441 Canal Street, New Orleans, Louisiana 70112, United States
| | - Liangliang Sun
- Department
of Chemistry, Michigan State University, 578 S Shaw Lane, East Lansing, Michigan 48824, United States
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10
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Wang Q, Fang F, Wang Q, Sun L. Capillary zone electrophoresis-high field asymmetric ion mobility spectrometry-tandem mass spectrometry for top-down characterization of histone proteoforms. Proteomics 2024; 24:e2200389. [PMID: 37963825 PMCID: PMC10922523 DOI: 10.1002/pmic.202200389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 08/14/2023] [Accepted: 10/31/2023] [Indexed: 11/16/2023]
Abstract
Characterization of histone proteoforms with various post-translational modifications (PTMs) is critical for a better understanding of functions of histone proteoforms in epigenetic control of gene expression. Mass spectrometry (MS)-based top-down proteomics (TDP) is a valuable approach for delineating histone proteoforms because it can provide us with a bird's-eye view of histone proteoforms carrying diverse combinations of PTMs. Here, we present the first example of coupling capillary zone electrophoresis (CZE), ion mobility spectrometry (IMS), and MS for online multi-dimensional separations of histone proteoforms. Our CZE-high-field asymmetric waveform IMS (FAIMS)-MS/MS platform identified 366 (ProSight PD) and 602 (TopPIC) histone proteoforms from a commercial calf histone sample using a low microgram amount of histone sample as the starting material. CZE-FAIMS-MS/MS improved the number of histone proteoform identifications by about 3 folds compared to CZE-MS/MS alone (without FAIMS). The results indicate that CZE-FAIMS-MS/MS could be a useful tool for comprehensive characterization of histone proteoforms with high sensitivity.
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Affiliation(s)
- Qianyi Wang
- Department of Chemistry, Michigan State University, East Lansing, Michigan, USA
| | - Fei Fang
- Department of Chemistry, Michigan State University, East Lansing, Michigan, USA
| | - Qianjie Wang
- Department of Chemistry, Michigan State University, East Lansing, Michigan, USA
| | - Liangliang Sun
- Department of Chemistry, Michigan State University, East Lansing, Michigan, USA
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11
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Kašička V. Recent developments in capillary and microchip electroseparations of peptides (2021-mid-2023). Electrophoresis 2024; 45:165-198. [PMID: 37670208 DOI: 10.1002/elps.202300152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2023] [Revised: 08/22/2023] [Accepted: 08/22/2023] [Indexed: 09/07/2023]
Abstract
This review article brings a comprehensive survey of developments and applications of high-performance capillary and microchip electromigration methods (zone electrophoresis in a free solution or in sieving media, isotachophoresis, isoelectric focusing, affinity electrophoresis, electrokinetic chromatography, and electrochromatography) for analysis, micropreparation, and physicochemical characterization of peptides in the period from 2021 up to ca. the middle of 2023. Progress in the study of electromigration properties of peptides and various aspects of their analysis, such as sample preparation, adsorption suppression, electroosmotic flow regulation, and detection, are presented. New developments in the particular capillary electromigration methods are demonstrated, and several types of their applications are reported. They cover qualitative and quantitative analysis of synthetic or isolated peptides and determination of peptides in complex biomatrices, peptide profiling of biofluids and tissues, and monitoring of chemical and enzymatic reactions and physicochemical changes of peptides. They include also amino acid and sequence analysis of peptides, peptide mapping of proteins, separation of stereoisomers of peptides, and their chiral analyses. In addition, micropreparative separations and physicochemical characterization of peptides and their interactions with other (bio)molecules by the above CE methods are described.
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Affiliation(s)
- Václav Kašička
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Prague, Czechia
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12
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Xu T, Wang Q, Wang Q, Sun L. Coupling High-Field Asymmetric Waveform Ion Mobility Spectrometry with Capillary Zone Electrophoresis-Tandem Mass Spectrometry for Top-Down Proteomics. Anal Chem 2023; 95:9497-9504. [PMID: 37254456 PMCID: PMC10540249 DOI: 10.1021/acs.analchem.3c00551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Capillary zone electrophoresis-tandem mass spectrometry (CZE-MS/MS) has emerged as an essential technique for top-down proteomics (TDP), providing superior separation efficiency and high detection sensitivity for proteoform analysis. Here, we aimed to further enhance the performance of CZE-MS/MS for TDP via coupling online gas-phase proteoform fractionation using high-field asymmetric waveform ion mobility spectrometry (FAIMS). When the compensation voltage (CV) of FAIMS was changed from -50 to 30 V, the median mass of identified proteoforms increased from less than 10 kDa to about 30 kDa, suggesting that FAIMS can efficiently fractionate proteoforms by their size. CZE-FAIMS-MS/MS boosted the number of proteoform identifications from a yeast sample by nearly 3-fold relative to CZE-MS/MS alone. It particularly benefited the identification of relatively large proteoforms, improving the number of proteoforms in a mass range of 20-45 kDa by 6-fold compared to CZE-MS/MS alone. FAIMS fractionation gained nearly 20-fold better signal-to-noise ratios of randomly selected proteoforms than no FAIMS. We expect that CZE-FAIMS-MS/MS will be a useful tool for further advancing the sensitivity and coverage of TDP. This work shows the first example of coupling CE with ion mobility spectrometry (IMS) for TDP.
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Affiliation(s)
- Tian Xu
- Department of Chemistry, Michigan State University, 578 S Shaw Lane, East Lansing, Michigan 48824, United States
| | - Qianjie Wang
- Department of Chemistry, Michigan State University, 578 S Shaw Lane, East Lansing, Michigan 48824, United States
| | - Qianyi Wang
- Department of Chemistry, Michigan State University, 578 S Shaw Lane, East Lansing, Michigan 48824, United States
| | - Liangliang Sun
- Department of Chemistry, Michigan State University, 578 S Shaw Lane, East Lansing, Michigan 48824, United States
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13
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Ryan KA, Bruening ML. Online protein digestion in membranes between capillary electrophoresis and mass spectrometry. Analyst 2023; 148:1611-1619. [PMID: 36912593 DOI: 10.1039/d3an00106g] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/10/2023]
Abstract
This research employs pepsin-containing membranes to digest proteins online after a capillary electrophoresis (CE) separation and prior to tandem mass spectrometry. Proteolysis after the separation allows the peptides from a given protein to enter the mass spectrometer in a single plug. Thus, migration time can serve as an additional criterion for confirming the identification of a peptide. The membrane resides in a sheath-flow electrospray ionization (ESI) source to enable digestion immediately before spray into the mass spectrometer, thus limiting separation of the digested peptides. Using the same membrane, digestion occurred reproducibly during 20 consecutive CE analyses performed over a 10 h period. Additionally, after separating a mixture of six unreduced proteins with CE, online digestion facilitated protein identification with at least 2 identifiable peptides for all the proteins. Sequence coverages were >75% for myoglobin and carbonic anhydrase II but much lower for proteins containing disulfide bonds. Development of methods for efficient separation of reduced proteins or identification of cross-linked peptides should enhance sequence coverages for proteins with disulfide bonds. Migration times for the peptides identified from a specific protein differed by <∼30 s, which allows for rejection of some spurious peptide identifications.
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Affiliation(s)
- Kendall A Ryan
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA.
| | - Merlin L Bruening
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA. .,Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, IN 46556, USA
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14
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Chen D, McCool EN, Yang Z, Shen X, Lubeckyj RA, Xu T, Wang Q, Sun L. Recent advances (2019-2021) of capillary electrophoresis-mass spectrometry for multilevel proteomics. MASS SPECTROMETRY REVIEWS 2023; 42:617-642. [PMID: 34128246 PMCID: PMC8671558 DOI: 10.1002/mas.21714] [Citation(s) in RCA: 30] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Revised: 05/29/2021] [Accepted: 06/03/2021] [Indexed: 05/06/2023]
Abstract
Multilevel proteomics aims to delineate proteins at the peptide (bottom-up proteomics), proteoform (top-down proteomics), and protein complex (native proteomics) levels. Capillary electrophoresis-mass spectrometry (CE-MS) can achieve highly efficient separation and highly sensitive detection of complex mixtures of peptides, proteoforms, and even protein complexes because of its substantial technical progress. CE-MS has become a valuable alternative to the routinely used liquid chromatography-mass spectrometry for multilevel proteomics. This review summarizes the most recent (2019-2021) advances of CE-MS for multilevel proteomics regarding technological progress and biological applications. We also provide brief perspectives on CE-MS for multilevel proteomics at the end, highlighting some future directions and potential challenges.
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Affiliation(s)
| | | | | | - Xiaojing Shen
- Department of Chemistry, Michigan State University, 578 S Shaw Lane, East Lansing, MI 48824, USA
| | - Rachele A. Lubeckyj
- Department of Chemistry, Michigan State University, 578 S Shaw Lane, East Lansing, MI 48824, USA
| | - Tian Xu
- Department of Chemistry, Michigan State University, 578 S Shaw Lane, East Lansing, MI 48824, USA
| | - Qianjie Wang
- Department of Chemistry, Michigan State University, 578 S Shaw Lane, East Lansing, MI 48824, USA
| | - Liangliang Sun
- Department of Chemistry, Michigan State University, 578 S Shaw Lane, East Lansing, MI 48824, USA
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15
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Wang Q, Sun L, Knut Lundquist P. Large-scale top-down proteomics of the Arabidopsis thaliana leaf and chloroplast proteomes. Proteomics 2023; 23:e2100377. [PMID: 36070201 PMCID: PMC9957804 DOI: 10.1002/pmic.202100377] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Revised: 08/16/2022] [Accepted: 08/23/2022] [Indexed: 11/11/2022]
Abstract
We present a large-scale top-down proteomics (TDP) study of plant leaf and chloroplast proteins, achieving the identification of over 4700 unique proteoforms. Using capillary zone electrophoresis coupled with tandem mass spectrometry analysis of offline size-exclusion chromatography fractions, we identify 3198 proteoforms for total leaf and 1836 proteoforms for chloroplast, with 1024 and 363 proteoforms having post-translational modifications, respectively. The electrophoretic mobility prediction of capillary zone electrophoresis allowed us to validate post-translational modifications that impact the charge state such as acetylation and phosphorylation. Identified modifications included Trp (di)oxidation events on six chloroplast proteins that may represent novel targets of singlet oxygen sensing. Furthermore, our TDP data provides direct experimental evidence of the N- and C-terminal residues of numerous mature proteoforms from chloroplast, mitochondria, endoplasmic reticulum, and other sub-cellular localizations. With this information, we suggest true transit peptide cleavage sites and correct sub-cellular localization signal predictions. This large-scale analysis illustrates the power of top-down proteoform identification of post-translational modifications and intact sequences that can benefit our understanding of both the structure and function of hundreds of plant proteins.
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Affiliation(s)
- Qianjie Wang
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, USA
- Plant Resilience Institute, Michigan State University, East Lansing, Michigan, USA
- Department of Chemistry, Michigan State University, East Lansing, Michigan, USA
| | - Liangliang Sun
- Department of Chemistry, Michigan State University, East Lansing, Michigan, USA
| | - Peter Knut Lundquist
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, USA
- Plant Resilience Institute, Michigan State University, East Lansing, Michigan, USA
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16
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Winkels K, Koudelka T, Kaulich PT, Leippe M, Tholey A. Validation of Top-Down Proteomics Data by Bottom-Up-Based N-Terminomics Reveals Pitfalls in Top-Down-Based Terminomics Workflows. J Proteome Res 2022; 21:2185-2196. [PMID: 35972260 DOI: 10.1021/acs.jproteome.2c00277] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Bottom-up proteomics (BUP)-based N-terminomics techniques have become standard to identify protein N-termini. While these methods rely on the identification of N-terminal peptides only, top-down proteomics (TDP) comes with the promise to provide additional information about post-translational modifications and the respective C-termini. To evaluate the potential of TDP for terminomics, two established TDP workflows were employed for the proteome analysis of the nematode Caenorhabditis elegans. The N-termini of the identified proteoforms were validated using a BUP-based N-terminomics approach. The TDP workflows used here identified 1658 proteoforms, the N-termini of which were verified by BUP in 25% of entities only. Caveats in both the BUP- and TDP-based workflows were shown to contribute to this low overlap. In BUP, the use of trypsin prohibits the detection of arginine-rich or arginine-deficient N-termini, while in TDP, the formation of artificially generated termini was observed in particular in a workflow encompassing sample treatment with high acid concentrations. Furthermore, we demonstrate the applicability of reductive dimethylation in TDP to confirm biological N-termini. Overall, our study shows not only the potential but also current limitations of TDP for terminomics studies and also presents suggestions for future developments, for example, for data quality control, allowing improvement of the detection of protein termini by TDP.
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Affiliation(s)
- Konrad Winkels
- Systematic Proteome Research & Bioanalytics, Institute for Experimental Medicine, Christian-Albrechts-Universität zu Kiel, 24105 Kiel, Germany
| | - Tomas Koudelka
- Systematic Proteome Research & Bioanalytics, Institute for Experimental Medicine, Christian-Albrechts-Universität zu Kiel, 24105 Kiel, Germany
| | - Philipp T Kaulich
- Systematic Proteome Research & Bioanalytics, Institute for Experimental Medicine, Christian-Albrechts-Universität zu Kiel, 24105 Kiel, Germany
| | - Matthias Leippe
- Comparative Immunobiology, Zoological Institute, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
| | - Andreas Tholey
- Systematic Proteome Research & Bioanalytics, Institute for Experimental Medicine, Christian-Albrechts-Universität zu Kiel, 24105 Kiel, Germany
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17
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Chen W, McCool EN, Sun L, Zang Y, Ning X, Liu X. Evaluation of Machine Learning Models for Proteoform Retention and Migration Time Prediction in Top-Down Mass Spectrometry. J Proteome Res 2022; 21:1736-1747. [PMID: 35616364 PMCID: PMC9250612 DOI: 10.1021/acs.jproteome.2c00124] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
Reversed-phase liquid
chromatography (RPLC) and capillary zone
electrophoresis (CZE) are two primary proteoform separation methods
in mass spectrometry (MS)-based top-down proteomics. Proteoform retention
time (RT) prediction in RPLC and migration time (MT) prediction in
CZE provide additional information for accurate proteoform identification
and quantification. While existing methods are mainly focused on peptide
RT and MT prediction in bottom-up MS, there is still a lack of methods
for proteoform RT and MT prediction in top-down MS. We systematically
evaluated eight machine learning models and a transfer learning method
for proteoform RT prediction and five models and the transfer learning
method for proteoform MT prediction. Experimental results showed that
a gated recurrent unit (GRU)-based model with transfer learning achieved
a high accuracy (R = 0.978) for proteoform RT prediction
and that the GRU-based model and a fully connected neural network
model obtained a high accuracy of R = 0.982 and 0.981
for proteoform MT prediction, respectively.
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Affiliation(s)
- Wenrong Chen
- Department of BioHealth Informatics, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana 46202, United Staes
| | - Elijah N McCool
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, United Staes
| | - Liangliang Sun
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, United Staes
| | - Yong Zang
- Department of Biostatics and Health Data Sciences, Indiana University School of Medicine, Indianapolis, Indiana 46202, United Staes
| | - Xia Ning
- Department of Biomedical Informatics, The Ohio State University, Columbus, Ohio 43210, United Staes.,Department of Computer Science and Engineering, The Ohio State University, Columbus, Ohio 43210, United Staes.,Translational Data Analytics Institute, The Ohio State University, Columbus, Ohio 43210, United Staes
| | - Xiaowen Liu
- Tulane Center for Biomedical Informatics and Genomics, Tulane University, New Orleans, Louisiana 70112, United Staes.,Deming Department of Medicine, Tulane University, New Orleans, Louisiana 70112, United Staes
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18
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Johnson KR, Greguš M, Kostas JC, Ivanov AR. Capillary Electrophoresis Coupled to Electrospray Ionization Tandem Mass Spectrometry for Ultra-Sensitive Proteomic Analysis of Limited Samples. Anal Chem 2022; 94:704-713. [PMID: 34983182 PMCID: PMC8770592 DOI: 10.1021/acs.analchem.1c02929] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this work, we developed an ultra-sensitive CE-MS/MS method for bottom-up proteomics analysis of limited samples, down to sub-nanogram levels of total protein. Analysis of 880 and 88 pg of the HeLa protein digest standard by CE-MS/MS yielded ∼1100 ± 46 and ∼160 ± 59 proteins, respectively, demonstrating higher protein and peptide identifications than the current state-of-the-art CE-MS/MS-based proteomic analyses with similar amounts of sample. To demonstrate potential applications of our ultra-sensitive CE-MS/MS method for the analysis of limited biological samples, we digested 500 and 1000 HeLa cells using a miniaturized in-solution digestion workflow. From 1-, 5-, and 10-cell equivalents injected from the resulted digests, we identified 744 ± 127, 1139 ± 24, and 1271 ± 6 proteins and 3353 ± 719, 5709 ± 513, and 8527 ± 114 peptide groups, respectively. Furthermore, we performed a comparative assessment of CE-MS/MS and two reversed-phased nano-liquid chromatography (RP-nLC-MS/MS) methods (monolithic and packed columns) for the analysis of a ∼10 ng HeLa protein digest standard. Our results demonstrate complementarity in the protein- and especially peptide-level identifications of the evaluated CE-MS- and RP-nLC-MS-based methods. The techniques were further assessed to detect post-translational modifications and highlight the strengths of the CE-MS/MS approach in identifying potentially important and biologically relevant modified peptides. With a migration window of ∼60 min, CE-MS/MS identified ∼2000 ± 53 proteins on average from a single injection of ∼8.8 ng of the HeLa protein digest standard. Additionally, an average of 232 ± 10 phosphopeptides and 377 ± 14 N-terminal acetylated peptides were identified in CE-MS/MS analyses at this sample amount, corresponding to 2- and 1.5-fold more identifications for each respective modification found by nLC-MS/MS methods.
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Affiliation(s)
- Kendall R Johnson
- Department of Chemistry and Chemical Biology, Northeastern University, Barnett Institute of Chemical and Biological Analysis, 360 Huntington Avenue, Boston, Massachusetts 02115, United States
| | - Michal Greguš
- Department of Chemistry and Chemical Biology, Northeastern University, Barnett Institute of Chemical and Biological Analysis, 360 Huntington Avenue, Boston, Massachusetts 02115, United States
| | - James C Kostas
- Department of Chemistry and Chemical Biology, Northeastern University, Barnett Institute of Chemical and Biological Analysis, 360 Huntington Avenue, Boston, Massachusetts 02115, United States
| | - Alexander R Ivanov
- Department of Chemistry and Chemical Biology, Northeastern University, Barnett Institute of Chemical and Biological Analysis, 360 Huntington Avenue, Boston, Massachusetts 02115, United States
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19
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Kozlowski LP. Proteome-pI 2.0: proteome isoelectric point database update. Nucleic Acids Res 2022; 50:D1535-D1540. [PMID: 34718696 PMCID: PMC8728302 DOI: 10.1093/nar/gkab944] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2021] [Revised: 09/28/2021] [Accepted: 10/04/2021] [Indexed: 11/18/2022] Open
Abstract
Proteome-pI 2.0 is an update of an online database containing predicted isoelectric points and pKa dissociation constants of proteins and peptides. The isoelectric point-the pH at which a particular molecule carries no net electrical charge-is an important parameter for many analytical biochemistry and proteomics techniques. Additionally, it can be obtained directly from the pKa values of individual charged residues of the protein. The Proteome-pI 2.0 database includes data for over 61 million protein sequences from 20 115 proteomes (three to four times more than the previous release). The isoelectric point for proteins is predicted by 21 methods, whereas pKa values are inferred by one method. To facilitate bottom-up proteomics analysis, individual proteomes were digested in silico with the five most commonly used proteases (trypsin, chymotrypsin, trypsin + LysC, LysN, ArgC), and the peptides' isoelectric point and molecular weights were calculated. The database enables the retrieval of virtual 2D-PAGE plots and customized fractions of a proteome based on the isoelectric point and molecular weight. In addition, isoelectric points for proteins in NCBI non-redundant (nr), UniProt, SwissProt, and Protein Data Bank are available in both CSV and FASTA formats. The database can be accessed at http://isoelectricpointdb2.org.
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Affiliation(s)
- Lukasz Pawel Kozlowski
- Institute of Informatics, Faculty of Mathematics, Informatics, and Mechanics, University of Warsaw, Warsaw, Mazovian Voivodeship 02-097, Poland
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20
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Kašička V. Recent developments in capillary and microchip electroseparations of peptides (2019-mid 2021). Electrophoresis 2021; 43:82-108. [PMID: 34632606 DOI: 10.1002/elps.202100243] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 09/29/2021] [Accepted: 09/30/2021] [Indexed: 12/19/2022]
Abstract
The review provides a comprehensive overview of developments and applications of high performance capillary and microchip electroseparation methods (zone electrophoresis, isotachophoresis, isoelectric focusing, affinity electrophoresis, electrokinetic chromatography, and electrochromatography) for analysis, microscale isolation, and physicochemical characterization of peptides from 2019 up to approximately the middle of 2021. Advances in the investigation of electromigration properties of peptides and in the methodology of their analysis, such as sample preparation, sorption suppression, EOF control, and detection, are presented. New developments in the individual CE and CEC methods are demonstrated and several types of their applications are shown. They include qualitative and quantitative analysis, determination in complex biomatrices, monitoring of chemical and enzymatic reactions and physicochemical changes, amino acid, sequence, and chiral analyses, and peptide mapping of proteins. In addition, micropreparative separations and determination of significant physicochemical parameters of peptides by CE and CEC methods are described.
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Affiliation(s)
- Václav Kašička
- Institute of Organic Chemistry and Biochemistry, The Czech Academy of Sciences, Prague 6, Czechia
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21
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Shen X, Xu T, Hakkila B, Hare M, Wang Q, Wang Q, Beckman JS, Sun L. Capillary Zone Electrophoresis-Electron-Capture Collision-Induced Dissociation on a Quadrupole Time-of-Flight Mass Spectrometer for Top-Down Characterization of Intact Proteins. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2021; 32:1361-1369. [PMID: 33749270 PMCID: PMC8576897 DOI: 10.1021/jasms.0c00484] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Mass spectrometry (MS)-based denaturing top-down proteomics (dTDP) requires high-capacity separation and extensive gas-phase fragmentation of proteoforms. Herein, we coupled capillary zone electrophoresis (CZE) to electron-capture collision-induced dissociation (ECciD) on an Agilent 6545 XT quadrupole time-of-flight (Q-TOF) mass spectrometer for dTDP for the first time. During ECciD, the protein ions were first fragmented using ECD, followed by further activation and fragmentation by applying a CID potential. In this pilot study, we optimized the CZE-ECciD method for small proteins (lower than 20 kDa) regarding the charge state of protein parent ions for fragmentation and the CID potential applied to maximize the protein backbone cleavage coverage and the number of sequence-informative fragment ions. The CZE-ECciD Q-TOF platform provided extensive backbone cleavage coverage for three standard proteins lower than 20 kDa from only single charge states in a single CZE-MS/MS run in the targeted MS/MS mode, including ubiquitin (97%, +7, 8.6 kDa), superoxide dismutase (SOD, 87%, +17, 16 kDa), and myoglobin (90%, +16, 17 kDa). The CZE-ECciD method produced comparable cleavage coverage of small proteins (i.e., myoglobin) with direct-infusion MS studies using electron transfer dissociation (ETD), activated ion-ETD, and combinations of ETD and collision-based fragmentation on high-end orbitrap mass spectrometers. The results render CZE-ECciD a new tool for dTDP to enhance both separation and gas-phase fragmentation of proteoforms.
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Affiliation(s)
- Xiaojing Shen
- Department of Chemistry, Michigan State University, 578 S Shaw Lane, East Lansing, Michigan 48824, United States
| | - Tian Xu
- Department of Chemistry, Michigan State University, 578 S Shaw Lane, East Lansing, Michigan 48824, United States
| | - Blake Hakkila
- e-MSion, Inc., 2121 NE Jack London Drive, Corvallis, Oregon 97330, United States
| | - Mike Hare
- e-MSion, Inc., 2121 NE Jack London Drive, Corvallis, Oregon 97330, United States
| | - Qianjie Wang
- Department of Chemistry, Michigan State University, 578 S Shaw Lane, East Lansing, Michigan 48824, United States
| | - Qianyi Wang
- Department of Chemistry, Michigan State University, 578 S Shaw Lane, East Lansing, Michigan 48824, United States
| | - Joseph S Beckman
- e-MSion, Inc., 2121 NE Jack London Drive, Corvallis, Oregon 97330, United States
- Linus Pauling Institute and the Department of Biochemistry and Biophysics, Oregon State University, Corvallis, Oregon 97331, United States
| | - Liangliang Sun
- Department of Chemistry, Michigan State University, 578 S Shaw Lane, East Lansing, Michigan 48824, United States
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22
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Chen D, Yang Z, Shen X, Sun L. Capillary Zone Electrophoresis-Tandem Mass Spectrometry As an Alternative to Liquid Chromatography-Tandem Mass Spectrometry for Top-down Proteomics of Histones. Anal Chem 2021; 93:4417-4424. [PMID: 33650845 PMCID: PMC8564867 DOI: 10.1021/acs.analchem.0c04237] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Top-down proteomics (TDP) is an ideal approach for deciphering the histone code and it routinely employs reversed-phase liquid chromatography (RPLC)-tandem mass spectrometry (MS/MS). Because of the extreme complexity of histones regarding the number of proteoforms, new analytical tools with high-capacity separation and highly sensitive detection of proteoforms are required for TDP of histones. Here we present capillary zone electrophoresis (CZE)-MS/MS via the electro-kinetically pumped sheath-flow CE-MS interface for large-scale top-down delineation of histone proteoforms. CZE-MS/MS identified a comparable number of proteoforms to RPLC-MS/MS from a calf histone sample with more than 30-fold less sample consumption (75-ng vs. Three μg), indicating its substantially higher sensitivity. We identified about 400 histone proteoforms from the calf histone sample using two-dimensional size-exclusion chromatography (SEC)-CZE-MS/MS with less than 300-ng proteins consumed. We identified histone proteoforms carrying various tentative post-translational modifications (PTMs), for example, acetylation, methylation (mono-, di-, and tri-), phosphorylation, and succinylation. The electrophoretic mobility (μef) of unmodified histone proteoforms can be predicted accurately (R2 = 0.98) with an optimized semiempirical model based on our recent work. The results render CZE-MS/MS as a useful tool for deciphering the histone code in a proteoform-specific manner and on a global scale.
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Affiliation(s)
- Daoyang Chen
- Department of Chemistry, Michigan State University, 578 S Shaw Ln, East Lansing, Michigan 48824, United States
| | - Zhichang Yang
- Department of Chemistry, Michigan State University, 578 S Shaw Ln, East Lansing, Michigan 48824, United States
| | - Xiaojing Shen
- Department of Chemistry, Michigan State University, 578 S Shaw Ln, East Lansing, Michigan 48824, United States
| | - Liangliang Sun
- Department of Chemistry, Michigan State University, 578 S Shaw Ln, East Lansing, Michigan 48824, United States
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23
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Miller RM, Ibrahim K, Smith LM. ProteaseGuru: A Tool for Protease Selection in Bottom-Up Proteomics. J Proteome Res 2021; 20:1936-1942. [PMID: 33661641 DOI: 10.1021/acs.jproteome.0c00954] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Bottom-up proteomics is currently the dominant strategy for proteome analysis. It relies critically upon the use of a protease to digest proteins into peptides, which are then identified by liquid chromatography-mass spectrometry (LC-MS). The choice of protease(s) has a substantial impact upon the utility of the bottom-up results obtained. Protease selection determines the nature of the peptides produced, which in turn affects the ability to infer the presence and quantities of the parent proteins and post-translational modifications in the sample. We present here the software tool ProteaseGuru, which provides in silico digestions by candidate proteases, allowing evaluation of their utility for bottom-up proteomic experiments. This information is useful for both studies focused on a single or small number of proteins, and for analysis of entire complex proteomes. ProteaseGuru provides a convenient user interface, valuable peptide information, and data visualizations enabling the comparison of digestion results of different proteases. The information provided includes data tables of theoretical peptide sequences and their biophysical properties, results summaries outlining the numbers of shared and unique peptides per protease, histograms facilitating the comparison of proteome-wide proteolytic data, protein-specific summaries, and sequence coverage maps. Examples are provided of its use to inform analysis of variant-containing proteins in the human proteome, as well as for studies requiring the use of multiple proteomic databases such as a human:mouse xenograft model, and microbiome metaproteomics.
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Affiliation(s)
- Rachel M Miller
- Department of Chemistry, University of Wisconsin, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Khairina Ibrahim
- Department of Chemistry, University of Wisconsin, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Lloyd M Smith
- Department of Chemistry, University of Wisconsin, 1101 University Avenue, Madison, Wisconsin 53706, United States
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24
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Stolz A, Hedeland Y, Salzer L, Römer J, Heiene R, Leclercq L, Cottet H, Bergquist J, Neusüß C. Capillary Zone Electrophoresis-Top-Down Tandem Mass Spectrometry for In-Depth Characterization of Hemoglobin Proteoforms in Clinical and Veterinary Samples. Anal Chem 2020; 92:10531-10539. [PMID: 32628011 DOI: 10.1021/acs.analchem.0c01350] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Hemoglobin (Hb) constitutes an important protein in clinical diagnostics-both in humans and animals. Among the high number of sequence variants, some can cause severe diseases. Moreover, chemical modifications such as glycation and carbamylation serve as important biomarkers for conditions such as diabetes and kidney diseases. In clinical routine analysis of glycated Hb, sequence variants or other Hb proteoforms can cause interference, resulting in wrong quantification results. We present a versatile and flexible capillary zone electrophoresis-mass spectrometry screening method for Hb proteoforms including sequence variants and modified species extracted from dried blood spot (DBS) samples with virtually no sample preparation. High separation power was achieved by application of a 5-layers successive multiple ionic polymer layers-coated capillary, enabling separation of positional isomers of glycated α- and β-chains on the intact level. Quantification of glycated Hb was in good correlation with the results obtained in a clinical routine method. Identification and characterization of known and unknown proteoforms was performed by fragmentation of intact precursor ions. N-Terminal and lysine glycation could be identified on the α- and β-chain, respectively. The versatility of the method was demonstrated by application to dog and cat DBS samples. We discovered a putative new sequence variant of the β-chain in dog (T38 → A). The presented method enables separation, characterization, and quantification of intact proteoforms, including positional isomers of glycated species in a single run. Combined with the simple sample preparation, our method represents a valuable tool to be used for deeper characterization of clinical and veterinary samples.
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Affiliation(s)
- Alexander Stolz
- Department of Chemistry, Aalen University, Beethovenstraße 1, 73430 Aalen, Germany.,Department of Pharmaceutical and Medicinal Chemistry, Friedrich Schiller University Jena, 07743 Jena, Germany
| | - Ylva Hedeland
- Department of Medical Sciences, Clinical Chemistry, , Uppsala University Hospital, SE-751 24 Uppsala, Sweden
| | - Liesa Salzer
- Department of Chemistry, Aalen University, Beethovenstraße 1, 73430 Aalen, Germany
| | - Jennifer Römer
- Department of Chemistry, Aalen University, Beethovenstraße 1, 73430 Aalen, Germany.,Institute of Analytical Chemistry, Chemo-and Biosensors,University of Regensburg, 93053 Regensburg, Germany
| | | | - Laurent Leclercq
- IBMM, University of Montpellier, CNRS, ENSCM, Beethovenstraße 1, 34090 Montpellier, France
| | - Hervé Cottet
- IBMM, University of Montpellier, CNRS, ENSCM, Beethovenstraße 1, 34090 Montpellier, France
| | - Jonas Bergquist
- Department of Chemistry -Biomedical Center, Analytical Chemistry, Uppsala University, SE-751 24 Uppsala, Sweden
| | - Christian Neusüß
- Department of Chemistry, Aalen University, Beethovenstraße 1, 73430 Aalen, Germany
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25
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Yang Z, Shen X, Chen D, Sun L. Toward a Universal Sample Preparation Method for Denaturing Top-Down Proteomics of Complex Proteomes. J Proteome Res 2020; 19:3315-3325. [PMID: 32419461 DOI: 10.1021/acs.jproteome.0c00226] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
A universal and standardized sample preparation method becomes vital for denaturing top-down proteomics (dTDP) to advance the scale and accuracy of proteoform delineation in complex biological systems. It needs to have high protein recovery, minimum bias, good reproducibility, and compatibility with downstream mass spectrometry (MS) analysis. Here, we employed a lysis buffer containing sodium dodecyl sulfate for extracting proteoforms from cells and, for the first time, compared membrane ultrafiltration (MU), chloroform-methanol precipitation (CMP), and single-spot solid-phase sample preparation using magnetic beads (SP3) for proteoform cleanup for dTDP. The MU method outperformed CMP and SP3 methods, resulting in high and reproducible protein recovery from both Escherichia coli cell (59 ± 3%) and human HepG2 cell (86 ± 5%) samples without a significant bias. Single-shot capillary zone electrophoresis (CZE)-MS/MS analyses of the prepared E. coli and HepG2 cell samples using the MU method identified 821 and 516 proteoforms, respectively. Nearly 30 and 50% of the identified E. coli and HepG2 proteins are membrane proteins. CZE-MS/MS identified 94 histone proteoforms from the HepG2 sample with various post-translational modifications, including acetylation, methylation, and phosphorylation. Our results suggest that combining the SDS-based protein extraction and the MU-based protein cleanup could be a universal sample preparation method for dTDP. The MS raw data have been deposited to the ProteomeXchange Consortium with the data set identifier PXD018248.
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Affiliation(s)
- Zhichang Yang
- Department of Chemistry, Michigan State University, 578 S Shaw Ln, East Lansing, Michigan 48824 United States
| | - Xiaojing Shen
- Department of Chemistry, Michigan State University, 578 S Shaw Ln, East Lansing, Michigan 48824 United States
| | - Daoyang Chen
- Department of Chemistry, Michigan State University, 578 S Shaw Ln, East Lansing, Michigan 48824 United States
| | - Liangliang Sun
- Department of Chemistry, Michigan State University, 578 S Shaw Ln, East Lansing, Michigan 48824 United States
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