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Václavek T, Foret F. Microfluidic device integrating single-cell extraction and electrical lysis for mass spectrometry detection of intracellular compounds. Electrophoresis 2023; 44:313-322. [PMID: 35315940 DOI: 10.1002/elps.202100379] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 01/26/2022] [Accepted: 01/28/2022] [Indexed: 02/01/2023]
Abstract
Analysis of cellular composition and metabolism at a single-cell resolution allows gaining more information about complex relationships of cells within tissues or whole living organisms by resolving the variance stemming from the cellular heterogeneity. Mass spectrometry (MS) is a perfect analytical tool satisfying the demanding requirements of detecting and identifying compounds present in such ultralow-volume samples of high chemical complexity. However, the method of sampling and sample ionization is crucial in obtaining relevant information. In this work, we present a microfluidic sampling platform that integrates single-cell extraction from MS-incompatible media with electrical cell lysis and nanoESI-MS analysis of human erythrocytes. Hemoglobin alpha and beta chains (300 amol/cell) were successfully identified in mass spectra of single-erythrocyte lysates.
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Affiliation(s)
- Tomáš Václavek
- Department of Bioanalytical Instrumentation, Institute of Analytical Chemistry of the CAS, Brno, Czech Republic.,Department of Biochemistry, Masaryk University, Brno, Czech Republic
| | - František Foret
- Department of Bioanalytical Instrumentation, Institute of Analytical Chemistry of the CAS, Brno, Czech Republic
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2
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Andring J, Combs J, McKenna R. Aspirin: A Suicide Inhibitor of Carbonic Anhydrase II. Biomolecules 2020; 10:biom10040527. [PMID: 32244293 PMCID: PMC7226357 DOI: 10.3390/biom10040527] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2020] [Revised: 03/25/2020] [Accepted: 03/30/2020] [Indexed: 12/31/2022] Open
Abstract
Carbonic anhydrase II (CAII) is a metalloenzyme that catalyzes the reversible hydration/dehydration of CO2/HCO3−. In addition, CAII is attributed to other catalytic reactions, including esterase activity. Aspirin (acetyl-salicylic acid), an everyday over-the-counter drug, has both ester and carboxylic acid moieties. Recently, compounds with a carboxylic acid group have been shown to inhibit CAII. Hence, we hypothesized that Aspirin could act as a substrate for esterase activity, and the product salicylic acid (SA), an inhibitor of CAII. Here, we present the crystal structure of CAII in complex with SA, a product of CAII crystals pre-soaked with Aspirin, to 1.35Å resolution. In addition, we provide kinetic data to support the observation that CAII converts Aspirin to its deacetylated form, SA. This data may also explain the short half-life of Aspirin, with CAII so abundant in blood, and that Aspirin could act as a suicide inhibitor of CAII.
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Andring JT, Kim CU, McKenna R. Structure and mechanism of copper-carbonic anhydrase II: a nitrite reductase. IUCRJ 2020; 7:287-293. [PMID: 32148856 PMCID: PMC7055381 DOI: 10.1107/s2052252520000986] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Accepted: 01/24/2020] [Indexed: 05/06/2023]
Abstract
Nitric oxide (NO) promotes vasodilation through the activation of guanylate cyclase, resulting in the relaxation of the smooth muscle vasculature and a subsequent decrease in blood pressure. Therefore, its regulation is of interest for the treatment and prevention of heart disease. An example is pulmonary hypertension which is treated by targeting this NO/vasodilation pathway. In bacteria, plants and fungi, nitrite (NO2 -) is utilized as a source of NO through enzymes known as nitrite reductases. These enzymes reduce NO2 - to NO through a catalytic metal ion, often copper. Recently, several studies have shown nitrite reductase activity of mammalian carbonic anhydrase II (CAII), yet the molecular basis for this activity is unknown. Here we report the crystal structure of copper-bound human CAII (Cu-CAII) in complex with NO2 - at 1.2 Å resolution. The structure exhibits Type 1 (T-1) and 2 (T-2) copper centers, analogous to bacterial nitrite reductases, both required for catalysis. The copper-substituted CAII active site is penta-coordinated with a 'side-on' bound NO2 -, resembling a T-2 center. At the N terminus, several residues that are normally disordered form a porphyrin ring-like configuration surrounding a second copper, acting as a T-1 center. A structural comparison with both apo- (without metal) and zinc-bound CAII (Zn-CAII) provides a mechanistic picture of how, in the presence of copper, CAII, with minimal conformational changes, can function as a nitrite reductase.
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Affiliation(s)
- Jacob T. Andring
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL 32610 USA
| | - Chae Un Kim
- Department of Physics, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - Robert McKenna
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL 32610 USA
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4
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Choi SB, Lombard-Banek C, Muñoz-LLancao P, Manzini MC, Nemes P. Enhanced Peptide Detection Toward Single-Neuron Proteomics by Reversed-Phase Fractionation Capillary Electrophoresis Mass Spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2018; 29:913-922. [PMID: 29147852 DOI: 10.1007/s13361-017-1838-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Revised: 10/12/2017] [Accepted: 10/14/2017] [Indexed: 06/07/2023]
Abstract
The ability to detect peptides and proteins in single cells is vital for understanding cell heterogeneity in the nervous system. Capillary electrophoresis (CE) nanoelectrospray ionization (nanoESI) provides high-resolution mass spectrometry (HRMS) with trace-level sensitivity, but compressed separation during CE challenges protein identification by tandem HRMS with limited MS/MS duty cycle. Here, we supplemented ultrasensitive CE-nanoESI-HRMS with reversed-phase (RP) fractionation to enhance identifications from protein digest amounts that approximate to a few mammalian neurons. An ~1 to 20 μg neuronal protein digest was fractionated on a RP column (ZipTip), and 1 ng to 500 pg of peptides were analyzed by a custom-built CE-HRMS system. Compared with the control (no fractionation), RP fractionation improved CE separation (theoretical plates ~274,000 versus 412,000 maximum, resp.), which enhanced detection sensitivity (2.5-fold higher signal-to-noise ratio), minimized co-isolation spectral interferences during MS/MS, and increased the temporal rate of peptide identification by up to ~57%. From 1 ng of protein digest (<5 neurons), CE with RP fractionation identified 737 protein groups (1,753 peptides), or ~480 protein groups (~1,650 peptides) on average per analysis. The approach was scalable to 500 pg of protein digest (~a single neuron), identifying 225 protein groups (623 peptides) in technical triplicates, or 141 protein groups on average per analysis. Among identified proteins, 101 proteins were products of genes that are known to be transcriptionally active in single neurons during early development of the brain, including those involved in synaptic transmission and plasticity and cytoskeletal organization. Graphical abstract ᅟ.
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Affiliation(s)
- Sam B Choi
- Department of Chemistry, The George Washington University, Washington, DC, 20052, USA
| | - Camille Lombard-Banek
- Department of Chemistry, The George Washington University, Washington, DC, 20052, USA
| | - Pablo Muñoz-LLancao
- Institute for Neuroscience, Department of Pharmacology and Physiology, The George Washington University, Washington, DC, 20052, USA
| | - M Chiara Manzini
- Institute for Neuroscience, Department of Pharmacology and Physiology, The George Washington University, Washington, DC, 20052, USA
| | - Peter Nemes
- Department of Chemistry, The George Washington University, Washington, DC, 20052, USA.
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD, 20742, USA.
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Connor DE, Chaitanya GV, Chittiboina P, McCarthy P, Scott LK, Schrott L, Minagar A, Nanda A, Alexander JS. Variations in the cerebrospinal fluid proteome following traumatic brain injury and subarachnoid hemorrhage. PATHOPHYSIOLOGY : THE OFFICIAL JOURNAL OF THE INTERNATIONAL SOCIETY FOR PATHOPHYSIOLOGY 2017; 24:169-183. [PMID: 28549769 PMCID: PMC7303909 DOI: 10.1016/j.pathophys.2017.04.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Revised: 04/06/2017] [Accepted: 04/28/2017] [Indexed: 12/19/2022]
Abstract
BACKGROUND Proteomic analysis of cerebrospinal fluid (CSF) has shown great promise in identifying potential markers of injury in neurodegenerative diseases [1-13]. Here we compared CSF proteomes in healthy individuals, with patients diagnosed with traumatic brain injury (TBI) and subarachnoid hemorrhage (SAH) in order to characterize molecular biomarkers which might identify these different clinical states and describe different molecular mechanisms active in each disease state. METHODS Patients presenting to the Neurosurgery service at the Louisiana State University Hospital-Shreveport with an admitting diagnosis of TBI or SAH were prospectively enrolled. Patients undergoing CSF sampling for diagnostic procedures were also enrolled as controls. CSF aliquots were subjected to 2-dimensional gel electrophoresis (2D GE) and spot percentage densities analyzed. Increased or decreased spot expression (compared to controls) was defined in terms of in spot percentages, with spots showing consistent expression change across TBI or SAH specimens being followed up by Matrix-Assisted Laser Desorption/Ionization mass spectrometry (MALDI-MS). Polypeptide masses generated were matched to known standards using a search of the NCBI and/or GenPept databases for protein matches. Eight hundred fifteen separately identifiable polypeptide migration spots were identified on 2D GE gels. MALDI-MS successfully identified 13 of 22 selected 2D GE spots as recognizable polypeptides. RESULTS Statistically significant changes were noted in the expression of fibrinogen, carbonic anhydrase-I (CA-I), peroxiredoxin-2 (Prx-2), both α and β chains of hemoglobin, serotransferrin (Tf) and N-terminal haptoglobin (Hp) in TBI and SAH specimens, as compared to controls. The greatest mean fold change among all specimens was seen in CA-I and Hp at 30.7 and -25.7, respectively. TBI specimens trended toward greater mean increases in CA-I and Prx-2 and greater mean decreases in Hp and Tf. CONCLUSIONS Consistent CSF elevation of CA-I and Prx-2 with concurrent depletion of Hp and Tf may represent a useful combination of biomarkers for the prediction of severity and prognosis following brain injury.
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Affiliation(s)
- David E Connor
- Baptist Health Neurosurgery Arkansas, Little Rock, AR, United States.
| | - Ganta V Chaitanya
- Cardiovascular Research Center, University of Virginia, Charlottesville, VA, United States.
| | - Prashant Chittiboina
- Surgical Neurology Branch, National Institute of Neurological Diseases and Stroke, Bethesda, MD, United States.
| | - Paul McCarthy
- Department of Medicine, Sect. of Nephrology, University of Maryland, Baltimore, MD, United States.
| | - L Keith Scott
- Department of Critical Care Medicine, Louisiana State University Health Sciences Center-Shreveport, LA, United States.
| | - Lisa Schrott
- Department of Pharmacology, Toxicology and Neuroscience, Louisiana State University Health Sciences Center-Shreveport, LA, United States.
| | - Alireza Minagar
- Department of Neurology, Louisiana State University Health Sciences Center-Shreveport, LA, United States.
| | - Anil Nanda
- Department of Neurosurgery, Louisiana State University Health Sciences Center-Shreveport, LA, United States.
| | - J Steven Alexander
- Department of Molecular and Cellular Physiology, Louisiana State University Health Sciences Center-Shreveport, LA, United States.
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Abstract
The identification of endogenous proteins as well as their binding to metal ions in living cells is determined by combining pulsed electrophoretic separations with nanoelectrospray ionization followed by mass spectrometric detection. This approach avoids problems resulting from the complicated cellular environment. In this manner, we demonstrate the rapid identification (300 ms or less) of intact proteins from living E. coli cells including the complexation of calmodulin with calcium ion. The latter showed different binding states from those observed in in vitro studies. These observations also reveal in vitro measurements do not necessarily represent the actual situation in living cells. We conclude that the attempted in situ measurement of intracellular proteins with minimal sampling processes should be preferred.
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Affiliation(s)
- Gongyu Li
- Department of Chemistry, School of Chemistry and Materials Science, University of Science and Technology of China , Hefei, Anhui 230026, P. R. China
| | - Siming Yuan
- Department of Chemistry, School of Chemistry and Materials Science, University of Science and Technology of China , Hefei, Anhui 230026, P. R. China
| | - Yang Pan
- National Synchrotron Radiation Laboratory, University of Science and Technology of China , Hefei, Anhui 230029, P. R. China
| | - Yangzhong Liu
- Department of Chemistry, School of Chemistry and Materials Science, University of Science and Technology of China , Hefei, Anhui 230026, P. R. China
| | - Guangming Huang
- Department of Chemistry, School of Chemistry and Materials Science, University of Science and Technology of China , Hefei, Anhui 230026, P. R. China
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7
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Hogeback J, Schwarzer M, Wehe CA, Sperling M, Karst U. Investigating the adduct formation of organic mercury species with carbonic anhydrase and hemoglobin from human red blood cell hemolysate by means of LC/ESI-TOF-MS and LC/ICP-MS. Metallomics 2016; 8:101-7. [PMID: 26442983 DOI: 10.1039/c5mt00186b] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The interaction of mercury species with human erythrocytes is studied to investigate possible high molecular binding partners for mercury species. Human blood hemolysate was spiked with methylmercury and investigated by means of liquid chromatography (LC) coupled to electrospray ionization time of flight mass spectrometry (ESI-ToF-MS) and inductively coupled plasma mass spectrometry (ICP-MS). Beside adduct formation of mercury species with hemoglobin, the main compound of the erythrocytes, mercury binding to the enzyme carbonic anhydrase was revealed. Due to an enzymatic digest of the protein-mercury adduct, the binding site at the free thiol group of the protein was identified. These results indicate that carbonic anhydrase might play a role in mercury toxicity.
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Affiliation(s)
- Jens Hogeback
- Institute of Inorganic and Analytical Chemistry, University of Münster, Corrensstraße 28/30, 48149 Münster, Germany.
| | - Miriam Schwarzer
- Institute of Inorganic and Analytical Chemistry, University of Münster, Corrensstraße 28/30, 48149 Münster, Germany.
| | - Christoph A Wehe
- Institute of Inorganic and Analytical Chemistry, University of Münster, Corrensstraße 28/30, 48149 Münster, Germany.
| | - Michael Sperling
- Institute of Inorganic and Analytical Chemistry, University of Münster, Corrensstraße 28/30, 48149 Münster, Germany. and European Virtual Institute for Speciation Analysis (EVISA), Mendelstr. 11, 48149 Münster, Germany
| | - Uwe Karst
- Institute of Inorganic and Analytical Chemistry, University of Münster, Corrensstraße 28/30, 48149 Münster, Germany.
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Redman EA, Ramos-Payan M, Mellors JS, Ramsey JM. Analysis of Hemoglobin Glycation Using Microfluidic CE-MS: A Rapid, Mass Spectrometry Compatible Method for Assessing Diabetes Management. Anal Chem 2016; 88:5324-30. [PMID: 27100069 DOI: 10.1021/acs.analchem.6b00622] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Diabetes has become a significant health problem worldwide with the rate of diagnosis increasing rapidly in recent years. Measurement of glycated blood proteins, particularly glycated hemoglobin (HbA1c), is an important diagnostic tool used to detect and manage the condition in patients. Described here is a method using microfluidic capillary electrophoresis with mass spectrometry detection (CE-MS) to assess hemoglobin glycation in whole blood lysate. Using denaturing conditions, the hemoglobin (Hb) tetramer dissociates into the alpha and beta subunits (α- and β-Hb), which are then separated via CE directly coupled to MS detection. Nearly baseline resolution is achieved between α-Hb, β-Hb, and glycated β-Hb. A second glycated β-Hb isomer that is partially resolved from β-Hb is detected in extracted ion electropherograms for glycated β-Hb. Glycation on α-Hb is also detected in the α-Hb mass spectrum. Additional modifications to the β-Hb are detected, including acetylation and a +57 Da species that could be the addition of a glyoxal moiety. Patient blood samples were analyzed using the microfluidic CE-MS method and a clinically used immunoassay to measure HbA1c. The percentage of glycated α-Hb and β-Hb was calculated from the microfluidic CE-MS data using peak areas generated from extracted ion electropherograms. The values for glycated β-Hb were found to correlate well with the HbA1c levels derived in the clinic, giving a slope of 1.20 and an R(2) value of 0.99 on a correlation plot. Glycation of human serum albumin (HSA) can also be measured using this technique. It was observed that patients with elevated glycated Hb levels also had higher levels of HSA glycation. Interestingly, the sample with the highest HbA1c levels did not have the highest levels of glycated HSA. Because the lifetime of HSA is shorter than Hb, this could indicate a recent lapse in glycemic control for that patient. The ability to assess both Hb and HSA glycation has the potential to provide a more complete picture of a patient's glycemic control in the months leading up to blood collection. The results presented here demonstrate that the microfluidic CE-MS method is capable of rapidly assessing Hb and HSA glycation from low volumes of whole blood with minimal sample preparation and has the potential to provide more information in a single analysis step than current technologies.
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9
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Moini M, Martinez B. Ultrafast capillary electrophoresis/mass spectrometry with adjustable porous tip for a rapid analysis of protein digest in about a minute. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2014; 28:305-310. [PMID: 24375882 DOI: 10.1002/rcm.6786] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Revised: 11/07/2013] [Accepted: 11/12/2013] [Indexed: 06/03/2023]
Abstract
RATIONALE This paper introduces a novel ultrafast capillary electrophoresis (UFCE) mass spectrometry (MS) method comprised of a short (< 20 cm) and narrow (≤ 5 µm) capillary, with an integrated porous segment at the terminus of the capillary, for sheathless interfacing of CE to MS. The sheathless nature of the interface minimizes dead volume which is particularly important for ultrafast CE because of the small diameters of the capillaries. METHODS The separation voltage across the capillary was set to produce an electric field of ≥1000 V/cm to provide an analysis time of approximately 1 min. For the analysis of peptides and protein digests, a background electrolyte containing 0.1% cationic polymer (polybrene or Poly-E) in 0.1% acetic acid in water was used to prevent analyte-wall interaction. RESULTS Uniquely, the porous tip of the capillary is adjustable. This allows the porous tip to be pulled inside the sheath liquid for sample stacking during injection, or sample focusing in isoelectric focusing (IEF), or, alternatively, pushed outside of the sheath liquid for electrospray ionization (ESI). The adjustable interface preserves electrical conductivity during electrokinetic injection with reverse electro-osmotic flow. Therefore, pre-concentration of analytes at the capillary inlet is achieved without the need to disassemble the interface, improving the throughput. CONCLUSIONS As a proof of concept, the application of UFCE-MS was demonstrated by the analysis of a peptide mixture and a protein digest in ~1 min.
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Affiliation(s)
- Mehdi Moini
- Museum Conservation Institute, Smithsonian Institution, Suitland, MD, USA
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Ito E, Nakajima K, Waki H, Miseki K, Shimada T, Sato TA, Kakehi K, Suzuki M, Taniguchi N, Suzuki A. Structural Characterization of Pyridylaminated Oligosaccharides Derived from Neutral Glycosphingolipids by High-Sensitivity Capillary Electrophoresis–Mass Spectrometry. Anal Chem 2013; 85:7859-65. [DOI: 10.1021/ac401460f] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Emi Ito
- Systems Glycobiology Research
Group, RIKEN−Max Planck Joint Research Center, Global Research
Cluster, RIKEN, 2-1 Hirosawa, Wako-shi,
Saitama 351-0198, Japan
| | - Kazuki Nakajima
- Systems Glycobiology Research
Group, RIKEN−Max Planck Joint Research Center, Global Research
Cluster, RIKEN, 2-1 Hirosawa, Wako-shi,
Saitama 351-0198, Japan
| | - Hiroaki Waki
- Analytical Division, Shimadzu Corporation, 1 Nishinokyo-Ku, Kuwabaracho,
Nakagyo-ku, Kyoto 604-8511, Japan
| | - Kozo Miseki
- Analytical Division, Shimadzu Corporation, 1 Nishinokyo-Ku, Kuwabaracho,
Nakagyo-ku, Kyoto 604-8511, Japan
| | - Takashi Shimada
- Life Science Research Center, Shimadzu Corporation, 5-1-1 Tsukiji, Chuo-ku, Tokyo
105-0045, Japan
| | - Taka-Aki Sato
- Life Science Research Center, Shimadzu Corporation, 5-1-1 Tsukiji, Chuo-ku, Tokyo
105-0045, Japan
| | - Kazuaki Kakehi
- School
of Pharmacy, Kinki University, 3-4-1 Kowakae,
Higashi-Osaka 577-8502,
Japan
| | - Minoru Suzuki
- Life Science Research Center, Shimadzu Corporation, 5-1-1 Tsukiji, Chuo-ku, Tokyo
105-0045, Japan
| | - Naoyuki Taniguchi
- Systems Glycobiology Research
Group, RIKEN−Max Planck Joint Research Center, Global Research
Cluster, RIKEN, 2-1 Hirosawa, Wako-shi,
Saitama 351-0198, Japan
| | - Akemi Suzuki
- Institute of Glycoscience, Tokai University, 4-1-1 Kitakaname, Hiratsuka, Kanagawa,
259-1292, Japan
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11
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Harrison CR. Role of Capillary Electrophoresis in the Fight Against Doping in Sports. Anal Chem 2013; 85:6982-7. [DOI: 10.1021/ac302821x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Christopher R. Harrison
- Department of Chemistry and Biochemistry, San Diego State University, 5500 Campanile Drive, San Diego, California
92182, United States
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Moini M. High-throughput capillary electrophoresis-mass spectrometry: from analysis of amino acids to analysis of protein complexes. Methods Mol Biol 2013; 984:79-119. [PMID: 23386339 DOI: 10.1007/978-1-62703-296-4_8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Recent advances in capillary electrophoresis-mass spectrometry (CE-MS) interfacing using porous tip is leading to commercialization of CE-MS with a sheathless interface for the first time. The new sheathless interface in conjunction with CE capillary coatings using self-coating background electrolytes (BGE) has significantly simplified CE-MS analysis of complex mixtures. CE-MS, with its high separation efficiency, compound identification capability, and ability to rapidly separate compounds with a wide range of mass and charge while consuming only nanoliters of samples, has become a valuable analytical technique for the analysis of complex biological mixtures. These advances have allowed a single capillary to analyze a range of compounds including amino acids, their D/L enantiomers, protein digests, intact proteins, and protein complexes. With these capabilities, CE-MS is poised to become the multipurpose tool of separation scientists. More recently, an eight-capillary CE in conjunction with an 8-inlet mass spectrometry has allowed 8 CE-MS analyses to be performed concurrently, significantly increasing throughput.
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MESH Headings
- Amino Acids/chemistry
- Amino Acids/isolation & purification
- Animals
- Coordination Complexes/chemistry
- Coordination Complexes/isolation & purification
- Crown Ethers
- Electrolytes/chemistry
- Electrophoresis, Capillary/instrumentation
- Electrophoresis, Capillary/methods
- Electrophoresis, Capillary/standards
- Erythrocytes/chemistry
- Humans
- Limit of Detection
- Metalloproteins/chemistry
- Metalloproteins/isolation & purification
- Multiprotein Complexes/isolation & purification
- Porosity
- Reference Standards
- Sequence Analysis, Protein
- Spectrometry, Mass, Electrospray Ionization/instrumentation
- Spectrometry, Mass, Electrospray Ionization/methods
- Spectrometry, Mass, Electrospray Ionization/standards
- Stereoisomerism
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Affiliation(s)
- Mehdi Moini
- Museum Conservation Institute, Smithsonian Institution, Suitland, MD, USA.
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13
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Bonvin G, Schappler J, Rudaz S. Capillary electrophoresis–electrospray ionization-mass spectrometry interfaces: Fundamental concepts and technical developments. J Chromatogr A 2012; 1267:17-31. [DOI: 10.1016/j.chroma.2012.07.019] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2012] [Revised: 07/04/2012] [Accepted: 07/06/2012] [Indexed: 01/24/2023]
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Moini M, Jiang L, Bootwala S. High-throughput analysis using gated multi-inlet mass spectrometry. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2011; 25:789-794. [PMID: 21337641 DOI: 10.1002/rcm.4924] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Gated multi-inlet mass spectrometry is introduced for high-throughput chemical analysis. In this design, multiple high-pressure liquid chromatography (HPLC) columns or capillary electrophoresis (CE) capillaries are attached to multiple electrosprayers (one for each column or capillary) that spray toward a gated multi-inlet time-of-flight mass spectrometer (TOF-MS). Although all of the sprayers are spraying continuously, only one inlet is exposed at any given time for a specific duration set by the MS data system. The gated multi-sprayer, multi-inlet design significantly enhances the performance of the multi-ESI, multi-inlet TOF-MS with minimal cost and reduces analysis time. The gated multi-sprayer, multi-inlet design was applied to the investigation of column-to-column reproducibility of multiple HPLCs using a peptide mixture and to the simultaneous analysis of four protein digests. In addition, it was applied to the analysis of peptide mixtures using eight CE capillaries. The gated multi-inlet MS has several advantages compared to our previous non-gated multi-inlet MS. For example, because only one inlet is open at one time, the original manufacturer's inlet inner diameter and pumping system can be used, which enhances the sensitivity of detection for each inlet and minimizes the manufacturing cost. In addition, the number of inlets can be increased as desired. The maximum number of liquid streams that can be concurrently analyzed is limited by: (1) the number of inlets, (2) the chromatographic (electrophoretic) peak width, and (3) how fast the gate can move from one position to the next.
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Affiliation(s)
- Mehdi Moini
- Museum Conservation Institute, Smithsonian Institution, Suitland, MD 20746-2863, USA.
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15
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Single cell analytics: an overview. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2010; 124:99-122. [PMID: 21072695 DOI: 10.1007/10_2010_96] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The research field of single cell analysis is rapidly expanding, driven by developments in flow cytometry, microscopy, lab-on-a-chip devices, and many other fields. The promises of these developments include deciphering cellular mechanisms and the quantification of cell-to-cell differences, ideally with spatio-temporal resolution. However, these promises are challenging as the analytical techniques have to cope with minute analyte amounts and concentrations. We formulate first these challenges and then present state-of-the-art analytical techniques available to investigate the different cellular hierarchies--from the genome to the phenome, i.e., the sum of all phenotypes.
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Huhn C, Ramautar R, Wuhrer M, Somsen GW. Relevance and use of capillary coatings in capillary electrophoresis–mass spectrometry. Anal Bioanal Chem 2009; 396:297-314. [DOI: 10.1007/s00216-009-3193-y] [Citation(s) in RCA: 154] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2009] [Revised: 09/22/2009] [Accepted: 09/24/2009] [Indexed: 11/24/2022]
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17
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Ahmed FE. The role of capillary electrophoresis–mass spectrometry to proteome analysis and biomarker discovery. J Chromatogr B Analyt Technol Biomed Life Sci 2009; 877:1963-81. [DOI: 10.1016/j.jchromb.2009.05.023] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2008] [Revised: 04/24/2009] [Accepted: 05/10/2009] [Indexed: 01/25/2023]
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18
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Pantůčková P, Gebauer P, Boček P, Křivánková L. Electrolyte systems for on-line CE-MS: Detection requirements and separation possibilities. Electrophoresis 2009; 30:203-14. [DOI: 10.1002/elps.200800262] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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19
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Nguyen A, Moini M. Analysis of Major Protein−Protein and Protein−Metal Complexes of Erythrocytes Directly from Cell Lysate Utilizing Capillary Electrophoresis Mass Spectrometry. Anal Chem 2008; 80:7169-73. [DOI: 10.1021/ac801158q] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- An Nguyen
- Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712
| | - Mehdi Moini
- Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712
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20
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Gaspar A, Englmann M, Fekete A, Harir M, Schmitt-Kopplin P. Trends in CE-MS 2005–2006. Electrophoresis 2008; 29:66-79. [DOI: 10.1002/elps.200700721] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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21
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Haselberg R, de Jong GJ, Somsen GW. Capillary electrophoresis–mass spectrometry for the analysis of intact proteins. J Chromatogr A 2007; 1159:81-109. [PMID: 17560583 DOI: 10.1016/j.chroma.2007.05.048] [Citation(s) in RCA: 120] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2007] [Revised: 05/01/2007] [Accepted: 05/15/2007] [Indexed: 10/23/2022]
Abstract
Developments in the fields of protein chemistry, proteomics and biotechnology have increased the demand for suitable analytical techniques for the analysis of intact proteins. In 1989, capillary electrophoresis (CE) was combined with mass spectrometry (MS) for the first time and its potential usefulness for the analysis of intact (i.e. non-digested) proteins was shown. This article provides an overview of the applications of CE-MS within the field of intact protein analysis. The principles of the applied CE modes and ionization techniques used for CE-MS of intact proteins are shortly described. It is shown that separations are predominantly carried out by capillary zone electrophoresis and capillary isoelectric focusing, whereas electrospray ionization (ESI) and matrix-assisted laser desorption ionization (MALDI) are the most popular ionization techniques used for interfacing. The combination of CE with inductively coupled plasma (ICP) MS for the analysis of metalloproteins is also discussed. The various CE-MS combinations are systematically outlined and tables provide extensive overviews of the applications of each technique for intact protein analysis. Selected examples are given to illustrate the usefulness of the CE-MS techniques. Examples include protein isoform assignment, single cell analysis, metalloprotein characterization, proteomics and biomarker screening. Finally, chip-based electrophoresis combined with MS is shortly treated and some of its applications are described. It is concluded that CE-MS represents a powerful tool for the analysis of intact proteins yielding unique separations and information.
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Affiliation(s)
- Rob Haselberg
- Department of Biomedical Analysis, Utrecht University, 3508 TB Utrecht, The Netherlands.
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22
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Moini M. Simplifying CE−MS Operation. 2. Interfacing Low-Flow Separation Techniques to Mass Spectrometry Using a Porous Tip. Anal Chem 2007; 79:4241-6. [PMID: 17447730 DOI: 10.1021/ac0704560] [Citation(s) in RCA: 242] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A robust, reproducible, and single-step interface design between low flow rate separation techniques, such as sheathless capillary electrophoresis (CE) and nanoliquid chromatography (nLC), and mass spectrometry (MS) using electrospray ionization (ESI), is introduced. In this design, the electrical connection to the capillary outlet was achieved through a porous tip at the capillary outlet. The porous section was created by removing 1-1.5 in. of the polyimide coating of the capillary and etching this section by 49% solution of HF until it is porous. The electrical connection to the capillary outlet is achieved simply by inserting the capillary outlet containing the porous tip into the existing ESI needle (metal sheath) and filling the needle with the background electrolyte. Redox reactions of water at the ESI needle and transport of these small ions through the porous tip into the capillary provides the electrical connection for the ESI and for the CE outlet electrode. The etching process reduces the wall thickness of the etched section, including the tip of the capillary, to 5-10 microm, which for a 20-30 microm i.d. capillary results in stable electrospray at approximately 1.5 kV. The design is suitable for interfacing a wide range of capillary sizes with a wide range of flow rates to MS via ESI, but it is especially useful for interfacing narrow (<30 microm i.d.) capillaries and low flow rates (<100 nL/min). The advantages of the porous tip design include the following: (1) its fabrication is reproducible, can be automated, and does not require any mechanical tools. (2) The etching process reduces the tip outer diameter and makes the capillary porous in one step. (3) The interface can be used for both nLC-MS and CE-MS. (4) If blocked or damaged, a small section of the tip can be etched off without any loss of performance. (5) The interface design leaves the capillary inner wall intact and, therefore, does not add any dead volume to the CE-MS or nLC-MS interface. (6) Bubble formation due to redox reactions of water at the high-voltage electrode is outside of the separation capillary and does not affect separation or MS performances. The performance of this interface is demonstrated by the analyses of amino acids, peptide, and protein mixtures.
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Affiliation(s)
- Mehdi Moini
- Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712, USA.
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23
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Garza S, Chang S, Moini M. Simplifying capillary electrophoresis-mass spectrometry operation: eliminating capillary derivatization by using self-coating background electrolytes. J Chromatogr A 2007; 1159:14-21. [PMID: 17335833 DOI: 10.1016/j.chroma.2007.02.038] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2006] [Revised: 01/30/2007] [Accepted: 02/14/2007] [Indexed: 11/24/2022]
Abstract
To simplify capillary electrophoresis-mass spectrometry (CE-MS) operation, a background electrolyte (BGE) containing a polymer additive is introduced that allows the analysis of peptides and protein mixtures in underivatized fused-silica capillaries without any pretreatment, thereby increasing throughput. The most important characteristic of these polymer additives is that they do not significantly suppress the signals of the proteins and peptides under electrospray ionization, thereby allowing them to be used as an additive to common BGEs that are used for CE-MS analysis of peptide and protein mixtures. In addition, because the fused-silica capillary inner wall is continuously coated with the polymer additive, migration irreproducibility, due to the degradation of the capillary inner wall coating, under CE-MS is minimized. High sensitivity of detection, migration reproducibility, and ease of fabrication allow CE-MS analyses that require long analysis time, such as (CE-MS/MS)n, to be performed with ease. The utility of this background electrolyte has been demonstrated for the analysis of complex protein digests and intact proteins.
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Affiliation(s)
- Selynda Garza
- Department of Chemistry and Biochemistry, The University of Texas at Austin, Austin, TX 78712, USA
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24
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Huang YF, Chang HT. Nile Red-Adsorbed Gold Nanoparticle Matrixes for Determining Aminothiols through Surface-Assisted Laser Desorption/Ionization Mass Spectrometry. Anal Chem 2006; 78:1485-93. [PMID: 16503598 DOI: 10.1021/ac0517646] [Citation(s) in RCA: 200] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This paper describes the use of Nile Red-adsorbed gold nanoparticles (NRAuNPs) as selective probes and matrixes for the determination of aminothiols through surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS). The binding of three aminothiols-glutathione (GSH), cysteine (Cys), and homocysteine (HCys)-to the surfaces of these NRAuNPs induces their aggregation, which causes asubsequent changes in their color and fluorescence. Because arginine-a non-thiol amino acid-does not induce such aggregation, it is a straightforward process to use the NRAuNPs to selectively concentrate the aminothiols from a solution containing all four of these analytes; we were able to identify the three aminothiols in the precipitate, and arginine in the supernatant, directly through SALDI-MS measurements. Without using this preconcentration approach, the limits of detection (LODs) at a signal-to-noise ratio of 3 were 1.0, 2.0, and 1.3 microM for GSH, Cys, and HCys, respectively. In comparison, selective concentration using the NRAuNPs provided LODs of 25, 54, and 34 nM, for the determinations of GSH, Cys, and HCys, respectively. NRAuNP matrixes provide a number of advantages over the use of conventional organic matrixes (e.g., 2,5-dihydroxybenzoic acid), such as ease of preparation, selectivity, sensitivity, and repeatability. We validated the applicability of our method through the analyses of GSH in red blood cells and of Cys in plasma; we believe that this approach has great potential for diagnosis.
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Affiliation(s)
- Yu-Fen Huang
- Department of Chemistry, National Taiwan University, 1, Section 4, Roosevelt Road, Taipei, Taiwan
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25
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Huang YF, Hsieh MM, Tseng WL, Chang HT. On-Line Concentration of Microheterogeneous Proteins by Capillary Electrophoresis Using SDS and PEO as Additives. J Proteome Res 2006; 5:429-36. [PMID: 16457610 DOI: 10.1021/pr050298y] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this paper, we describe a method for analyzing large-volume protein samples using capillary electrophoresis in conjunction with laser-induced fluorescence detection (CE-LIF). To improve the stacking and separation efficiencies of proteins, we added either 0.01% sodium dodecyl sulfate (SDS) or 0.01% poly(ethylene oxide) (PEO) to the Tris-borate solutions (pH 10.0) used to prepare the protein samples. After injection of the large-volume samples (ca. 1.0 microL, 0.1 microM), the proteins migrate against the electroosmotic flow (EOF) and enter the PEO zone; this process causes them to slow and stack at the boundary between the PEO and sample zones. As a result, the limits of detection (LODs) at a signal-to-noise (S/N) of 3 for most proteins are sub-nM to several nM. For instance, the LOD (S/N = 3) for alpha-lactalbumin is 0.48 nM, which is an 84-fold sensitivity enhancement over the traditional method. By applying a short plug of 0.2% SDS prior to sample injection, a greater number of peaks, representing the microheterogeneity of the proteins, were resolved and the stacking efficiency of the proteins increased slightly. This method allowed us to detect 12 peaks when injecting a large volume of sample containing six model proteins (0.1 microM). We also analyzed the microheterogeneities of the proteins by using CE with UV-Vis absorption detection when injecting a large volume of sample containing six model proteins (1.0 microM) in the presence of a 1.0% SDS plug. The practical method is validated by the detection of human serum albumin in a urine sample, obtained from a healthy female, without sample pretreatment; its concentration was 0.18 microM. We further demonstrate the capability of this method to detect low amounts of proteins through the detection of 45 nM hemoglobin after injecting ca. 1.0 microL of ultradilute lysed red blood cells. The experimental results indicate that our proposed method has great potential for use in diagnosis and proteomics applications.
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Affiliation(s)
- Yu-Fen Huang
- Department of Chemistry, National Taiwan University, Taipei, Taiwan
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26
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Stutz H. Advances in the analysis of proteins and peptides by capillary electrophoresis with matrix-assisted laser desorption/ionization and electrospray-mass spectrometry detection. Electrophoresis 2005; 26:1254-90. [PMID: 15776483 DOI: 10.1002/elps.200410130] [Citation(s) in RCA: 135] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
High throughput, outstanding certainty in peptide/protein identification, exceptional resolution, and quantitative information are essential pillars in proteome research. Capillary electrophoresis (CE) coupled to mass spectrometry (MS) has proven to meet these requirements. Soft ionization techniques, such as matrix-assisted laser desorption/ionization (MALDI) and electrospray ionization (ESI), have paved the way for the story of success of CE-MS in the analysis of biomolecules and both approaches are subject of discussion in this article. Meanwhile, CE-MS is far away from representing a homogeneous field. Therefore the review will cover a vast area including the coupling of different modes of CE (capillary zone electrophoresis, capillary isoelectric foscusing, capillary electrochromatography, micellar electrokinetic chromatography, nonaqueous capillary electrophoresis) to MS as well as on-line preconcentration techniques (transient capillary isotachophoresis, solid-phase extraction, membrane preconcentration) applied to compensate for restricted detection sensitivity. Special attention is given to improvements in interfacing, namely addressing nanospray and coaxial sheath liquid design. Peptide mapping, collision-induced dissociation with subsequent tandem MS, and amendments in mass accuracy of instruments improve information validity gained from MS data. With 2-D on-line coupling of liquid chromatography (LC) and CE a further topic will be discussed. A special section is dedicated to recent attempts in establishing CE-ESI-MS in proteomics, in the clinical and diagnostic field, and in the food sector.
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Affiliation(s)
- Hanno Stutz
- University of Salzburg, Department of Molecular Biology, Division of Chemistry, Salzburg, Austria.
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27
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Simó C, Herrero M, Neusüss C, Pelzing M, Kenndler E, Barbas C, Ibáñez E, Cifuentes A. Characterization of proteins fromSpirulina platensis microalga using capillary electrophoresis-ion trap-mass spectrometry and capillary electrophoresis-time of flight-mass spectrometry. Electrophoresis 2005; 26:2674-83. [PMID: 15929060 DOI: 10.1002/elps.200500055] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
In this work, a new capillary electrophoresis-mass spectrometry (CE-MS) procedure is developed to analyze proteins in Spirulina platensis microalgae. It is demonstrated that a fine optimization of several separation parameters is essential in order to achieve suitable CE-MS analysis of these proteins in natural extracts from microalgae. Namely, optimization of the composition of the separation buffer, electrospray conditions, and washing routine between runs are required in order to obtain reliable and reproducible CE-MS analyses of the main proteins found in this microalga (namely, allophycocyanin-alpha chain, allophycocyanin-beta, c-phycocyanin-alpha, and c-phycocyanin-beta). The relative molecular mass of these biopolymers is determined using two different MS instruments coupled to CE, i.e., CE-ion trap-MS and CE-time of flight-MS (CE-TOF-MS). A comparison between the results obtained with both instruments is carried out. The high resolution of the TOF-MS enables the distinction of small modifications in proteins and, thus, a more accurate mass determination. Interestingly, molecular mass values obtained by both CE-MS procedures agree very well while these experimental values are only in partial agreement with those theoretically expected (i.e., genetically derived masses). Some protein modifications due to amino acids exchange induced by nucleotide codon mutations are proposed to explain this difference.
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Affiliation(s)
- Carolina Simó
- Department of Food Analysis, Institute of Industrial Fermentations (CSIC), Madrid, Spain
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28
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Shamsi SA, Miller BE. Capillary electrophoresis-mass spectrometry: recent advances to the analysis of small achiral and chiral solutes. Electrophoresis 2005; 25:3927-61. [PMID: 15597424 DOI: 10.1002/elps.200406131] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
We describe here the state-of-the-art development of on-line capillary electrophoresis-mass spectrometry (CE-MS) over the last two years. Technological developments included are novel designs of new interfaces and ionization sources, new capillary coatings, buffers, and micelles as well as application of various modes of CE-MS published in the recent literature. The areas of CE-MS application in analysis of small achiral and chiral solutes are covered in sections that highlight the recent advances and possibilities of each mode of CE-MS. Application areas reviewed in this paper include achiral and chiral pharmaceuticals, agrochemicals, carbohydrates, and small peptides. The separation of enantiomers using micellar electrokinetic chromatography (MEKC)-MS with molecular micelles and capillary electrochromatography (CEC)-MS using pack tapered columns appears to provide good tolerance to electrospray stability for routine on-line CE-MS. These two modes seem to be very suitable for sensitive detection of chiral pharmaceuticals in biological samples, but their use will probably increase in the near future. Overall, it seems that one mode of CE-MS, in particular capillary zone electrophoresis (CZE)-MS, is now recognized as established technique for analysis of small charged solutes, but other modes, such as MEKC-MS and CEC-MS, are still within a period of development in terms of both MS-compatible pseudostationary phases and columns as well as applications.
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Affiliation(s)
- Shahab A Shamsi
- Department of Chemistry, Center of Biotechnology and Drug Design, Georgia State University, Atlanta, GA 30303, USA.
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29
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Simpson DC, Smith RD. Combining capillary electrophoresis with mass spectrometry for applications in proteomics. Electrophoresis 2005; 26:1291-305. [PMID: 15765477 DOI: 10.1002/elps.200410132] [Citation(s) in RCA: 159] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Mass spectrometry (MS)-based proteomics is currently dominated by the analysis of peptides originating either from digestion of proteins separated by two-dimensional gel electrophoresis (2-DE) or from global digestion; the simple peptide mixtures obtained from digestion of gel-separated proteins do not usually require further separation, while the complex peptide mixtures obtained by global digestion are most frequently separated by chromatographic techniques. Capillary electrophoresis (CE) provides alternatives to 2-DE for protein separation and alternatives to chromatography for peptide separation. This review attempts to elucidate how the most promising CE modes, capillary zone electrophoresis (CZE) and capillary isoelectric focusing (CIEF), might best be applied to MS-based proteomics. CE-MS interfacing, mass analyzer performance, column coating to minimize analyte adsorption, and sample stacking for CZE are considered prior to examining numerous applications. Finally, multidimensional systems that incorporate CE techniques are examined; CZE often finds use as a fast, final dimension before ionization for MS, while CIEF, being an equilibrium technique, is well-suited to being the first dimension in automated fractionation systems.
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Monton MRN, Terabe S. Recent Developments in Capillary Electrophoresis-Mass Spectrometry of Proteins and Peptides. ANAL SCI 2005; 21:5-13. [PMID: 15675508 DOI: 10.2116/analsci.21.5] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Many researchers have invested considerable efforts toward improving capillary electrophoresis (CE)-mass spectrometry (MS) systems so they can be applied better to standard analyses. This review highlights the developments in CE-MS of proteins and peptides over the last five years. It includes the developments in interfaces, sample-enrichment techniques, microfabricated devices, and some applications, largely in capillary zone electrophoresis (CZE), capillary isoelectric focusing (CIEF) and capillary isotachophoresis formats.
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Affiliation(s)
- Maria Rowena N Monton
- Graduate School of Material Science, University of Hyogo, Kamigori, Hyogo 678-1297, Japan.
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31
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Sheathless electrospray ionization interfaces for capillary electrophoresis–mass spectrometric detection. J Chromatogr A 2004. [DOI: 10.1016/j.chroma.2004.08.116] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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32
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Moini M, Huang H. Application of capillary electrophoresis/ electrospray ionization-mass spectrometry to subcellular proteomics ofEscherichia coli ribosomal proteins. Electrophoresis 2004; 25:1981-1987. [PMID: 15237397 DOI: 10.1002/elps.200305906] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We introduce capillary electrophoresis-mass spectrometry (CE-MS) as an efficient means for the on-line separation and identification of protein mixtures. It was found that while CE/electrospray ionization (ESI)-MS analysis of whole-cell lysate was too complicated for the one-dimensional CE-MS analysis, the technique was useful for the analysis of protein mixtures of moderate complexity (approximately 50 intact proteins). CE/ESI-MS was applied to the subcellular proteomics of ribosomal Escherichia coli. 55 out of the 56 ribosomal proteins were detected with ease by using only approximately 3.4 ng of ribosomal proteins. In addition, it was found that the mass accuracy of the conventional MS (such as quadrupole ion traps) was good enough to identify many post-translational modifications of the intact proteins by simply comparing their measured average molecular weight with the average molecular weight predicted from gene banks.
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Affiliation(s)
- Mehdi Moini
- Department of Chemistry and Biochemistry, The University of Texas at Austin, Austin, TX, USA
| | - Hsiaoling Huang
- Department of Chemistry and Biochemistry, The University of Texas at Austin, Austin, TX, USA
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33
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Moini M, Schultz CL, Mahmood H. CE/Electrospray Ionization-MS Analysis of Underivatized d/l-Amino Acids and Several Small Neurotransmitters at Attomole Levels through the Use of 18-Crown-6-tetracarboxylic Acid as a Complexation Reagent/Background Electrolyte. Anal Chem 2003; 75:6282-7. [PMID: 14616012 DOI: 10.1021/ac034708i] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A new capillary electrophoresis/mass spectrometry technique is introduced for attomole detection of primary amines (including several neurotransmitters), amino acids, and their d/l enantiomers in one run through the use of a complexation reagent while using only approximately 1 nL of sample. The technique uses underivatized amino acids in conjunction with an underivatized capillary, which significantly reduces cost and analysis time. It was found that when (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid (18-C-6-TCA, MW 440) was used as the background electrolyte/complexation reagent during the capillary electrophoresis/electrospray ionization-mass spectrometry (CE/ESI-MS) analysis of underivatized amino acids, stable complexes were formed between the amino acids and the 18-C-6-TCA molecules. These complexes, which exhibited high ionization efficiencies, were detectable at attomole levels for most amino acids. The detection limits of the AA/18-C-6-TCA complexes were on the average more than 2 orders of magnitude lower than that of the free amino acids in solution. In addition to lower detection limits under CE/ESI-MS, a solution of 18-C-6-TCA in the concentration range of 5-30 mM provided high separation efficiency for mixtures of l-amino acids as well as mixtures of d/l-amino acids. By using a solution of 18-C-6-TCA as the background electrolyte in conjunction with an underivatized, 130-cm-long, 20-microm-i.d., 150-microm-o.d. fused-silica capillary and by monitoring the m/z range of the amino acid/18-C-6-TCA complexes (m/z 515-700), most of the standard amino acids and many of their enantiomers were separated and detected with high separation efficiency and high sensitivity (nanomolar concentration detection limits) in one run. The solutions of 18-C-6-TCA also worked well as the CE/ESI-MS BGE for low-level detection of several neurotransmitters and some of their d/l enantiomers as well as for the analysis of amino acids at endogenous levels in lysed red blood cells.
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Affiliation(s)
- Mehdi Moini
- Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712, USA.
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Janini GM, Zhou M, Yu LR, Blonder J, Gignac M, Conrads TP, Issaq HJ, Veenstra TD. On-Column Sample Enrichment for Capillary Electrophoresis Sheathless Electrospray Ionization Mass Spectrometry: Evaluation for Peptide Analysis and Protein Identification. Anal Chem 2003; 75:5984-93. [PMID: 14588041 DOI: 10.1021/ac0301548] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Although several designs have been advanced for coupling sample enrichment devices to a sheathless electrospray ionization-mass spectrometry (MS) interface on a capillary electrophoresis (CE) column, most of these approaches suffer from difficulties in fabrication, and the CE separation efficiency is degraded as a result of the presence of coupling sleeves. We have developed a design that offers significant improvements in terms of ease of fabrication, durability, and maintenance of the integrity of the CE-separated analyte zones. Capillaries with different inside and outside diameters were evaluated to optimize the performance of the CE-MS system, resulting in a mass limit of detection of 500 amol for tandem MS analysis of a standard peptide using a 20-microm-i.d. capillary. The improved design incorporates an efficient method to preconcentrate a sample directly within the CE capillary followed by its electrophoretic separation and detection using a true zero dead-volume sheathless CE-MS interface. Testing of this novel CE-MS system showed its ability to characterize proteomic samples such as protein digests, in-gel-digested proteins, and hydrophobic peptides as well as to quantitate ICAT-labeled peptides.
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Affiliation(s)
- George M Janini
- Laboratory of Proteomics and Analytical Technologies and Image Analysis Laboratory, SAIC-Frederick, Inc., National Cancer Institute at Frederick, P.O. Box B, Frederick, Maryland 21702, USA.
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35
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Hummon AB, Sweedler JV, Corbin RW. Discovering new neuropeptides using single-cell mass spectrometry. Trends Analyt Chem 2003. [DOI: 10.1016/s0165-9936(03)00901-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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36
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Whitt JT, Moini M. Capillary electrophoresis to mass spectrometry interface using a porous junction. Anal Chem 2003; 75:2188-91. [PMID: 12720361 DOI: 10.1021/ac026380j] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A new capillary electrophoresis interface to electrospray ionization mass spectrometry (CE/ESI-MS) is introduced in which the electrical connection to the CE capillary outlet/ESI electrode is achieved by transfer of small ions related to the background electrolyte (BGE) through a porous section near the CE capillary outlet. In this design, only a small section of the capillary wall is made porous. The porous section is created by first thinning a small section of the capillary wall by drilling a well into it and then etching the remaining thin wall porous. This design has two advantages over previous designs (in which the whole circumference of the capillary was made porous): first, the capillary interface is more robust because only a small section of it is made porous, and therefore, no liquid junction is needed to secure the porous section. The electrical connection is achieved simply by inserting the capillary outlet containing the porous junction into the existing ESI needle and filling the needle with the BGE. Second, the time required to make the fused silica porous is reduced from approximately 1 h to a few minutes. In addition, there is no dead volume associated with the porous design, and because the actual metal/liquid contact occurs outside of the CE capillary, bubble formation due to redox reactions of water at the electrode does not affect CE/ESI-MS performance. The performance of this interface is demonstrated by the analyses of peptide and protein mixtures.
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Affiliation(s)
- Jacob T Whitt
- Department of Chemistry and Biochemistry, University of Texas at Austin, 78712, USA
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37
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Janini GM, Conrads TP, Wilkens KL, Issaq HJ, Veenstra TD. A sheathless nanoflow electrospray interface for on-line capillary electrophoresis mass spectrometry. Anal Chem 2003; 75:1615-9. [PMID: 12705593 DOI: 10.1021/ac020661+] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A novel, rugged capillary electrophoresis-electrospray ionization (CE-ESI) interface where the separation column, an electrical porous junction, and the spray tip are integrated on a single piece of a fused-silica capillary is described. ESI is accomplished by applying an electrical potential through an easily prepared porous junction across a 3-4-mm length of fused silica. A stable electrospray is produced at nanoflow rates generated in the capillary by electrophoretic and electroosmotic forces. The interface is particularly well suited for the detection of low-femtomole levels of proteins and peptides. The ruggedness of this interface was evident by the continuous operation of the same column for over a 2-week period with no detectable deterioration in separation or electrospray performance. The new interface was used for the LC-ESI-MS separation and analysis of peptides and proteins. Injection of 25 fmol of [Glu1]-fibrinopeptide B using the new device produced a CE-ESI-MS electropherogram with a signal-to-noise ratio of over 100 for this peptide.
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Affiliation(s)
- George M Janini
- Analytical Chemistry Laboratory, SAIC-Frederick, Inc., NCI-Frederick, Frederick, Maryland 21702, USA.
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Current literature in mass spectrometry. JOURNAL OF MASS SPECTROMETRY : JMS 2002; 37:1298-1307. [PMID: 12489092 DOI: 10.1002/jms.259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
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