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Warren CG, Dasgupta PK. Liquid phase detection in the miniature scale. Microfluidic and capillary scale measurement and separation systems. A tutorial review. Anal Chim Acta 2024; 1305:342507. [PMID: 38677834 DOI: 10.1016/j.aca.2024.342507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Revised: 03/18/2024] [Accepted: 03/19/2024] [Indexed: 04/29/2024]
Abstract
Microfluidic and capillary devices are increasingly being used in analytical applications while their overall size keeps decreasing. Detection sensitivity for these microdevices gains more importance as device sizes and consequently, sample volumes, decrease. This paper reviews optical, electrochemical, electrical, and mass spectrometric detection methods that are applicable to capillary scale and microfluidic devices, with brief introduction to the principles in each case. Much of this is considered in the context of separations. We do consider theoretical aspects of separations by open tubular liquid chromatography, arguably the most potentially fertile area of separations that has been left fallow largely because of lack of scale-appropriate detection methods. We also examine the theoretical basis of zone electrophoretic separations. Optical detection methods discussed include UV/Vis absorbance, fluorescence, chemiluminescence and refractometry. Amperometry is essentially the only electrochemical detection method used in microsystems. Suppressed conductance and especially contactless conductivity (admittance) detection are in wide use for the detection of ionic analytes. Microfluidic devices, integrated to various mass spectrometers, including ESI-MS, APCI-MS, and MALDI-MS are discussed. We consider the advantages and disadvantages of each detection method and compare the best reported limits of detection in as uniform a format as the available information allows. While this review pays more attention to recent developments, our primary focus has been on the novelty and ingenuity of the approach, regardless of when it was first proposed, as long as it can be potentially relevant to miniature platforms.
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Affiliation(s)
- Cable G Warren
- Department of Chemistry and Biochemistry, University of Texas at Arlington, Arlington, TX, 76019-0065, United States
| | - Purnendu K Dasgupta
- Department of Chemistry and Biochemistry, University of Texas at Arlington, Arlington, TX, 76019-0065, United States.
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2
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Schulze S, Pahl M, Stolz F, Appun J, Abel B, Schneider C, Belder D. Liquid Beam Desorption Mass Spectrometry for the Investigation of Continuous Flow Reactions in Microfluidic Chips. Anal Chem 2017; 89:6175-6181. [PMID: 28489359 DOI: 10.1021/acs.analchem.7b01026] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In this work, we present the combination of microfluidic chips and mass spectrometry employing laser-induced liquid beam ionization/desorption. The developed system was evaluated with respect to stable beam generation and laser parameters as well as solvent compatibility. The device was exemplarily applied to study a vinylogous Mannich reaction performed in continuous flow on chip. Fast processes can be observed with this technique which in the future could be beneficial for studying intermediates or contribute to the elucidation of reaction mechanisms.
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Affiliation(s)
- Sandra Schulze
- Institute of Analytical Chemistry, University Leipzig , Linnéstraße 3, 04103 Leipzig, Germany
| | - Maik Pahl
- Institute of Analytical Chemistry, University Leipzig , Linnéstraße 3, 04103 Leipzig, Germany
| | - Ferdinand Stolz
- Wilhelm-Ostwald-Institute of Physical and Theoretical Chemistry, University Leipzig , Linnéstraße 3, 04103 Leipzig, Germany.,Leibniz Institute of Surface Modification (IOM) , Permoserstraße 15, 04318 Leipzig, Germany
| | - Johannes Appun
- Institute of Organic Chemistry, University Leipzig , Johannisallee 29, 04103 Leipzig, Germany
| | - Bernd Abel
- Wilhelm-Ostwald-Institute of Physical and Theoretical Chemistry, University Leipzig , Linnéstraße 3, 04103 Leipzig, Germany.,Leibniz Institute of Surface Modification (IOM) , Permoserstraße 15, 04318 Leipzig, Germany
| | - Christoph Schneider
- Institute of Organic Chemistry, University Leipzig , Johannisallee 29, 04103 Leipzig, Germany
| | - Detlev Belder
- Institute of Analytical Chemistry, University Leipzig , Linnéstraße 3, 04103 Leipzig, Germany
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3
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Oukacine F, Quirino JP, Mesbah K, Taverna M. Capillary electrophoretic focusing of covalently derivatized protein induced by surfactant. Electrophoresis 2016; 37:1151-4. [DOI: 10.1002/elps.201600030] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Revised: 02/21/2016] [Accepted: 02/22/2016] [Indexed: 01/10/2023]
Affiliation(s)
- Farid Oukacine
- Université Grenoble Alpes; DPM UMR 5063; CNRS Grenoble France
| | - Joselito P. Quirino
- Australian Centre for Research on Separation Science, School of Physical Sciences-Chemistry; University of Tasmania; Hobart Tasmania Australia
| | - Kiarach Mesbah
- Inst Galien Paris Sud; Fac Pharm; 5 Rue JB Clement, F-92290 Chatenay Malabry France
| | - Myriam Taverna
- Inst Galien Paris Sud; Fac Pharm; 5 Rue JB Clement, F-92290 Chatenay Malabry France
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4
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Okamoto Y, Tsujimoto Y, Umakoshi H. Electrophoretic separation method for membrane pore-forming proteins in multilayer lipid membranes. Electrophoresis 2016; 37:762-8. [PMID: 26773565 DOI: 10.1002/elps.201500567] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Revised: 01/06/2016] [Accepted: 01/08/2016] [Indexed: 11/06/2022]
Abstract
In this paper, we report on a novel electrophoretic separation and analysis method for membrane pore-forming proteins in multilayer lipid membranes (MLMs) in order to overcome the problems related to current separation and analysis methods of membrane proteins, and to obtain a high-performance separation method on the basis of specific properties of the lipid membranes. We constructed MLMs, and subsequently characterized membrane pore-forming protein behavior in MLMs. Through the use of these MLMs, we were able to successfully separate and analyze membrane pore-forming proteins in MLMs. To the best of our knowledge, this research is the first example of membrane pore-forming protein separation in lipid membranes. Our method can be expected to be applied for the separation and analysis of other membrane proteins including intrinsic membrane proteins and to result in high-performance by utilizing the specific properties of lipid membranes.
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Affiliation(s)
- Yukihiro Okamoto
- Division of Chemical Engineering, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka, Japan
| | - Yusuke Tsujimoto
- Division of Chemical Engineering, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka, Japan
| | - Hiroshi Umakoshi
- Division of Chemical Engineering, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka, Japan
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5
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Schwarzkopf F, Scholl T, Ohla S, Belder D. Improving sensitivity in microchip electrophoresis coupled to ESI-MS/MS on the example of a cardiac drug mixture. Electrophoresis 2014; 35:1880-6. [DOI: 10.1002/elps.201300615] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Revised: 02/25/2014] [Accepted: 02/25/2014] [Indexed: 12/19/2022]
Affiliation(s)
| | - Tobias Scholl
- Institut für Analytische Chemie; Universität Leipzig; Leipzig Germany
| | - Stefan Ohla
- Institut für Analytische Chemie; Universität Leipzig; Leipzig Germany
| | - Detlev Belder
- Institut für Analytische Chemie; Universität Leipzig; Leipzig Germany
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6
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Hackl C, Beyreiss R, Geissler D, Jezierski S, Belder D. Rapid prototyping of electrochromatography chips for improved two-photon excited fluorescence detection. Anal Chem 2014; 86:3773-9. [PMID: 24666258 DOI: 10.1021/ac500793e] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In the present study, we introduce two-photon excitation at 532 nm for label-free fluorescence detection in chip electrochromatography. Two-photon excitation at 532 nm offers a promising alternative to one-photon excitation at 266 nm, as it enables the use of economic chip materials instead of fused silica. In order to demonstrate these benefits, one-photon and two-photon induced fluorescence detection are compared in different chip layouts and materials with respect to the achievable sensitivity in the detection of polycyclic aromatic hydrocarbons (PAHs). Customized chromatography chips with cover or bottom slides of different material and thickness are produced by means of a rapid prototyping method based on liquid-phase lithography. The design of thin bottom chips (180 μm) enables the use of high-performance immersion objectives with low working distances, which allows one to exploit the full potential of two-photon excitation for a sensitive detection. The developed method is applied for label-free analysis of PAHs separated on a polymer monolith inside polymer glass sandwich chips made from fused silica or soda-lime glass. The obtained limits of detection range from 40 nM to 1.95 μM, with similar sensitivities in fused silica thin bottom chips for one-photon and two-photon excitation. In deep-UV non- or less-transparent devices two-photon excitation is mandatory for label-free detection of aromatics with high sensitivity.
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Affiliation(s)
- Claudia Hackl
- Institut für Analytische Chemie, Universität Leipzig , Linnéstraße 3, 04103 Leipzig, Germany
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7
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Nie J, Kennedy RT. Capillary liquid chromatography fraction collection and postcolumn reaction using segmented flow microfluidics. J Sep Sci 2013; 36:3471-7. [PMID: 24039151 PMCID: PMC5641422 DOI: 10.1002/jssc.201300725] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Revised: 08/07/2013] [Accepted: 08/18/2013] [Indexed: 11/08/2022]
Abstract
A challenge for capillary LC (cLC) is fraction collection and the manipulation of fractions from microscale columns. An emerging approach is the use of segmented flow or droplet technology to perform such tasks. In this work, a fraction collection and postcolumn reaction system based on segmented flow was developed for the gradient cLC of proteins. In the system, column effluent and immiscible oil are pumped into separate arms of a tee resulting in regular fractions of effluent segmented by oil. Fractions were generated at 1 Hz corresponding to 5 nL volumes. The fraction collection rate was high enough to generate over 30 fractions per peak and preserve chromatographic resolution achieved for a five-protein test mixture. The resulting fractions could be stored and subsequently derivatized for fluorescence detection by pumping them into a second tee where naphthalene dicarboxyaldehyde, a fluorogenic reagent, was pumped into a second arm and added to each fraction. Proteins were derivatized within the droplets enabling postcolumn fluorescence detection of the proteins. The experiments demonstrate that fraction collection from cLC by segmented flow can be extended to proteins. Further, they illustrate a potential workflow for protein analysis based on postcolumn derivatization for fluorescence detection.
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Affiliation(s)
- Jing Nie
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109
| | - Robert T. Kennedy
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109
- Department of Pharmacology, University of Michigan, Ann Arbor, Michigan 48109
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8
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Beyreiss R, Geißler D, Ohla S, Nagl S, Posch TN, Belder D. Label-free fluorescence detection of aromatic compounds in chip electrophoresis applying two-photon excitation and time-correlated single-photon counting. Anal Chem 2013; 85:8150-7. [PMID: 23944704 DOI: 10.1021/ac4010937] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In this study, we introduce time-resolved fluorescence detection with two-photon excitation at 532 nm for label-free analyte determination in microchip electrophoresis. In the developed method, information about analyte fluorescence lifetimes is collected by time-correlated single-photon counting, improving reliable peak assignment in electrophoretic separations. The determined limits of detection for serotonin, propranolol, and tryptophan were 51, 37, and 280 nM, respectively, using microfluidic chips made of fused silica. Applying two-photon excitation microchip separations and label-free detection could also be performed in borosilicate glass chips demonstrating the potential for label-free fluorescence detection in non-UV-transparent devices. Microchip electrophoresis with two-photon excited fluorescence detection was then applied for analyses of active compounds in plant extracts. Harmala alkaloids present in methanolic plant extracts from Peganum harmala could be separated within seconds and detected with on-the-fly determination of fluorescence lifetimes.
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Affiliation(s)
- Reinhild Beyreiss
- Institut für Analytische Chemie, Universität Leipzig, Linnéstraße 3, 04103 Leipzig, Germany
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9
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Garrido-Medina R, Diez-Masa JC, de Frutos M. On-capillary fluorescent labeling and capillary electrophoresis laser-induced fluorescence analysis of glycoforms of intact prostate-specific antigen. Electrophoresis 2013; 34:2295-302. [DOI: 10.1002/elps.201200651] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Revised: 12/21/2012] [Accepted: 01/24/2013] [Indexed: 11/07/2022]
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10
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Wang C, Ouyang J, Ye DK, Xu JJ, Chen HY, Xia XH. Rapid protein concentration, efficient fluorescence labeling and purification on a micro/nanofluidics chip. LAB ON A CHIP 2012; 12:2664-71. [PMID: 22648530 DOI: 10.1039/c2lc20977b] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Fluorescence analysis has proved to be a powerful detection technique for achieving single molecule analysis. However, it usually requires the labeling of targets with bright fluorescent tags since most chemicals and biomolecules lack fluorescence. Conventional fluorescence labeling methods require a considerable quantity of biomolecule samples, long reaction times and extensive chromatographic purification procedures. Herein, a micro/nanofluidics device integrating a nanochannel in a microfluidics chip has been designed and fabricated, which achieves rapid protein concentration, fluorescence labeling, and efficient purification of product in a miniaturized and continuous manner. As a demonstration, labeling of the proteins bovine serum albumin (BSA) and IgG with fluorescein isothiocyanate (FITC) is presented. Compared to conventional methods, the present micro/nanofluidics device performs about 10(4)-10(6) times faster BSA labeling with 1.6 times higher yields due to the efficient nanoconfinement effect, improved mass, and heat transfer in the chip device. The results demonstrate that the present micro/nanofluidics device promises rapid and facile fluorescence labeling of small amount of reagents such as proteins, nucleic acids and other biomolecules with high efficiency.
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Affiliation(s)
- Chen Wang
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China
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11
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Garrido-Medina R, Díez-Masa JC, de Frutos M. CE methods for analysis of isoforms of prostate-specific antigen compatible with online derivatization for LIF detection. Electrophoresis 2011; 32:2036-43. [DOI: 10.1002/elps.201000524] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2010] [Revised: 01/28/2011] [Accepted: 01/29/2011] [Indexed: 11/08/2022]
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12
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Qiao X, Sun L, Wang L, Liang Y, Zhang L, Shan Y, Peng X, Liang Z, Zhang Y. High sensitive protein detection by hollow fiber membrane interface based protein enrichment and in situ fluorescence derivatization. J Chromatogr B Analyt Technol Biomed Life Sci 2011; 879:1439-43. [DOI: 10.1016/j.jchromb.2010.11.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2010] [Revised: 10/12/2010] [Accepted: 11/01/2010] [Indexed: 11/29/2022]
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13
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Kaneta T, Ogura T, Imasaka T. Analysis of proteins in biological samples by capillary sieving electrophoresis with postcolumn derivatization/laser-induced fluorescence detection. Electrophoresis 2011; 32:1061-7. [DOI: 10.1002/elps.201000488] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2010] [Revised: 11/06/2010] [Accepted: 11/19/2010] [Indexed: 11/09/2022]
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14
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Monson CF, Pace HP, Liu C, Cremer PS. Supported bilayer electrophoresis under controlled buffer conditions. Anal Chem 2011; 83:2090-6. [PMID: 21319743 DOI: 10.1021/ac1028819] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A pH controlled flow cell device was constructed to allow electrophoretic movement of charged lipids and membrane associated proteins in supported phospholipid bilayers. The device isolated electrolysis products near the electrodes from the electrophoresis process within the bilayer. This allowed the pH over the bilayer region to remain within ±0.2 pH units or better over many hours at salt concentrations up to 10 mM. Using this setup, it was found that the electrophoretic mobility of a dye conjugated lipid (Texas Red 1,2-dihexadecanoyl-sn-glycero-3-phosphoethanolamine (TR-DHPE)) was essentially constant between pH 3.3 and 9.3. In contrast, streptavidin, which was bound to biotinylated lipids, shifted from migrating cathodically at acidic pH values to migrating anodically under basic conditions. This shift was due to the modulation of the net charge on the protein, which changed the electrophoretic forces experienced by the macromolecule. The addition of a polyethylene glycol (PEG) cushion beneath the bilayer or the increase in the ionic strength of the buffer solution resulted in a decrease of the electroosmotic force experienced by the streptavidin with little effect on the Texas Red-DHPE. As such, it was possible in part to control the electrophoretic and electroosmotic contributions to streptavidin independently of one another.
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Affiliation(s)
- Christopher F Monson
- Department of Chemistry, Texas A&M University, 3255 TAMU, College Station, Texas 77843, United States
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15
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Dickerson JA, Dovichi NJ. Capillary sieving electrophoresis and micellar electrokinetic capillary chromatography produce highly correlated separation of tryptic digests. Electrophoresis 2010; 31:2461-4. [PMID: 20564272 DOI: 10.1002/elps.201000200] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
We perform 2-D capillary electrophoresis on fluorescently labeled proteins and peptides. Capillary sieving electrophoresis (CSE) was performed in the first dimension and MEKC was performed in the second. A cellular homogenate was labeled with the fluorogenic reagent FQ and separated using the system. This homogenate generated a pair of ridges; the first had essentially constant migration time in the CSE dimension, while the second had essentially constant migration time in the MEKC dimension. In addition, a few spots were scattered through the electropherogram. The same homogenate was digested using trypsin, and then labeled and subjected to the 2-D separation. In this case, the two ridges observed from the original 2-D separation disappeared and were replaced by a set of spots that fell along the diagonal. Those spots were identified using a local-maximum algorithm and each was fit using a 2-D Gaussian surface by an unsupervised nonlinear least squares regression algorithm. The migration times of the tryptic digest components were highly correlated (r=0.862). When the slowest migrating components were eliminated from the analysis, the correlation coefficient improved to r=0.956.
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Affiliation(s)
- Jane A Dickerson
- Department of Chemistry, University of Washington, Seattle, WA 98195-1700, USA
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16
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Kaneta T, Yamamoto D, Imasaka T. Postcolumn derivatization of proteins in capillary sieving electrophoresis/laser-induced fluorescence detection. Electrophoresis 2009; 30:3780-5. [DOI: 10.1002/elps.200900314] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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17
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Zuchner T, Schumer F, Berger-Hoffmann R, Müller K, Lukas M, Zeckert K, Marx J, Hennig H, Hoffmann R. Highly Sensitive Protein Detection Based on Lanthanide Chelates with Antenna Ligands Providing a Linear Range of Five Orders of Magnitude. Anal Chem 2009; 81:9449-53. [DOI: 10.1021/ac902175g] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Thole Zuchner
- Institute of Bioanalytical Chemistry, Center of Biotechnology and Biomedicine, Faculty of Chemistry and Mineralogy, Leipzig University, Deutscher Platz 5, 04103 Leipzig, Germany, XynTec Chemie GmbH Wolfen, ChemiePark Bitterfeld Andresenstrasse 1a, D-06766 Wolfen, Germany, and Institute of Inorganic Chemistry, Faculty of Chemistry and Mineralogy, Leipzig University, Johannisallee 29, 04103 Leipzig, Germany
| | - Frank Schumer
- Institute of Bioanalytical Chemistry, Center of Biotechnology and Biomedicine, Faculty of Chemistry and Mineralogy, Leipzig University, Deutscher Platz 5, 04103 Leipzig, Germany, XynTec Chemie GmbH Wolfen, ChemiePark Bitterfeld Andresenstrasse 1a, D-06766 Wolfen, Germany, and Institute of Inorganic Chemistry, Faculty of Chemistry and Mineralogy, Leipzig University, Johannisallee 29, 04103 Leipzig, Germany
| | - Renate Berger-Hoffmann
- Institute of Bioanalytical Chemistry, Center of Biotechnology and Biomedicine, Faculty of Chemistry and Mineralogy, Leipzig University, Deutscher Platz 5, 04103 Leipzig, Germany, XynTec Chemie GmbH Wolfen, ChemiePark Bitterfeld Andresenstrasse 1a, D-06766 Wolfen, Germany, and Institute of Inorganic Chemistry, Faculty of Chemistry and Mineralogy, Leipzig University, Johannisallee 29, 04103 Leipzig, Germany
| | - Katrin Müller
- Institute of Bioanalytical Chemistry, Center of Biotechnology and Biomedicine, Faculty of Chemistry and Mineralogy, Leipzig University, Deutscher Platz 5, 04103 Leipzig, Germany, XynTec Chemie GmbH Wolfen, ChemiePark Bitterfeld Andresenstrasse 1a, D-06766 Wolfen, Germany, and Institute of Inorganic Chemistry, Faculty of Chemistry and Mineralogy, Leipzig University, Johannisallee 29, 04103 Leipzig, Germany
| | - Mathias Lukas
- Institute of Bioanalytical Chemistry, Center of Biotechnology and Biomedicine, Faculty of Chemistry and Mineralogy, Leipzig University, Deutscher Platz 5, 04103 Leipzig, Germany, XynTec Chemie GmbH Wolfen, ChemiePark Bitterfeld Andresenstrasse 1a, D-06766 Wolfen, Germany, and Institute of Inorganic Chemistry, Faculty of Chemistry and Mineralogy, Leipzig University, Johannisallee 29, 04103 Leipzig, Germany
| | - Kornelia Zeckert
- Institute of Bioanalytical Chemistry, Center of Biotechnology and Biomedicine, Faculty of Chemistry and Mineralogy, Leipzig University, Deutscher Platz 5, 04103 Leipzig, Germany, XynTec Chemie GmbH Wolfen, ChemiePark Bitterfeld Andresenstrasse 1a, D-06766 Wolfen, Germany, and Institute of Inorganic Chemistry, Faculty of Chemistry and Mineralogy, Leipzig University, Johannisallee 29, 04103 Leipzig, Germany
| | - Jörg Marx
- Institute of Bioanalytical Chemistry, Center of Biotechnology and Biomedicine, Faculty of Chemistry and Mineralogy, Leipzig University, Deutscher Platz 5, 04103 Leipzig, Germany, XynTec Chemie GmbH Wolfen, ChemiePark Bitterfeld Andresenstrasse 1a, D-06766 Wolfen, Germany, and Institute of Inorganic Chemistry, Faculty of Chemistry and Mineralogy, Leipzig University, Johannisallee 29, 04103 Leipzig, Germany
| | - Horst Hennig
- Institute of Bioanalytical Chemistry, Center of Biotechnology and Biomedicine, Faculty of Chemistry and Mineralogy, Leipzig University, Deutscher Platz 5, 04103 Leipzig, Germany, XynTec Chemie GmbH Wolfen, ChemiePark Bitterfeld Andresenstrasse 1a, D-06766 Wolfen, Germany, and Institute of Inorganic Chemistry, Faculty of Chemistry and Mineralogy, Leipzig University, Johannisallee 29, 04103 Leipzig, Germany
| | - Ralf Hoffmann
- Institute of Bioanalytical Chemistry, Center of Biotechnology and Biomedicine, Faculty of Chemistry and Mineralogy, Leipzig University, Deutscher Platz 5, 04103 Leipzig, Germany, XynTec Chemie GmbH Wolfen, ChemiePark Bitterfeld Andresenstrasse 1a, D-06766 Wolfen, Germany, and Institute of Inorganic Chemistry, Faculty of Chemistry and Mineralogy, Leipzig University, Johannisallee 29, 04103 Leipzig, Germany
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18
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Moran-Mirabal JM, Corgie SC, Bolewski JC, Smith HM, Cipriany BR, Craighead HG, Walker LP. Labeling and Purification of Cellulose-Binding Proteins for High Resolution Fluorescence Applications. Anal Chem 2009; 81:7981-7. [DOI: 10.1021/ac901183b] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jose M. Moran-Mirabal
- Department of Biological and Environmental Engineering and School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14850
| | - Stephane C. Corgie
- Department of Biological and Environmental Engineering and School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14850
| | - Jacob C. Bolewski
- Department of Biological and Environmental Engineering and School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14850
| | - Hanna M. Smith
- Department of Biological and Environmental Engineering and School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14850
| | - Benjamin R. Cipriany
- Department of Biological and Environmental Engineering and School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14850
| | - Harold G. Craighead
- Department of Biological and Environmental Engineering and School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14850
| | - Larry P. Walker
- Department of Biological and Environmental Engineering and School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14850
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19
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Qiao X, Wang L, Ma J, Deng Q, Liang Z, Zhang L, Peng X, Zhang Y. High sensitivity analysis of water-soluble, cyanine dye labeled proteins by high-performance liquid chromatography with fluorescence detection. Anal Chim Acta 2009; 640:114-20. [DOI: 10.1016/j.aca.2009.03.021] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2008] [Revised: 02/14/2009] [Accepted: 03/09/2009] [Indexed: 10/21/2022]
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20
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Inoue Y, Okamoto Y, Kaji N, Tokeshi M, Baba Y. Luminescence of Cup-Stacked Carbon Nanotubes and Its Application to Microchip Electrophoresis. BUNSEKI KAGAKU 2009. [DOI: 10.2116/bunsekikagaku.58.517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Yousuke Inoue
- Department of Applied Chemistry, Graduate School of Engineering, Nagoya University
| | - Yukihiro Okamoto
- Department of Applied Chemistry, Graduate School of Engineering, Nagoya University
- MEXT Innovative Research Center for Preventive Medical Engineering, Nagoya University
| | - Noritada Kaji
- Department of Applied Chemistry, Graduate School of Engineering, Nagoya University
- MEXT Innovative Research Center for Preventive Medical Engineering, Nagoya University
| | - Manabu Tokeshi
- Department of Applied Chemistry, Graduate School of Engineering, Nagoya University
- MEXT Innovative Research Center for Preventive Medical Engineering, Nagoya University
| | - Yoshinobu Baba
- Department of Applied Chemistry, Graduate School of Engineering, Nagoya University
- MEXT Innovative Research Center for Preventive Medical Engineering, Nagoya University
- Plasma Nanotechnology Research Center, Nagoya University
- Health Technology Reseach Center, AIST
- Institute for Molecular Science
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21
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Nichols ER, Craig DB. Measurement of the differences in electrophoretic mobilities of individual molecules ofE. coliβ-galactosidase provides insight into structural differences which underlie enzyme microheterogeneity. Electrophoresis 2008; 29:4257-69. [DOI: 10.1002/elps.200800060] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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22
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Qi LY, Yin XF, Zhang L, Wang M. Rapid and variable-volume sample loading in sieving electrophoresis microchips using negative pressure combined with electrokinetic force. LAB ON A CHIP 2008; 8:1137-1144. [PMID: 18584090 DOI: 10.1039/b800085a] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
A rapid and variable-volume sample loading scheme for chip-based sieving electrophoresis was developed by negative pressure combined with electrokinetic force. This was achieved by using a low-cost microvacuum pump and a single potential supply at a constant voltage. Both 12% linear polyacrylamide (LPA) with a high viscosity of 15000 cP and 2% hydroxyethylcellulose (HEC) with a low viscosity of 102 cP were chosen as the sieving materials to study the behavior and the versatility of the proposed method. To reduce the hydrodynamic resistance in the sampling channel, sieving material was only filled in the separation channel between the buffer waste reservoir (BW) to the edge of the crossed intersection. By applying a subambient pressure to the headspace of sample waste reservoir (SW), sample and buffer solution were drawn immediately from sample reservoir (S) and buffer reservoir (B) across the intersection to SW. At the same time, the charged sample in the sample flow was driven across the interface between the sample flow and the sieving matrix into the sieving material filled separation channel by the applied electric field. The injected sample plug length is in proportion with the loading time. Once the vacuum in SW reservoir was released to activate electrophoretic separation, flows from S and B to SW were immediately terminated by the back flow induced by the difference of the liquid levels in the reservoirs to prevent sample leakage during the separation stage. The sample consumption was about 1.7 x 10(2) nL at a loading time of 1 s for each cycle. Only 0.024 s was required to transport bias-free analyte to the injection point. It is easy to freely choose the sample plug volume in this method by simply changing the loading time and to inject high quality sample plug with non-distorted shape into the separation channel. The system has been proved to possess an exciting potential for improving throughput, repeatability, sensitivity and separation performance of chip-based sieving electrophoresis.
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Affiliation(s)
- Li-Ya Qi
- Institute of Microanalytical Systems, Department of Chemistry, Zhejiang University, Hangzhou, China
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Wojcik R, Swearingen KE, Dickerson JA, Turner EH, Ramsay LM, Dovichi NJ. Reaction of fluorogenic reagents with proteins I. Mass spectrometric characterization of the reaction with 3-(2-furoyl)quinoline-2-carboxaldehyde, Chromeo P465, and Chromeo P503. J Chromatogr A 2008; 1194:243-8. [PMID: 18479688 PMCID: PMC2518533 DOI: 10.1016/j.chroma.2008.04.042] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2008] [Revised: 04/10/2008] [Accepted: 04/17/2008] [Indexed: 10/22/2022]
Abstract
3-(2-Furoyl)quinoline-2-carboxaldehyde (FQ), Chromeo P465, and Chromeo P503 are weakly fluorescent reagents that react with primary amines to produce fluorescent products. We studied the reaction of these reagents with alpha-lactalbumin by mass spectrometry. The reaction generated a set of products by the addition of one or more labels to the protein. At room temperature, the reaction was an order of magnitude faster with the Chromeo reagents than with FQ; however, the steady-state labeling efficiency was a factor of two higher for FQ compared with the Chromeo reagents. The relative abundance of the products with FQ usually followed a binomial distribution, which suggests that the labeling sites were uniformly accessible to this reagent. In contrast, the distribution of reaction products with the Chromeo reagents did not follow a binomial distribution for reactions performed in the absence of sodium dodecyl sulfate (SDS); it appears that the protein labeled with the Chromeo reagents refolded into a relatively stable secondary structure that hid some reactive sites. The reaction with the Chromeo reagent did follow the binomial distribution if the protein underwent treatment with 1% SDS at 95 degrees C for 5 min, which apparently disrupts the protein's secondary structure and allowed uniform access to all labeling sites. Chromeo 503 labeled seven of the 13 primary amines in denatured alpha-lactalbumin.
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Affiliation(s)
- Roza Wojcik
- Department of Chemistry, University of Washington, Box 351700, Seattle, WA 98195-1700, USA
| | - Kristian E. Swearingen
- Department of Chemistry, University of Washington, Box 351700, Seattle, WA 98195-1700, USA
| | - Jane A. Dickerson
- Department of Chemistry, University of Washington, Box 351700, Seattle, WA 98195-1700, USA
| | - Emily H. Turner
- Department of Chemistry, University of Washington, Box 351700, Seattle, WA 98195-1700, USA
| | - Lauren M. Ramsay
- Department of Chemistry, University of Washington, Box 351700, Seattle, WA 98195-1700, USA
| | - Norman J. Dovichi
- Department of Chemistry, University of Washington, Box 351700, Seattle, WA 98195-1700, USA
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Yin X, Zhu L, Wang M. Intracellular Labeling Methods for Chip-Based Capillary Electrophoresis. J LIQ CHROMATOGR R T 2008. [DOI: 10.1080/10826070802128698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Xuefeng Yin
- a Institute of Microanalytical Systems, Department of Chemistry, Zhejiang University , Hangzhou, P. R. China
| | - Lanlan Zhu
- a Institute of Microanalytical Systems, Department of Chemistry, Zhejiang University , Hangzhou, P. R. China
| | - Min Wang
- a Institute of Microanalytical Systems, Department of Chemistry, Zhejiang University , Hangzhou, P. R. China
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Kottegoda S, Aoto PC, Sims CE, Allbritton NL. Biarsenical-tetracysteine motif as a fluorescent tag for detection in capillary electrophoresis. Anal Chem 2008; 80:5358-66. [PMID: 18522433 DOI: 10.1021/ac8003242] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Biarsenical dyes complexed to tetracysteine motifs have proven to be highly useful fluorescent dyes in labeling specific cellular proteins for microscopic imaging. Their many advantages include membrane permeability, relatively small size, stoichiometric labeling, high affinity, and an assortment of excitation/emission wavelengths. The goal of the current study was to determine whether the biarsenical labeling scheme could be extended to fluorescent detection of analytes in capillary electrophoresis. Recombinant protein or synthesized peptides containing the optimized tetracysteine motif "-C-C-P-G-C-C-" were labeled with biarsenical dyes and then analyzed by micellar electrokinetic capillary chromatography (MEKC). The biarsenical-tetracysteine complex was stable and remained fluorescent under standard MEKC conditions for peptide and protein separations. The detection limit following electrophoresis in a capillary was less than 3 x 10(-20) mol with a simple laser-induced fluorescence system. A mixture of multiple biarsenical-labeled peptides and a protein were easily resolved. Demonstrating that the label did not interfere with bioactivity, a peptide-based enzyme substrate conjugated to the tetracysteine motif and labeled with a biarsenical dye retained its ability to be phosphorylated by the parent kinase. The feasibility of using this label for chemical cytometry experiments was shown by intracellular labeling and subsequent analysis of a recombinant protein possessing the tetracysteine motif expressed in living cells. The extension of the biarsenical-tetracysteine tag to fluorescent labeling of peptides and proteins in chemical separations is a valuable addition to biochemical and cell-based investigations.
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Affiliation(s)
- Sumith Kottegoda
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599-3290, USA
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26
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Swearingen KE, Dickerson JA, Turner EH, Ramsay LM, Wojcik R, Dovichi NJ. Reaction of fluorogenic reagents with proteins II: capillary electrophoresis and laser-induced fluorescence properties of proteins labeled with Chromeo P465. J Chromatogr A 2008; 1194:249-52. [PMID: 18479693 DOI: 10.1016/j.chroma.2008.04.047] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2008] [Revised: 04/16/2008] [Accepted: 04/18/2008] [Indexed: 11/18/2022]
Abstract
The fluorogenic reagent Chromeo P465 is considered for the analysis of proteins by capillary electrophoresis with laser-induced fluorescence detection. The reagent was first used to label alpha-lactalbumin; the product was analyzed by capillary zone electrophoresis in a sub-micellar sodium dodecyl sulfate (SDS) buffer. The product generated a set of equally spaced but poorly resolved peaks that formed a broad envelope with a net mobility of 4 x 10(-4)cm(2) V(-1) s(-1). The components of the envelope were presumably protein that had reacted with different numbers of labels. The mobility of these components decreased by roughly 1% with the addition of each label. The signal increased linearly from 1.0 nM to 100 nM alpha-lactalbumin (r(2)=0.99), with a 3sigma detection limit of 70 pM. We then considered the separation of a mixture of ovalbumin, alpha-chymotrypsinogen A, and alpha-lactalbumin labeled with Chromeo P465; unfortunately, baseline resolution was not achieved with a borax/SDS buffer. Better resolution was achieved with N-cyclohexyl-2-aminoethanesulfonic acid/Tris/SDS/dextran capillary sieving electrophoresis; however, dye interactions with this buffer system produced a less than ideal blank.
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Affiliation(s)
- Kristian E Swearingen
- Department of Chemistry, University of Washington, Box 351700, Seattle, WA 98195-1700, USA
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27
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Hubbuch J, Kula MR. Confocal laser scanning microscopy as an analytical tool in chromatographic research. Bioprocess Biosyst Eng 2008; 31:241-59. [DOI: 10.1007/s00449-008-0197-5] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2007] [Accepted: 01/02/2008] [Indexed: 11/29/2022]
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28
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Cohen D, Dickerson JA, Whitmore CD, Turner EH, Palcic MM, Hindsgaul O, Dovichi NJ. Chemical cytometry: fluorescence-based single-cell analysis. ANNUAL REVIEW OF ANALYTICAL CHEMISTRY (PALO ALTO, CALIF.) 2008; 1:165-190. [PMID: 20636078 DOI: 10.1146/annurev.anchem.1.031207.113104] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Cytometry deals with the analysis of the composition of single cells. Flow and image cytometry employ antibody-based stains to characterize a handful of components in single cells. Chemical cytometry, in contrast, employs a suite of powerful analytical tools to characterize a large number of components. Tools have been developed to characterize nucleic acids, proteins, and metabolites in single cells. Whereas nucleic acid analysis employs powerful polymerase chain reaction-based amplification techniques, protein and metabolite analysis tends to employ capillary electrophoresis separation and ultrasensitive laser-induced fluorescence detection. It is now possible to detect yoctomole amounts of many analytes in single cells.
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Affiliation(s)
- Daniella Cohen
- Department of Chemistry, University of Washington, Seattle, 98195, USA
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29
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Yu CJ, Chang HC, Tseng WL. On-line concentration of proteins by SDS-CGE with LIF detection. Electrophoresis 2008; 29:483-90. [DOI: 10.1002/elps.200700217] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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30
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Wu S, Lu JJ, Wang S, Peck KL, Li G, Liu S. Staining method for protein analysis by capillary gel electrophoresis. Anal Chem 2007; 79:7727-33. [PMID: 17874848 PMCID: PMC2753390 DOI: 10.1021/ac071055n] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A novel staining method and the associated fluorescent dye were developed for protein analysis by capillary SDS-PAGE. The method strategy is to synthesize a pseudo-SDS dye and use it to replace some of the SDS in SDS-protein complexes so that the protein can be fluorescently detected. The pseudo-SDS dye consists of a long, straight alkyl chain connected to a negative charged fluorescent head and binds to proteins just as SDS. The number of dye molecules incorporated with a protein depends on the dye concentration relative to SDS in the sample solution, since SDS and dye bind to proteins competitively. In this work, we synthesized a series of pseudo-SDS dyes, and tested their performances for capillary SDS-PAGE. FT-16 (a fluorescein molecule linked with a hexadodecyl group) seemed to be the best among all the dyes tested. Although the numbers of dye molecules bound to proteins (and the fluorescence signals from these protein complexes) were maximized in the absence of SDS, high-quality separations were obtained when co-complexes of SDS-protein-dye were formed. The migration time correlates well with protein size even after some of the SDS in the SDS-protein complexes was replaced by the pseudo-SDS dye. Under optimized experimental conditions and using a laser-induced fluorescence detector, limits of detection of as low as 0.13 ng/mL (bovine serum albumin) and dynamic ranges over 5 orders of magnitude in which fluorescence response is proportional to the square root of analyte concentration were obtained. The method and dye were also tested for separations of real-world samples from E. coli.
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Affiliation(s)
| | | | | | | | | | - Shaorong Liu
- Corresponding author. Fax: 806 742 1289, E-mail:
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31
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Oswald B, Gruber M, Böhmer M, Lehmann F, Probst M, Wolfbeis OS. Novel Diode Laser-compatible Fluorophores and Their Application to Single Molecule Detection, Protein Labeling and Fluorescence Resonance Energy Transfer Immunoassay. Photochem Photobiol 2007. [DOI: 10.1562/0031-8655(2001)0740237ndlcfa2.0.co2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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32
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Chen X, Fazal MA, Dovichi NJ. CSE-MECC two-dimensional capillary electrophoresis analysis of proteins in the mouse tumor cell (AtT-20) homogenate. Talanta 2007; 71:1981-1985. [PMID: 17637850 PMCID: PMC1920328 DOI: 10.1016/j.talanta.2006.09.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Two-dimensional capillary electrophoresis was used for the separation of proteins and biogenic amines from the mouse AtT-20 cell line. The first-dimension capillary contained a TRIS-CHES-SDS-dextran buffer to perform capillary sieving electrophoresis, which is based on molecular weight of proteins. The second-dimension capillary contained a TRIS-CHES-SDS buffer for micel1ar electrokinetic capillary chromatography. After a 61 seconds preliminary separation, fractions from the first-dimension capillary were successively transferred to the second-dimension capillary, where they further separated by MECC. The two-dimensional separation required 60 minutes.
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Affiliation(s)
- Xingguo Chen
- Department of Chemistry, University of Washington, Seattle, Washington, 98195, USA
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33
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Abstract
CE- and microchip-based separations coupled with LIF are powerful tools for the separation, detection and determination of biomolecules. CE with certain configurations has the potential to detect a small number of molecules or even a single molecule, thanks to the high spatial coherence of the laser source which permits the excitation of very small sample volumes with high efficiency. This review article discusses the use of LIF detection for the analysis of peptides and proteins in CE. The most common laser sources, basic instrumentation, derivatization modes and set-ups are briefly presented and special attention is paid to the different fluorogenic agents used for pre-, on- and postcapillary derivatization of the functional groups of these compounds. A table summarizing major applications of these derivatization reactions to the analysis of peptides and proteins in CE-LIF and a bibliography with 184 references are provided which covers papers published to the end of 2005.
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34
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Kraly JR, Jones MR, Gomez DG, Dickerson JA, Harwood MM, Eggertson M, Paulson TG, Sanchez CA, Odze R, Feng Z, Reid BJ, Dovichi NJ. Reproducible two-dimensional capillary electrophoresis analysis of Barrett's esophagus tissues. Anal Chem 2006; 78:5977-86. [PMID: 16944874 PMCID: PMC2597506 DOI: 10.1021/ac061029+] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
We have constructed a high-speed, two-dimensional capillary electrophoresis system with a compact and high-sensitivity fluorescence detector. This instrument is used for the rapid and reproducible separations of Barrett's esophagus tissue homogenates. Proteins and biogenic amines are labeled with the fluorogenic reagent 3-(2-furoyl)quinoline-2-carboxaldehyde. Labeled biomolecules are separated sequentially in two capillaries. The first capillary employs capillary sieving electrophoresis using a replaceable sieving matrix. Fractions are successively transferred to a second capillary where they undergo additional separation by micellar electrokinetic capillary chromatography. The comprehensive two-dimensional separation requires 60 min. Within-day migration time reproducibility is better than 1% in both dimensions for the 50 most intense features. Between-day migration time precision is 1.3% for CSE and better than 0.6% for MECC. Biopsies were obtained from the squamous epithelium in the proximal tubular esophagus, Barrett's epithelium from the distal esophagus, and fundus region of the stomach from each of three Barrett's esophagus patients with informed consent. We identified 18 features from the homogenate profiles as biogenic amines and amino acids. For each of the patients, Barrett's biopsies had more than 5 times the levels of phenylalanine and alanine as compared to squamous tissues. The patient with high-grade dysplasia shows the highest concentrations for 13 of the amino acids across all tissue types. Concentrations of glycine are 40 times higher in squamous biopsies compared to Barrett's and fundal biopsies from the patient with high-grade dysplasia. These results suggest that two-dimensional capillary electrophoresis may be of value for the rapid characterization of endoscopic and surgical biopsies.
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Affiliation(s)
- James R Kraly
- Department of Chemistry, University of Washington, Seattle, WA 98195-1700, USA
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35
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Edirisinghe PD, Moore JF, Calaway WF, Veryovkin IV, Pellin MJ, Hanley L. Vacuum Ultraviolet Postionization of Aromatic Groups Covalently Bound to Peptides. Anal Chem 2006; 78:5876-83. [PMID: 16906735 DOI: 10.1021/ac0605997] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Experiments demonstrate that peptides with ionization potentials (IPs) above 7.87 eV can be single-photon-ionized in the gas phase with a molecular fluorine laser following prior chemical derivatization with one of several aromatic tags acting as chromophores. 4-(Dimethylamino)benzoic acid, 1-naphthylacetic acid, and 9-anthracenecarboxylic acid (denoted Benz, Naph and Anth, respectively) behave as chromophores, allowing single-photon ionization for vacuum ultraviolet (VUV) laser light by lowering the IP of the tagged peptide. Anth-tagged peptides that are laser-desorbed from a substrate and subsequently postionized produce mass spectra dominated by the intact radical cation, although protonated ions and fragmented species are also observed. Electronic structure calculations on Anth-tagged peptides indicate that in addition to lowering the ionization potential, the presence of the aromatic tag increases charge localization on and delocalization across the ring structure, which presumably stabilizes the radical cation. Measurements on several tagged peptides confirm this calculation and show that the stabilizing effect of the tag increases with the size of the conjugated system in the order Benz < Naph < Anth. The tagged hexapeptide Anth-GAPKSC exhibits the parent ion, whereas the Benz- and Naph-tagged peptides do not. These results are supported by the experimental comparison of Anth-tagged vs untagged tryptophan, further suggesting that VUV postionization of tagged high-IP species is a promising method for expanding the capabilities of mass spectrometric analyses of molecular species.
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Affiliation(s)
- Praneeth D Edirisinghe
- Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607, USA
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36
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Stoyanov AV, Fan ZH, Das C, Ahmadzadeh H, Mei Q, Mohammed S. On the possibility of applying noncovalent dyes for protein labeling in isoelectric focusing. Anal Biochem 2006; 350:263-7. [PMID: 16460657 DOI: 10.1016/j.ab.2005.12.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2005] [Revised: 12/01/2005] [Accepted: 12/04/2005] [Indexed: 10/25/2022]
Abstract
Noncovalent fluorescent dyes are widely used for protein quantification and postcolumn detection in electrophoretic separations and recently some attempts to separate the precolumn labeled proteins using isoelectric focusing (IEF) have been made. In the present study, the possibility of applying the technique of protein labeling with noncovalent dyes for IEF is investigated. We found that fluorescent signal emitted by NanoOrange dye increases essentially in presence of carrier ampholyte (CA) components, which makes problematic a reliable protein detection in CA environment. Since in an isoelectric focusing mode the CA species are present in much greater concentration than the concentrations of fractionated proteins, the method of protein labeling with NanoOrange is not suitable for precolumn labeling and cannot be used for CA-IEF, at least without more detailed study of the dye-protein interaction mechanism.
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Veledo MT, de Frutos M, Diez-Masa JC. Amino acids determination using capillary electrophoresis with on-capillary derivatization and laser-induced fluorescence detection. J Chromatogr A 2005; 1079:335-43. [PMID: 16038320 DOI: 10.1016/j.chroma.2005.03.111] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Free amino acids have been derivatized on-capillary with 3-(2-furoyl)quinoline-2-carboxaldehyde (FQ) and analyzed using a laboratory-made capillary electrophoresis apparatus with laser-induced fluorescence detection. Several parameters that control on-capillary derivatization of amino acids, including pH, mixing time, reaction time, concentration of the derivatization reagents (potassium cyanide and FQ) and solvent of FQ, as well as the temperature of mixing and reaction were optimized. Repeatabilities better than 1.8% for migration time and 7.8% for peak height were obtained. Assay detection limits for the different amino acids ranged from 23 nM for glycine to 50 nM for lysine and glutamic acid. The methods developed were applied to the analysis of several amino acids in pharmaceutical preparations and plasma samples. Results showed a good agreement with those obtained using an amino acid autoanalyzer for the same samples.
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Affiliation(s)
- Maria Teresa Veledo
- Institute of Organic Chemistry (C.S.I.C.), Juan de la Cierva 3, 28006 Madrid, Spain
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38
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Craig DB, Wetzl BK, Duerkop A, Wolfbeis OS. Determination of picomolar concentrations of proteins using novel amino reactive chameleon labels and capillary electrophoresis laser-induced fluorescence detection. Electrophoresis 2005; 26:2208-13. [PMID: 15880625 DOI: 10.1002/elps.200410332] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Py-1 and Py-6 are novel amino-reactive fluorescent reagents. The names given to them reflect that they consist of a pyrylium group attached to small aromatic moieties. Upon reaction with a primary amine there is a large spectral shift in the reagent, rendering them effectively fluorogenic. In this study, these reagents were used to label a test protein, (human serum albumin), and the sample was analyzed by capillary electrophoresis and laser-induced fluorescence detection. Detection limits after a 60 min labeling reaction at 22 degrees C (Py-1) and 50 degrees C (Py-6) were 6.5 ng/mL (98 pM) for Py-1 and 1.2 ng/mL (18 pM) for Py-6. Separation of immunoglobulin G (IgG), human serum albumin, lipase, and myoglobin after labeling with Py-6 were performed. The method was further modified to make it amenable to automation. Unlike many other amino reactive reagents used to label protein amino groups, reaction with Py-1 and Py-6 do not alter the charge of the protein and the advantage of this with respect to electrophoretic separations is discussed.
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Affiliation(s)
- Douglas B Craig
- Institute of Analytical Chemistry, Chemo- and Biosensors, University of Regensburg, Regensburg, Germany.
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39
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Fruetel JA, Renzi RF, Vandernoot VA, Stamps J, Horn BA, West JAA, Ferko S, Crocker R, Bailey CG, Arnold D, Wiedenman B, Choi WY, Yee D, Shokair I, Hasselbrink E, Paul P, Rakestraw D, Padgen D. Microchip separations of protein biotoxins using an integrated hand-held device. Electrophoresis 2005; 26:1144-54. [PMID: 15704246 DOI: 10.1002/elps.200406194] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
We report the development of a hand-held instrument capable of performing two simultaneous microchip separations (gel and zone electrophoresis), and demonstrate this instrument for the detection of protein biotoxins. Two orthogonal analysis methods are chosen over a single method in order to improve the probability of positive identification of the biotoxin in an unknown mixture. Separations are performed on a single fused-silica wafer containing two separation channels. The chip is housed in a microfluidic manifold that utilizes o-ring sealed fittings to enable facile and reproducible fluidic connection to the chip. Sample is introduced by syringe injection into a septum-sealed port on the device exterior that connects to a sample loop etched onto the chip. Detection of low nanomolar concentrations of fluorescamine-labeled proteins is achieved using a miniaturized laser-induced fluorescence detection module employing two diode lasers, one per separation channel. Independently controlled miniature high-voltage power supplies enable fully programmable electrokinetic sample injection and analysis. As a demonstration of the portability of this instrument, we evaluated its performance in a laboratory field test at the Defence Science and Technology Laboratory with a series of biotoxin variants. The two separation methods cleanly distinguish between members of a biotoxin test set. Analysis of naturally occurring variants of ricin and two closely related staphylococcal enterotoxins indicates the two methods can be used to readily identify ricin in its different forms and can discriminate between two enterotoxin isoforms.
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Affiliation(s)
- Julia A Fruetel
- Sandia National Laboratories, P.O. Box 969, MS 9201, Livermore, CA 94551, USA.
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40
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Fluorescence detection in capillary electrophoresis. ACTA ACUST UNITED AC 2005. [DOI: 10.1016/s0166-526x(05)45006-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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41
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Edirisinghe PD, Lateef SS, Crot CA, Hanley L, Pellin MJ, Calaway WF, Moore JF. Derivatization of Surface-Bound Peptides for Mass Spectrometric Detection via Threshold Single Photon Ionization. Anal Chem 2004; 76:4267-70. [PMID: 15283559 DOI: 10.1021/ac049434t] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Chemical derivatization of peptides allows efficient F2 laser single photon ionization (SPI) of Fmoc-derivatized peptides covalently bound to surfaces. Laser desorption photoionization mass spectrometry using 337-nm pulses for desorption and 157.6-nm pulses for threshold SPI forms large ions identified as common peptide fragments bound to either Fmoc or the surface linker. Electronic structure calculations indicate the Fmoc label is behaving as an ionization tag for the entire peptide, lowering the ionization potential of the complex below the 7.87-eV photon energy. This method should allow detection of many molecular species covalently or electrostatically bound to surfaces.
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Affiliation(s)
- Praneeth D Edirisinghe
- Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607, USA
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Patonay G, Salon J, Sowell J, Strekowski L. Noncovalent labeling of biomolecules with red and near- infrared dyes. Molecules 2004; 9:40-9. [PMID: 18007410 DOI: 10.3390/90300040] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2004] [Accepted: 02/27/2004] [Indexed: 11/16/2022] Open
Abstract
Biopolymers such as proteins and nucleic acids can be labeled with a fluorescent marker to allow for their detection. Covalent labeling is achieved by the reaction of an appropriately functionalized dye marker with a reactive group on a biomolecule. The recent trend, however, is the use of noncovalent labeling that results from strong hydrophobic and/or ionic interactions between the marker and biomolecule of interest. The main advantage of noncovalent labeling is that it affects the functional activity of the biomolecule to a lesser extent. The applications of luminescent cyanine and squarylium dyes are reviewed.
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Affiliation(s)
- Gabor Patonay
- Department of Chemistry, Georgia State University, University Plaza, Atlanta, Georgia 30303, USA.
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Welder F, Paul B, Nakazumi H, Yagi S, Colyer CL. Symmetric and asymmetric squarylium dyes as noncovalent protein labels: a study by fluorimetry and capillary electrophoresis. J Chromatogr B Analyt Technol Biomed Life Sci 2003; 793:93-105. [PMID: 12880857 DOI: 10.1016/s1570-0232(03)00367-2] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Noncovalent interactions between two squarylium dyes and various model proteins have been explored. NN127 and SQ-3 are symmetric and asymmetric squarylium dyes, respectively, the fluorescence emissions of which have been shown to be enhanced upon complexation with proteins such as bovine serum albumin (BSA), human serum albumin (HSA), beta-lactoglobulin A, and trypsinogen. Although these dyes are poorly soluble in aqueous solution, they can be dissolved first in methanol followed by dilution with aqueous buffer without precipitation, and are then suitable for use as fluorescent labels in protein determination studies. The nature of interactions between these dyes and proteins was studied using a variety of buffer systems, and it was found that electrostatic interactions are involved but not dominant. Dye/protein stoichiometries in the noncovalent complexes were found to be 1:1 for SQ-3, although various possible stoichiometries were found for NN127 depending upon pH and protein. Association constants on the order of 10(5) and 10(7) were found for noncovalent complexes of SQ-3 and NN127, respectively, with HSA, indicating stronger interactions of the symmetric dye with proteins. Finally, HSA complexes with NN127 were determined by capillary electrophoresis with laser-induced fluorescence detection (CE-LIF). In particular, NN127 shows promise as a reagent capable of fluorescently labeling analyte proteins for analysis by CE-LIF without itself being significantly fluorescent under the aqueous solution conditions studied herein.
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Affiliation(s)
- Frank Welder
- Department of Chemistry, PO Box 7486, Wake Forest University, Winston-Salem, NC 27109, USA
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44
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Presley AD, Fuller KM, Arriaga EA. MitoTracker Green labeling of mitochondrial proteins and their subsequent analysis by capillary electrophoresis with laser-induced fluorescence detection. J Chromatogr B Analyt Technol Biomed Life Sci 2003; 793:141-50. [PMID: 12880861 DOI: 10.1016/s1570-0232(03)00371-4] [Citation(s) in RCA: 125] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
MitoTracker Green (MTG) is a mitochondrial-selective fluorescent label commonly used in confocal microscopy and flow cytometry. It is expected that this dye selectively accumulates in the mitochondrial matrix where it covalently binds to mitochondrial proteins by reacting with free thiol groups of cysteine residues. Here we demonstrate that MTG can be used as a protein labeling reagent that is compatible with a subsequent analysis by capillary electrophoresis with laser-induced fluorescence detection (CE-LIF). Although the MTG-labeled proteins and MTG do not seem to electrophoretically separate, an enhancement in fluorescence intensity of the product indicates that only proteins with free thiol groups are capable of reacting with MTG. In addition we propose that MTG is a partially selective label towards some mitochondrial proteins. This selectivity stems from the high MTG concentration in the mitochondrial matrix that favors alkylation of the available thiol groups in this subcellular compartment. To that effect we treated mitochondria-enriched fractions that had been prepared by differential centrifugation of an NS-1 cell lysate. This fraction was solubilized with an SDS-containing buffer and analyzed by CE-LIF. The presence of a band with fluorescence stronger than MTG alone also indicated the presence of an MTG-protein product. Confirming that MTG is labeling mitochondrial proteins was done by treating the solubilized mitochondrial fraction with 5-furoylquinoline-3-carboxaldehyde (FQ), a fluorogenic reagent that reacts with primary amino groups, and analysis by CE-LIF using two separate detection channels: 520 nm for MTG-labeled species and 635 nm for FQ-labeled species. In addition, these results indicate that MTG labels only a subset of proteins in the mitochondria-enriched fraction.
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Affiliation(s)
- Andrew D Presley
- Department of Chemistry, University of Minnesota, 207 Pleasant St SE, Minneapolis, MN 55455, USA
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Pinto D, Arriaga EA, Schoenherr RM, Chou SSH, Dovichi NJ. Kinetics and apparent activation energy of the reaction of the fluorogenic reagent 5-furoylquinoline-3-carboxaldehyde with ovalbumin. J Chromatogr B Analyt Technol Biomed Life Sci 2003; 793:107-14. [PMID: 12880858 DOI: 10.1016/s1570-0232(03)00368-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Incomplete labeling of proteins by a derivatizing reagent usually results in the formation of a large number of products, which can produce unacceptable band broadening during electrophoretic analysis. In this paper, we report on the reaction of the fluorogenic reagent 5-furoylquinoline-3-carboxaldehyde (FQ) with the lysine residues of ovalbumin. Mass spectrometry was first used to determine the distribution in the number of labels attached to the protein. At room temperature, 3.6+/-1.9 labels were attached after 30 min. The reaction rate and number of labels increased at elevated temperatures. At 65 degrees C, 6+/-2.5 labels were attached after 5 min. The apparent activation energy for this reaction is estimated as 48+/-17 kJ/mol. Based on the mass spectrometry study, the labeling reaction was assumed to consist of two steps. In the first, the protein unfolds to make lysine residues accessible. In the second, the reagents react with the epsilon -amine of the lysine residues. To test this hypothesis, submicellar capillary electrophoresis and laser-induced fluorescence were used to characterize the reaction mixture. The apparent activation energy was measured for the labeling reaction; the apparent activation energy was 57+/-12 kJ/mol for reaction performed in the separation buffer. Denaturing agents were added to the reaction mixture. The addition of 2 M thiourea with 6 M urea to the reaction resulted in a modest decrease in the apparent activation energy to 42+/-2 kJ/mol. The addition of 2.5 M or higher concentration of ethanol decreased the apparent activation energy to 32+/-2 kJ/mol. We conclude that the apparent activation energy for protein labeling is dominated by denaturation of the protein, and that the addition of suitable denaturing reagents can eliminate this contribution to the reaction chemistry.
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Affiliation(s)
- Devanand Pinto
- National Research Council of Canada, Institute for Marine Biosciences, 1411 Oxford St, Nova Scotia B3H 3Z1, Halifax, Canada
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46
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Wetzl B, Gruber M, Oswald B, Dürkop A, Weidgans B, Probst M, Wolfbeis OS. Set of fluorochromophores in the wavelength range from 450 to 700 nm and suitable for labeling proteins and amino-modified DNA. J Chromatogr B Analyt Technol Biomed Life Sci 2003; 793:83-92. [PMID: 12880856 DOI: 10.1016/s1570-0232(03)00366-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We describe the synthesis, purification, and spectral properties of new dyes and reactive labels. They absorb in the visible range between 450 and 700 nm and display analytically useful fluorescence. They were made amino-reactive by esterification with N-hydroxysuccinimide (NHS). The resulting oxysuccinimide (OSI) esters were covalently linked to the amino groups of human serum albumin (HSA) or certain DNA oligomers. Except for dyes 9 and 13, they contain one reactive group only in order to avoid cross linking of biomolecules. Labeling of amino-modified biomolecules was performed by standard protocols, and the labeled proteins and oligonucleotides were separated from the unreacted dye by gel chromatography using Sephadex G25 as the stationary phase in the case of proteins, and reversed-phase HPLC in the case of DNA oligomers. The dyes also have been used as donor-acceptor pairs in fluorescence energy transfer systems and in energy transfer cascades.
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Affiliation(s)
- Bianca Wetzl
- Institute of Analytical Chemistry, Chemo- and Biosensors, University of Regensburg, D-93040, Regensburg, Germany
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Hu S, Jiang J, Cook LM, Richards DP, Horlick L, Wong B, Dovichi NJ. Capillary sodium dodecyl sulfate-DALT electrophoresis with laser-induced fluorescence detection for size-based analysis of proteins in human colon cancer cells. Electrophoresis 2003; 23:3136-42. [PMID: 12298085 DOI: 10.1002/1522-2683(200209)23:18<3136::aid-elps3136>3.0.co;2-s] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Capillary sodium dodecyl sulfate (SDS)-DALT electrophoresis (SDS-DALT-CE) refers to CE separation of proteins based on their size; DALT is the abbreviation for Dalton, the unit used to describe molecular weight. In this work, seven proteins from 18 to 116 kDa were denatured by SDS, labeled by 3-(2-furoyl) quinoline-2-carboxaldehyde, separated by SDS-DALT-CE in polyethylene oxide sieving matrix, and detected by laser-induced fluorescence (LIF) in a sheath flow cuvette. This method was combined with detergent differential fractionation, which is a protein fractionation method using a series of detergent-containing buffers to sequentially extract protein fractions from cells, to analyze the proteins in HT29 human colon adenocarcinoma cells. In addition, on-column labeling was demonstrated for protein analysis by SDS-DALT-CE with LIF, and applied to analysis of proteins in a single HT29 cancer cell. Most proteins had molecular masses from 10 to 120 kDa. Similar protein profiles were obtained for single cells and protein extract of a large cell population.
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Affiliation(s)
- Shen Hu
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA
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López-Soto-Yarritu P, Díez-Masa JC, de Frutos M, Cifuentes A. Comparison of different capillary electrophoresis methods for analysis of recombinant erythropoietin glycoforms. J Sep Sci 2002. [DOI: 10.1002/1615-9314(20021101)25:15/17<1112::aid-jssc1112>3.0.co;2-b] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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49
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Sowell J, Strekowski L, Patonay G. DNA and protein applications of near-infrared dyes. JOURNAL OF BIOMEDICAL OPTICS 2002; 7:571-575. [PMID: 12421123 DOI: 10.1117/1.1502262] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2002] [Revised: 05/17/2002] [Accepted: 06/05/2002] [Indexed: 05/24/2023]
Abstract
The near-infrared region of the spectrum (650-1100 nm) offers distinct advantages over the traditional UV/vis region for spectroscopic measurements. In the past, the lack of commercially available equipment capable of working in the near infrared limited the utility of near-infrared techniques. However, since the advent of photodiodes and semiconductor lasers, much progress has been made in the development of near-infrared techniques. This paper discusses the use of near-infrared dyes used in DNA and protein applications.
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Affiliation(s)
- John Sowell
- Georgia State University, Department of Chemistry, University Plaza, Atlanta, Georgia 30303, USA
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50
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Jing P, Kaneta T, Imasaka T. Band broadening caused by the multiple labeling of proteins in micellar electrokinetic chromatography with diode laser-induced fluorescence detection. J Chromatogr A 2002; 959:281-7. [PMID: 12141554 DOI: 10.1016/s0021-9673(02)00357-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
When a labeling reagent is used, in the determination of proteins by capillary electrophoresis with laser-induced fluorescence detection, the multiple labeling of proteins frequently occurs, which can degrade the separation efficiency. In order to understand the influence of the multiple labeling of proteins on separation efficiency, the band broadening caused by a labeling reaction between bovine serum albumin (BSA) and a cyanine fluorescent dye (Cy5) was investigated using micellar electrokinetic chromatography in conjunction with diode laser-induced fluorometry. With the aid of an internal standard, methylene blue, the height equivalent to the theoretical plate (HETP) ratio of BSA to methylene blue was used as an indicator for band broadening under optimum separation conditions. Labeling conditions, including reaction buffer pH, reaction time, and initial concentration of Cy5 to bovine serum albumin, were found to influence the HETP ratio. The separation efficiency for the labeled protein was degraded by experimental conditions employed in the labeling, which indicates an increase in the heterogeneity of the final products.
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Affiliation(s)
- Peng Jing
- Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, Hakozaki, Fukuoka, Japan
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