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Thormann W, Mosher RA. Mobilization in two-step capillary isoelectric focusing: Concepts assessed by computer simulation. Electrophoresis 2024; 45:618-638. [PMID: 38115749 DOI: 10.1002/elps.202300218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2023] [Revised: 11/26/2023] [Accepted: 12/07/2023] [Indexed: 12/21/2023]
Abstract
The mobilization step in a two-step capillary isoelectric focusing protocol is discussed by means of dynamic computer simulation data for systems without and with spacer compounds that establish their zones at the beginning and end of the focusing column. After focusing in an electroosmosis-free environment (first step), mobilization (second step) can be induced electrophoretically, by the application of a hydrodynamic flow, or by a combination of both means. Dynamic simulations provide insight into the complexity of the various modes of electrophoretic mobilization and dispersion associated with hydrodynamic mobilization. The data are discussed together with the relevant literature.
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Affiliation(s)
- Wolfgang Thormann
- Institute for Infectious Diseases, University of Bern, Bern, Switzerland
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Takácsi-Nagy A, Kilár F, Thormann W. The effect of pH adjusted electrolytes on capillary isoelectric focusing assessed by high-resolution dynamic computer simulation. Electrophoresis 2021; 43:669-678. [PMID: 34894352 PMCID: PMC9306543 DOI: 10.1002/elps.202100367] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 12/02/2021] [Accepted: 12/03/2021] [Indexed: 11/10/2022]
Abstract
The effect of the composition of electrolytes on capillary IEF is assessed for systems with carrier ampholytes covering two pH units and with catholytes of decreased pH, anolytes of increased pH, and both electrode solutions with adjusted pH values. For electrolytes composed of formic acid as anolyte and ammonium hydroxide as catholyte, simulation is demonstrated to provide the expected IEF system in which analytes with pI values within the formed pH gradient are focused and become immobile. Addition of formic acid to the catholyte results in the formation of an isotachophoretic zone structure that migrates toward the cathode. With ammonium hydroxide added to the anolyte migration occurs toward the anode. In the two cases, all carrier components and amphoteric analytes migrate isotachophoretically as cations or anions, respectively. The data reveal that millimolar amounts of a counter ion are sufficient to convert an IEF pattern into an ITP system. With increasing amounts of the added counter ion, the overall length of the migrating zone structure shrinks, the range of the pH gradient changes, and the migration rate increases. The studied examples indicate that systems of this type reported in the literature should be classified as ITP and not IEF. When both electrolytes are titrated, a non-uniform background electrolyte composed of formic acid and ammonium hydroxide is established in which analytes migrate according to local pH and conductivity without forming IEF or ITP zone structures. Simulation data are in qualitative agreement with previously published experimental data.
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Affiliation(s)
- Anna Takácsi-Nagy
- Faculty of Pharmacy,Institute of Pharmaceutical Technology and Biopharmacy, University of Pécs, Pécs, Hungary
| | - Ferenc Kilár
- Institute of Bioanalysis, Medical School and Szentágothai Research Center, University of Pécs, Pécs, Hungary
| | - Wolfgang Thormann
- Institute for Infectious Diseases, University of Bern, Bern, Switzerland
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Thormann W, Mosher RA. Dynamic computer simulations of electrophoresis: 2010-2020. Electrophoresis 2021; 43:10-36. [PMID: 34287996 PMCID: PMC9292373 DOI: 10.1002/elps.202100191] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 07/12/2021] [Accepted: 07/15/2021] [Indexed: 02/05/2023]
Abstract
The transport of components in liquid media under the influence of an applied electric field can be described with the continuity equation. It represents a nonlinear conservation law that is based upon the balance laws of continuous transport processes and can be solved in time and space numerically. This procedure is referred to as dynamic computer simulation. Since its inception four decades ago, the state of dynamic computer simulation software and its use has progressed significantly. Dynamic models are the most versatile tools to explore the fundamentals of electrokinetic separations and provide insights into the behavior of buffer systems and sample components of all electrophoretic separation methods, including moving boundary electrophoresis, CZE, CGE, ITP, IEF, EKC, ACE, and CEC. This article is a continuation of previous reviews (Electrophoresis 2009, 30, S16–S26 and Electrophoresis 2010, 31, 726–754) and summarizes the progress and achievements made during the 2010 to 2020 time period in which some of the existing dynamic simulators were extended and new simulation packages were developed. This review presents the basics and extensions of the three most used one‐dimensional simulators, provides a survey of new one‐dimensional simulators, outlines an overview of multi‐dimensional models, and mentions models that were briefly reported in the literature. A comprehensive discussion of simulation applications and achievements of the 2010 to 2020 time period is also included.
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Affiliation(s)
- Wolfgang Thormann
- Institute for Infectious Diseases, University of Bern, Bern, Switzerland
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Thormann W, Mosher RA. Instabilities of the pH gradient in carrier ampholyte-based isoelectric focusing: Elucidation of the contributing electrokinetic processes by computer simulation. Electrophoresis 2020; 42:814-833. [PMID: 33184847 DOI: 10.1002/elps.202000269] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 10/22/2020] [Accepted: 11/05/2020] [Indexed: 11/05/2022]
Abstract
Electrokinetic processes that lead to pH gradient instabilities in carrier ampholyte-based IEF are reviewed. In addition to electroosmosis, there are four of electrophoretic nature, namely (i) the stabilizing phase with the plateau phenomenon, (ii) the gradual isotachophoretic loss of carrier ampholytes at the two column ends in presence of electrode solutions, (iii) the inequality of the mobilities of positively and negatively charged species of ampholytes, and (iv) the continuous penetration of carbonate from the catholyte into the focusing column. The impact of these factors to cathodic and anodic drifts was analyzed by simulation of carrier ampholyte-based focusing in closed and open columns. Focusing under realistic conditions within a 5 cm long capillary in which three amphoteric low molecular mass dyes were focused in a pH 3-10 gradient formed by 140 carrier ampholytes was investigated. In open columns, electroosmosis displaces the entire gradient toward the cathode or anode whereas the electrophoretic processes act bidirectionally with a transition around pH 4 (drifts for pI > 4 and pI < 4 typically toward the cathode and anode, respectively). The data illustrate that focused zones of carrier ampholytes have an electrophoretic flux and that dynamic simulation can be effectively used to assess the magnitude of each of the electrokinetic destabilizing factors and the resulting drift for a combination of these effects. Predicted drifts of focused marker dyes are compared to those observed experimentally in a setup with coated capillary and whole column optical imaging.
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Affiliation(s)
- Wolfgang Thormann
- Institute for Infectious Diseases, University of Bern, Bern, Switzerland
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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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Takácsi-Nagy A, Kilár F, Thormann W. Modeling of formation and prevention of a pure water zone in capillary isoelectric focusing with narrow pH range carrier ampholytes. Electrophoresis 2016; 38:677-688. [PMID: 27699824 DOI: 10.1002/elps.201600314] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 09/01/2016] [Accepted: 09/02/2016] [Indexed: 11/07/2022]
Abstract
This paper comprises a continuation of computer simulation studies dealing with carrier ampholyte based CIEF in presence of narrow pH gradients. With this technique, amphoteric sample components with pI values outside the pH gradient are migrating isotachophoretically toward the cathode or anode whereas components with pI values within the gradient become focused. In order to understand the processes occurring in presence of the electric field, the behavior of both carrier ampholytes and amphoteric sample components is investigated by computer modeling. Characteristics of two pH unit gradients with end components having pI values at or around 7.00 and conditions that lead to the formation of a water zone at neutrality were investigated. Data obtained reveal that a zone of water is formed in focusing with carrier ampholytes when the applied pH range does not cover the neutral region, ends at pH 7.00 or begins at pH 7.00. The presence of additional amphoteric components that cover the neutrality region prevent water zone formation under current flow. This situation is met in experiments with narrow pH gradients that end or begin around neutrality. Simulation data reveal that no water zone evolves when atmospheric carbon dioxide dissolved in the catholyte causes the migration of carbonic acid (in the form of carbonate and/or hydrogen carbonate ions) from the catholyte through the focusing structure. An electrolyte change in the electrode solution does not have an impact on the focusing part but does change the isotachophoretic pattern migrating behind the leading ion.
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Affiliation(s)
- Anna Takácsi-Nagy
- Institute of Bioanalysis and Szentágothai Research Center, University of Pécs, Pécs, Hungary
| | - Ferenc Kilár
- Institute of Bioanalysis and Szentágothai Research Center, University of Pécs, Pécs, Hungary
| | - Wolfgang Thormann
- Clinical Pharmacology Laboratory, Institute for Infectious Diseases, University of Bern, Bern, Switzerland
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Mikkonen S, Thormann W, Emmer Å. Computer simulations of sample preconcentration in carrier-free systems and isoelectric focusing in microchannels using simple ampholytes. Electrophoresis 2015; 36:2386-95. [PMID: 26036978 DOI: 10.1002/elps.201500120] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Revised: 04/27/2015] [Accepted: 05/12/2015] [Indexed: 01/05/2023]
Abstract
In this work, electrophoretic preconcentration of protein and peptide samples in microchannels was studied theoretically using the 1D dynamic simulator GENTRANS, and experimentally combined with MS. In all configurations studied, the sample was uniformly distributed throughout the channel before power application, and driving electrodes were used as microchannel ends. In the first part, previously obtained experimental results from carrier-free systems are compared to simulation results, and the effects of atmospheric carbon dioxide and impurities in the sample solution are examined. Simulation provided insight into the dynamics of the transport of all components under the applied electric field and revealed the formation of a pure water zone in the channel center. In the second part, the use of an IEF procedure with simple well defined amphoteric carrier components, i.e. amino acids, for concentration and fractionation of peptides was investigated. By performing simulations a qualitative description of the analyte behavior in this system was obtained. Neurotensin and [Glu1]-Fibrinopeptide B were separated by IEF in microchannels featuring a liquid lid for simple sample handling and placement of the driving electrodes. Component distributions in the channel were detected using MALDI- and nano-ESI-MS and data were in agreement with those obtained by simulation. Dynamic simulations are demonstrated to represent an effective tool to investigate the electrophoretic behavior of all components in the microchannel.
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Affiliation(s)
- Saara Mikkonen
- Department of Chemistry, Analytical Chemistry, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Wolfgang Thormann
- Clinical Pharmacology Laboratory, Institute for Infectious Diseases, University of Bern, Bern, Switzerland
| | - Åsa Emmer
- Department of Chemistry, Analytical Chemistry, KTH Royal Institute of Technology, Stockholm, Sweden
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Pirmoradian M, Zhang B, Chingin K, Astorga-Wells J, Zubarev RA. Membrane-Assisted Isoelectric Focusing Device As a Micropreparative Fractionator for Two-Dimensional Shotgun Proteomics. Anal Chem 2014; 86:5728-32. [DOI: 10.1021/ac404180e] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Mohammad Pirmoradian
- Department
of Medical Biochemistry and Biophysics, Karolinska Institutet, Scheelesväg 2, SE-17177 Stockholm, Sweden
- Biomotif AB, Stockholm, Sweden
| | - Bo Zhang
- Department
of Medical Biochemistry and Biophysics, Karolinska Institutet, Scheelesväg 2, SE-17177 Stockholm, Sweden
| | - Konstantin Chingin
- Department
of Medical Biochemistry and Biophysics, Karolinska Institutet, Scheelesväg 2, SE-17177 Stockholm, Sweden
| | - Juan Astorga-Wells
- Department
of Medical Biochemistry and Biophysics, Karolinska Institutet, Scheelesväg 2, SE-17177 Stockholm, Sweden
- Biomotif AB, Stockholm, Sweden
| | - Roman A. Zubarev
- Department
of Medical Biochemistry and Biophysics, Karolinska Institutet, Scheelesväg 2, SE-17177 Stockholm, Sweden
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Thormann W, Kilár F. High-resolution dynamic computer simulation analysis of the behavior of sample components with pIvalues outside the pH gradient established by carrier ampholyte CIEF. Electrophoresis 2013; 34:716-24. [DOI: 10.1002/elps.201200499] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Revised: 10/26/2012] [Accepted: 10/30/2012] [Indexed: 01/30/2023]
Affiliation(s)
- Wolfgang Thormann
- Clinical Pharmacology Laboratory; Institute for Infectious Diseases; University of Bern; Bern; Switzerland
| | - Ferenc Kilár
- Institute of Bioanalysis; Faculty of Medicine; University of Pécs; Pécs; Hungary
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Righetti PG, Sebastiano R, Citterio A. Capillary electrophoresis and isoelectric focusing in peptide and protein analysis. Proteomics 2012. [DOI: 10.1002/pmic.201200378] [Citation(s) in RCA: 134] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
| | - Roberto Sebastiano
- Department of Chemistry, Materials and Chemical Engineering “Giulio Natta”; Politecnico di Milano; Milano; Italy
| | - Attilio Citterio
- Department of Chemistry, Materials and Chemical Engineering “Giulio Natta”; Politecnico di Milano; Milano; Italy
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