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Krebs F, Zagst H, Stein M, Ratih R, Minkner R, Olabi M, Hartung S, Scheller C, Lapizco-Encinas BH, Sänger-van de Griend C, García CD, Wätzig H. Strategies for capillary electrophoresis: Method development and validation for pharmaceutical and biological applications-Updated and completely revised edition. Electrophoresis 2023; 44:1279-1341. [PMID: 37537327 DOI: 10.1002/elps.202300158] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Accepted: 07/19/2023] [Indexed: 08/05/2023]
Abstract
This review is in support of the development of selective, precise, fast, and validated capillary electrophoresis (CE) methods. It follows up a similar article from 1998, Wätzig H, Degenhardt M, Kunkel A. "Strategies for capillary electrophoresis: method development and validation for pharmaceutical and biological applications," pointing out which fundamentals are still valid and at the same time showing the enormous achievements in the last 25 years. The structures of both reviews are widely similar, in order to facilitate their simultaneous use. Focusing on pharmaceutical and biological applications, the successful use of CE is now demonstrated by more than 600 carefully selected references. Many of those are recent reviews; therefore, a significant overview about the field is provided. There are extra sections about sample pretreatment related to CE and microchip CE, and a completely revised section about method development for protein analytes and biomolecules in general. The general strategies for method development are summed up with regard to selectivity, efficiency, precision, analysis time, limit of detection, sample pretreatment requirements, and validation.
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Affiliation(s)
- Finja Krebs
- Institute, of Medicinal and Pharmaceutical Chemistry, Technische Universität Braunschweig, Braunschweig, Lower Saxony, Germany
| | - Holger Zagst
- Institute, of Medicinal and Pharmaceutical Chemistry, Technische Universität Braunschweig, Braunschweig, Lower Saxony, Germany
| | - Matthias Stein
- Institute, of Medicinal and Pharmaceutical Chemistry, Technische Universität Braunschweig, Braunschweig, Lower Saxony, Germany
| | - Ratih Ratih
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Surabaya, Surabaya, East Java, Indonesia
| | - Robert Minkner
- Institute, of Medicinal and Pharmaceutical Chemistry, Technische Universität Braunschweig, Braunschweig, Lower Saxony, Germany
| | - Mais Olabi
- Institute, of Medicinal and Pharmaceutical Chemistry, Technische Universität Braunschweig, Braunschweig, Lower Saxony, Germany
| | - Sophie Hartung
- Institute, of Medicinal and Pharmaceutical Chemistry, Technische Universität Braunschweig, Braunschweig, Lower Saxony, Germany
| | - Christin Scheller
- Institute, of Medicinal and Pharmaceutical Chemistry, Technische Universität Braunschweig, Braunschweig, Lower Saxony, Germany
| | - Blanca H Lapizco-Encinas
- Department of Biomedical Engineering, Kate Gleason College of Engineering, Rochester Institute of Technology, Rochester, New York, USA
| | - Cari Sänger-van de Griend
- Kantisto BV, Baarn, The Netherlands
- Department of Medicinal Chemistry, Faculty of Pharmacy, Uppsala Universitet, Uppsala, Sweden
| | - Carlos D García
- Department of Chemistry, Clemson University, Clemson, South Carolina, USA
| | - Hermann Wätzig
- Institute, of Medicinal and Pharmaceutical Chemistry, Technische Universität Braunschweig, Braunschweig, Lower Saxony, Germany
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Páger C, Biherczová N, Ligetvári R, Berkics BV, Pongrácz T, Sándor V, Bufa A, Poór V, Vojs Staňová A, Kilár F. Advanced online mass spectrometry detection of proteins separated by capillary isoelectric focusing after sequential injection. J Sep Sci 2017; 40:4825-4834. [DOI: 10.1002/jssc.201700695] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Revised: 10/02/2017] [Accepted: 10/06/2017] [Indexed: 11/06/2022]
Affiliation(s)
- Csilla Páger
- Institute of Bioanalysis and Szentágothai Research Center; University of Pécs; Pécs Hungary
| | - Nikoleta Biherczová
- Department of Analytical Chemistry; Faculty of Natural Sciences; Comenius University in Bratislava; Bratislava Slovak Republic
| | - Roland Ligetvári
- Institute of Bioanalysis and Szentágothai Research Center; University of Pécs; Pécs Hungary
| | - Balázs Viktor Berkics
- Institute of Bioanalysis and Szentágothai Research Center; University of Pécs; Pécs Hungary
| | - Tamás Pongrácz
- Institute of Bioanalysis and Szentágothai Research Center; University of Pécs; Pécs Hungary
| | - Viktor Sándor
- Institute of Bioanalysis and Szentágothai Research Center; University of Pécs; Pécs Hungary
| | - Anita Bufa
- Institute of Bioanalysis and Szentágothai Research Center; University of Pécs; Pécs Hungary
| | - Viktória Poór
- Institute of Bioanalysis and Szentágothai Research Center; University of Pécs; Pécs Hungary
| | - Andrea Vojs Staňová
- Department of Analytical Chemistry; Faculty of Natural Sciences; Comenius University in Bratislava; Bratislava Slovak Republic
- University of South Bohemia in Ceske Budejovice; Faculty of Fisheries and Protection of Waters; South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses; Vodnany Czech Republic
| | - Ferenc Kilár
- Institute of Bioanalysis and Szentágothai Research Center; University of Pécs; Pécs Hungary
- Department of Analytical and Environmental Chemistry; Faculty of Sciences; University of Pécs; Pécs Hungary
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Millioni R, Franchin C, Tessari P, Polati R, Cecconi D, Arrigoni G. Pros and cons of peptide isolectric focusing in shotgun proteomics. J Chromatogr A 2013; 1293:1-9. [PMID: 23639126 DOI: 10.1016/j.chroma.2013.03.073] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2012] [Revised: 03/27/2013] [Accepted: 03/28/2013] [Indexed: 02/03/2023]
Abstract
In shotgun proteomics, protein mixtures are proteolytically digested before tandem mass spectrometry (MS/MS) analysis. Biological samples are generally characterized by a very high complexity, therefore a step of peptides fractionation before the MS analysis is essential. This passage reduces the sample complexity and increases its compatibility with the sampling performance of the instrument. Among all the existing approaches for peptide fractionation, isoelectric focusing has several peculiarities that are theoretically known but practically rarely exploited by the proteomics community. The main aim of this review is to draw the readers' attention to these unique qualities, which are not accessible with other common approaches, and that represent important tools to increase confidence in the identification of proteins and some post-translational modifications. The general characteristics of different methods to perform peptide isoelectric focusing with natural and artificial pH gradients, the existing instrumentation, and the informatics tools available for isoelectric point calculation are also critically described. Finally, we give some general conclusions on this strategy, underlying its principal limitations.
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Affiliation(s)
- Renato Millioni
- Department of Medicine, University of Padova, Via Giustiniani 2, 35121 Padova, Italy; Proteomics Center of Padova University, VIMM and Padova University Hospital, Via G. Orus 2/B, 35129 Padova, Italy.
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Páger C, Vargová A, Takácsi-Nagy A, Dörnyei Á, Kilár F. Effect of electrolyte pH on CIEF with narrow pH range ampholytes. Electrophoresis 2012; 33:3269-75. [DOI: 10.1002/elps.201200175] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2012] [Revised: 07/05/2012] [Accepted: 07/23/2012] [Indexed: 01/19/2023]
Affiliation(s)
- Csilla Páger
- Institute of Bioanalysis; Faculty of Medicine; University of Pécs; Pécs; Hungary
| | - Andrea Vargová
- Department of Analytical and Environmental Chemistry; Faculty of Sciences; University of Pécs; Pécs; Hungary
| | - Anna Takácsi-Nagy
- Institute of Bioanalysis; Faculty of Medicine; University of Pécs; Pécs; Hungary
| | - Ágnes Dörnyei
- Institute of Bioanalysis; Faculty of Medicine; University of Pécs; Pécs; Hungary
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Köster J, Hayen H, von Wirén N, Weber G. Isoelectric focusing of small non-covalent metal species from plants. Electrophoresis 2010; 32:772-81. [PMID: 21192102 DOI: 10.1002/elps.201000529] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2010] [Revised: 11/08/2010] [Accepted: 11/09/2010] [Indexed: 12/12/2022]
Abstract
IEF is known as a powerful electrophoretic separation technique for amphoteric molecules, in particular for proteins. The objective of the present work is to prove the suitability of IEF also for the separation of small, non-covalent metal species. Investigations are performed with copper-glutathione complexes, with the synthetic ligand ethylenediamine-N,N'-bis(o-hydroxyphenyl)acetic acid (EDDHA) and respective metal complexes (Fe, Ga, Al, Ni, Zn), and with the phytosiderophore 2'-deoxymugineic acid (DMA) and its ferric complex. It is shown that ethylenediamine-N,N'-bis(o-hydroxyphenyl)acetic acid and DMA species are stable during preparative scale IEF, whereas copper-glutathione dissociates considerably. It is also shown that preparative scale IEF can be applied successfully to isolate ferric DMA from real plant samples, and that multidimensional separations are possible by combining preparative scale IEF with subsequent HPLC-MS analysis. Focusing of free ligands and respective metal complexes with di- and trivalent metals results in different pIs, but CIEF is usually needed for a reliable estimation of pI values. Limitations of the proposed methods (preparative IEF and CIEF) and consequences of the results with respect to metal speciation in plants are discussed.
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Affiliation(s)
- Jessica Köster
- Leibniz-Institut für Analytische Wissenschaften, ISAS, Dortmund, Germany
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Separation and quantitation of milk whey proteins of close isoelectric points by on-line capillary isoelectric focusing—Electrospray ionization mass spectrometry in glycerol–water media. J Chromatogr A 2010; 1217:7293-301. [DOI: 10.1016/j.chroma.2010.09.043] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2010] [Revised: 09/08/2010] [Accepted: 09/14/2010] [Indexed: 12/28/2022]
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Ramsay LM, Dickerson JA, Dada O, Dovichi NJ. Femtomolar concentration detection limit and zeptomole mass detection limit for protein separation by capillary isoelectric focusing and laser-induced fluorescence detection. Anal Chem 2010; 81:1741-6. [PMID: 19206532 DOI: 10.1021/ac8025948] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Fluorescence tends to produce the lowest detection limits for most forms of capillary electrophoresis. Two issues have discouraged its use in capillary isoelectric focusing. The first issue is fluorescent labeling of proteins. Most labeling reagents react with lysine residues and convert the cationic residue to a neutral or anionic product. At best, these reagents perturb the isoelectric point of the protein. At worse, they convert each protein into hundreds of different fluorescent products that confound analysis. The second issue is the large background signal generated by impurities within commercial ampholytes. This background signal is particularly strong when excited in the blue portion of the spectrum, which is required by many common fluorescent labeling reagents. This paper addresses these issues. For labeling, we employ Chromeo P540, which is a fluorogenic reagent that converts cationic lysine residues to cationic fluorescent products. The reaction products are excited in the green, which reduces the background signal generated by impurities present within the ampholytes. To further reduce the background signal, we photobleach ampholytes with high-power photodiodes. Photobleaching reduced the noise in the ampholyte blank by an order of magnitude. Isoelectric focusing performed with photobleached pH 3-10 ampholytes produced concentration detection limits of 270 +/- 25 fM and mass detection limits of 150 +/- 15 zmol for Chromeo P540 labeled beta-lactoglobulin. Concentration detection limits were 520 +/- 40 fM and mass detection limits were 310 +/- 30 zmol with pH 4-8 ampholytes. A homogenate was prepared from a Barrett's esophagus cell line and separated by capillary isoelectric focusing, reproducibly generating dozens of peaks. The sample taken for the separation was equal to the labeled protein homogenate from three cells.
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Affiliation(s)
- Lauren M Ramsay
- Department of Chemistry, University of Washington, Seattle, Washington 98195, USA
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Zilberstein G, Bukshpan S, Righetti PG. Third generation of focusing: gel matrices with immobilized cation gradients. Electrophoresis 2010; 31:1747-53. [PMID: 20446287 DOI: 10.1002/elps.200900602] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
A novel method is reviewed here for separation of polyanions, based not on conventional zone electrophoretic means, but on a "steady-state" process by which said polyanions are driven to stationary zones along the migration path against a gradient of positive charges affixed to the neutral polyacrylamide matrix. As the total negative surface charge of such polyanions matches the surrounding charge density of the matrix, they stop migrating and remain stationary, as typical of steady-state separation techniques. This technique has been successfully applied to SDS-protein micelles, DNAs, RNAs and heparins, with remarkable separations, often much superior than those obtained in conventional techniques. Additionally, by exploiting constant plateaus of charges, rather than gradients, it is possible to amplify the separation between species having closely spaced charge densities. This technique resembles a classical IEF process, with the proviso that the polyanions cannot be applied at any position along the gel matrix, but only at the point of low (or zero) charge density. The merits and limits of the technique are assessed.
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11
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Recent developments in capillary isoelectric focusing. J Chromatogr A 2008; 1204:157-70. [DOI: 10.1016/j.chroma.2008.05.057] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2008] [Revised: 04/30/2008] [Accepted: 05/08/2008] [Indexed: 12/22/2022]
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Silvertand LHH, Toraño JS, de Jong GJ, van Bennekom WP. Improved repeatability and matrix-assisted desorption/ionization – time of flight mass spectrometry compatibility in capillary isoelectric focusing. Electrophoresis 2008; 29:1985-96. [DOI: 10.1002/elps.200700434] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Mosher RA, Thormann W. High-resolution computer simulation of the dynamics of isoelectric focusing: In quest of more realistic input parameters for carrier ampholytes. Electrophoresis 2008; 29:1036-47. [DOI: 10.1002/elps.200700453] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Busnel JM, Le Saux T, Descroix S, Girault HH, Hennion MC, Terabe S, Peltre G. Integration of various stacking processes in carrier ampholyte-based capillary electrophoresis. J Chromatogr A 2008; 1182:226-32. [DOI: 10.1016/j.chroma.2007.12.079] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2007] [Revised: 12/10/2007] [Accepted: 12/27/2007] [Indexed: 11/16/2022]
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Righetti PG, Simó C, Sebastiano R, Citterio A. Carrier ampholytes for IEF, on their fortieth anniversary (1967–2007), brought to trial in court: The verdict. Electrophoresis 2007; 28:3799-810. [DOI: 10.1002/elps.200700232] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Simó C, Citterio A, Righetti PG. Mass distribution, polydispersity, and focusing properties of carrier ampholytes for IEF. Part V: pH 9-11 interval. Electrophoresis 2007; 28:3156-62. [PMID: 17854119 DOI: 10.1002/elps.200700123] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
As a last part of an investigation on all 2-pH-unit intervals of carrier ampholytes (CAs) for IEF (see Electrophoresis 2006, 27, 3919-3934; 2006, 27, 4849-4858; 2007, 28, 715-723) two different lots of Servalyt CAs, in the pH 9-11 range, have been analyzed by a 2-D technique based on preparative Rotofor fractionation followed by capillary electrophoresis mass-spectrometry of 10 out of 20 fractions harvested, in the second dimension. The findings: the two lots contain 65 and 69 different M(r) compounds, in the M(r) interval of 232-667 Da, for a total of 341-387 isoforms, respectively. Since this is a chaotic organic synthesis, the high reproducibility (here demonstrated for the first time during the 40 years of existence of CAs) of the synthetic process (for two batches produced at 6 years of distance) is remarkable, considering that a 94% agreement for the individual chemicals and 88% agreement for the total number of isoforms for the two lots is found. It is additionally demonstrated that the lower pI species are accompanied by considerably more isoforms than the high pI forms and that in all cases such isoforms consist of family of compounds clustered around the pI of the parental form, with a pI spread of ca. 0.1-0.2 pH units.
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Affiliation(s)
- Carolina Simó
- Department of Chemistry, Politecnico di Milano, Materials and Engineering Chemistry Giulio Natta, Milano, Italy
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Simó C, Citterio A, Righetti PG. Mass distribution, polydispersity and focusing properties of carrier ampholytes for IEF. IV: pH 6–8 intervals. Electrophoresis 2007; 28:1488-94. [PMID: 17492726 DOI: 10.1002/elps.200600853] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Four commercial brands of carrier ampholytes (Ampholine, Pharmalyte, Servalyt, Bio-Lyte), in the pH 6-8 range, have been analyzed by a 2-D technique based on preparative Rotofor fractionation followed by CE-MS of 10 out of 20 fractions harvested, in the second dimension. The findings: Ampholine (pH 6-8) contains 80 different M(r) compounds, in the M(r) interval 216-979 Da, for a total of 326 isoforms. Bio-Lyte (pH 6-8) consists of 62 different M(r) species, in the M(r) range 341-1048 Da, for a total of 237 isoforms. Servalyt (pH 6-8) is made of 126 different M(r) compounds, in the M(r) interval 240-785 Da, for a total of 703 isoforms. Pharmalyte (pH 5-8) comprises 123 amphoteres, in the M(r) range of 221-992 Da, for a total of 476 isoforms. Pharmalyte appears to be the best brand, with a good proportion of species focusing sharply at their pI position and relatively few 'poor' species, distributed along the entire pH gradient. General conclusions are drawn on the properties of all the pH intervals explored in this series of investigations and some guidelines for possible synthetic routes ameliorating the neutral and alkaline pH intervals are discussed.
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Affiliation(s)
- Carolina Simó
- Politecnico di Milano, Department of Chemistry, Materials and Engineering Chemistry Giulio Natta, Milano, Italy
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Simó C, Mendieta ME, Antonioli P, Sebastiano R, Citterio A, Cifuentes A, Righetti PG. Mass distribution, polydispersity and focusing properties of carrier ampholytes for IEF. III: pH 2.5–4 intervals. Electrophoresis 2007; 28:715-23. [PMID: 17274102 DOI: 10.1002/elps.200600499] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
To study the molecular mass distribution and number of species in narrow-range (2-pH-unit wide, in the nominal pI 2-4 or 3-5 interval) carrier ampholytes from four commercial sources (Bio-Lyte, Servalyt, Ampholine and Pharmalyte), a 2-D technique was adopted, consisting of a preparative focusing step in a Rotofor instrument, followed by analysis of every other collected fraction (10 out of 20) by CE-MS. It was found that Ampholine pH 3.5-5 contains 105 different molecular mass (M(r)) compounds, in the M(r) interval 205-965 Da, for a total of 446 isoforms. Bio-Lyte pH 3-5 consists of 84 different M(r) species, in the M(r) range 216-965 Da, for a total of 383 isoforms. Servalyt pH 2-4 is made of 227 different M(r) compounds, in the M(r) interval 204-929 Da, for a total of 1201 isoforms. Pharmalyte pH 2.5-5 comprises 245 amphoteres, in the M(r) range 203-857 Da, for a total of 857 isoforms. Pharmalyte appears to be the best brand, with the vast majority of species focusing sharply at their pI position and almost no 'poor' species, distributed along the entire pH gradient, denoting an extremely shallow pH/mobility curve across the pI value. Due to some overlap with the adjacent acidic pH 4-6 interval, the species in common have been evaluated: the most extended overlaps are found in Ampholine (55% of the species appearing in the two neighbouring intervals) and in Servalyt (47% coincidence). The lowest overlaps are found in Pharmalyte (23%) and in Bio-Lyte (20%).
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Affiliation(s)
- Carolina Simó
- Politecnico di Milano, Department of Chemistry, Materials and Engineering Chemistry Giulio Natta, Milano, Italy
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Poitevin M, Morin A, Busnel JM, Descroix S, Hennion MC, Peltre G. Comparison of different capillary isoelectric focusing methods--use of "narrow pH cuts" of carrier ampholytes as original tools to improve resolution. J Chromatogr A 2007; 1155:230-6. [PMID: 17335834 DOI: 10.1016/j.chroma.2007.02.013] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2006] [Revised: 12/21/2006] [Accepted: 02/05/2007] [Indexed: 10/23/2022]
Abstract
Two capillary isoelectric focusing (CIEF) systems have first been optimized: one uses a bare silica capillary and 30% (v/v) of glycerol in the separation medium while the other uses a coated capillary and an aqueous background electrolyte. To perform permanent capillary coating, two neutral polymers have been compared: hydroxypropylcellulose (HPC) and polyvinylalcohol (PVA). HPC coating gave best results for electroosmotic flow (EOF) limitation on a wide pH range: as compared to a bare silica capillary, it allowed to decrease EOF by 96% at pH 7.2 after acidic and basic treatments, whereas PVA coating lead only to a 76% decrease. The glycerol CIEF system was more satisfying for the separation of model proteins classically used as pI markers. Finally, the use of "narrow pH cuts" of carrier ampholytes added to commercial ampholyte mixtures allowed increasing resolution up to a factor 2.4 at a chosen pH for the separation of pI markers and milk proteins.
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Affiliation(s)
- Martine Poitevin
- Laboratory of Environment and Analytical Chemistry, UMR CNRS 7121, ESPCI, 10 rue Vauquelin, 75231 Paris Cedex 05, France
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