1
|
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.
Collapse
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
| |
Collapse
|
2
|
Li X, Shi X, Qin X, Yu L, Zhou Y, Rao C. Interlaboratory method validation of imaged capillary isoelectric focusing methodology for analysis of recombinant human erythropoietin. ANALYTICAL METHODS : ADVANCING METHODS AND APPLICATIONS 2020; 12:3836-3843. [PMID: 32678383 DOI: 10.1039/d0ay00823k] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Recombinant human erythropoietin (rhEPO) is one of the most important biopharmaceuticals worldwide, with global sales expected to reach US$11.9 billion in 2020. The charge heterogeneity of rhEPO must be monitored throughout the entire production process. Imaged capillary isoelectric focusing (icIEF) is a promising method for monitoring rhEPO charge heterogeneity, but it must be validated according to the ICH guideline (International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use). Here, a multi-laboratory joint method validation of the icIEF method for rhEPO analysis was performed according to the ICH Harmonized Tripartite Guideline on Analysis Procedure. This guideline includes specificity, precision, accuracy, linearity, range, LOQ and robustness, whereby precision is defined by the repeatability, intermediate precision and reproducibility.
Collapse
Affiliation(s)
- Xiang Li
- Key Laboratory of the Ministry of Health for Research on Quality and Standardization of Biotech Products, National Institutes for Food and Drug Control, No. 2, Tiantan Xili, Dongcheng District, Beijing, 100050, China.
| | | | | | | | | | | |
Collapse
|
3
|
Zarabadi AS, Huang T, Mielke JG. Capillary isoelectric focusing with whole column imaging detection (iCIEF): A new approach to the characterization and quantification of salivary α-amylase. J Chromatogr B Analyt Technol Biomed Life Sci 2017; 1053:65-71. [PMID: 28411466 DOI: 10.1016/j.jchromb.2017.03.032] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Revised: 02/28/2017] [Accepted: 03/27/2017] [Indexed: 11/26/2022]
Abstract
Saliva is an easily collected biological fluid with potentially important diagnostic value. While gel electrophoresis is generally used for salivary analysis, we employed the capillary isoelectric focusing technique to allow for a rapid, automated mode of electrophoresis. Capillary isoelectric focusing coupled with UV whole column imaging detection (iCIEF) was used to develop a robust protocol to characterize salivary α-amylase collected from various glands. Notably, three sample preparation methods were examined: ultrafiltration, gel-filtration, and starch affinity interaction with salivary amylase. Salivary α-amylase separated into two major peaks before sample treatment; while both filtration methods and starch affinity interaction of salivary amylase enhanced the resolution of isozymes, desalting with gel-filtration displayed the best recovery and the highest resolution of isozymes. Good agreement existed between the observed isoelectric points and the values reported in the literature. In addition, a high level of precision was apparent, and the relative standard deviation for replicates was less than 0.5% for pIs (peak positions) and below 10% for peak area. Furthermore, saliva secreted from the parotid gland proved to have a higher amylase content compared to either secretions from the submandibular/sublingual complex, or whole saliva, as well as amylase enhancement under stimulation. The results suggest that the iCIEF technique can be used to accurately resolve and quantitate amylase isozymes in a rapid and automated fashion, and that gel-filtration should be applied to saliva samples beforehand to allow for optimal purification and characterization.
Collapse
Affiliation(s)
- Atefeh S Zarabadi
- School of Public Health and Health Systems, University of Waterloo, Waterloo, ON, Canada
| | - Tiemin Huang
- Advanced Electrophoresis Solutions Ltd., Cambridge, ON, Canada
| | - John G Mielke
- School of Public Health and Health Systems, University of Waterloo, Waterloo, ON, Canada.
| |
Collapse
|
4
|
Metrology for metalloproteins—where are we now, where are we heading? Anal Bioanal Chem 2013; 405:5697-723. [DOI: 10.1007/s00216-013-6933-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Revised: 03/18/2013] [Accepted: 03/19/2013] [Indexed: 01/10/2023]
|
5
|
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
| |
Collapse
|
6
|
Sampling strategies for capillary isoelectric focusing with electroosmotic zone mobilization assessed by high-resolution dynamic computer simulation. Electrophoresis 2012; 33:970-80. [DOI: 10.1002/elps.201100525] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
7
|
|
8
|
Ou J, Glawdel T, Ren CL, Pawliszyn J. Fabrication of a hybrid PDMS/SU-8/quartz microfluidic chip for enhancing UV absorption whole-channel imaging detection sensitivity and application for isoelectric focusing of proteins. LAB ON A CHIP 2009; 9:1926-1932. [PMID: 19532968 DOI: 10.1039/b821438g] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
A poly(dimethylsiloxane)(PDMS)/SU-8/quartz hybrid chip was developed and applied in the isoelectric focusing (IEF) of proteins with ultraviolet (UV) absorbance-based whole-channel imaging detection (UV-WCID). Each hybrid chip was made of three layers: a PDMS flat top substrate, a bottom quartz substrate and a middle layer of SU-8 photoresist. The SU-8 serves two purposes: it contains the microchannel used for IEF separation, and acts as an optical slit that absorbs UV light below 300 nm improving detection sensitivity in WCID. The novel hybrid design demonstrates a two to three times improvement in sensitivity over a comparable PDMS/PDMS design. In addition, the hybrid chip exhibits increased heat dissipation due to the superior thermal conductivity of the bottom quartz substrate allowing for larger electric fields to be used in separations. The hybrid design with IEF-UV-WCID was successful in resolving a complicated sample, hemoglobin control, with high fidelity.
Collapse
Affiliation(s)
- Junjie Ou
- Department of Chemistry, University of Waterloo, Waterloo, Ontario, CanadaN2L 3G1
| | | | | | | |
Collapse
|
9
|
Development of a simple ampholyte-free isoelectric focusing slab electrophoresis for protein fractionation. J Chromatogr A 2009; 1216:2928-33. [DOI: 10.1016/j.chroma.2008.07.093] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2008] [Revised: 07/24/2008] [Accepted: 07/25/2008] [Indexed: 11/19/2022]
|
10
|
Ou J, Glawdel T, Samy R, Wang S, Liu Z, Ren CL, Pawliszyn J. Integration of Dialysis Membranes into a Poly(dimethylsiloxane) Microfluidic Chip for Isoelectric Focusing of Proteins Using Whole-Channel Imaging Detection. Anal Chem 2008; 80:7401-7. [DOI: 10.1021/ac8010928] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Junjie Ou
- Department of Mechanical and Mechatronics Engineering and Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1, and School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China
| | - Tomasz Glawdel
- Department of Mechanical and Mechatronics Engineering and Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1, and School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China
| | - Razim Samy
- Department of Mechanical and Mechatronics Engineering and Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1, and School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China
| | - Shuwen Wang
- Department of Mechanical and Mechatronics Engineering and Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1, and School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China
| | - Zhen Liu
- Department of Mechanical and Mechatronics Engineering and Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1, and School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China
| | - Carolyn L. Ren
- Department of Mechanical and Mechatronics Engineering and Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1, and School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China
| | - Janusz Pawliszyn
- Department of Mechanical and Mechatronics Engineering and Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1, and School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China
| |
Collapse
|
11
|
Thormann W, Mosher RA. High-resolution computer simulation of electrophoretic mobilization in isoelectric focusing. Electrophoresis 2008; 29:1676-86. [DOI: 10.1002/elps.200700807] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
12
|
Thormann W, Caslavska J, Mosher RA. Modeling of electroosmotic and electrophoretic mobilization in capillary and microchip isoelectric focusing. J Chromatogr A 2007; 1155:154-63. [PMID: 17307189 DOI: 10.1016/j.chroma.2007.01.121] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2006] [Revised: 01/20/2007] [Accepted: 01/25/2007] [Indexed: 11/26/2022]
Abstract
Our dynamic capillary electrophoresis model which uses material specific input data for estimation of electroosmosis was applied to investigate fundamental aspects of isoelectric focusing (IEF) in capillaries or microchannels made from bare fused-silica (FS), FS coated with a sulfonated polymer, polymethylmethacrylate (PMMA) and poly(dimethylsiloxane) (PDMS). Input data were generated via determination of the electroosmotic flow (EOF) using buffers with varying pH and ionic strength. Two models are distinguished, one that neglects changes of ionic strength and one that includes the dependence between electroosmotic mobility and ionic strength. For each configuration, the models provide insight into the magnitude and dynamics of electroosmosis. The contribution of each electrophoretic zone to the net EOF is thereby visualized and the amount of EOF required for the detection of the zone structures at a particular location along the capillary, including at its end for MS detection, is predicted. For bare FS, PDMS and PMMA, simulations reveal that EOF is decreasing with time and that the entire IEF process is characterized by the asymptotic formation of a stationary steady-state zone configuration in which electrophoretic transport and electroosmotic zone displacement are opposite and of equal magnitude. The location of immobilization of the boundary between anolyte and most acidic carrier ampholyte is dependent on EOF, i.e. capillary material and anolyte. Overall time intervals for reaching this state in microchannels produced by PDMS and PMMA are predicted to be similar and about twice as long compared to uncoated FS. Additional mobilization for the detection of the entire pH gradient at the capillary end is required. Using concomitant electrophoretic mobilization with an acid as coanion in the catholyte is shown to provide sufficient additional cathodic transport for that purpose. FS capillaries dynamically double coated with polybrene and poly(vinylsulfonate) are predicted to provide sufficient electroosmotic pumping for detection of the entire IEF gradient at the cathodic column end.
Collapse
Affiliation(s)
- W Thormann
- Department of Clinical Pharmacology, University of Bern, Bern, Switzerland.
| | | | | |
Collapse
|
13
|
Das C, Fan ZH. Effects of separation length and voltage on isoelectric focusing in a plastic microfluidic device. Electrophoresis 2006; 27:3619-26. [PMID: 16915565 DOI: 10.1002/elps.200600013] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
This paper describes the investigation on the effects of separation length and voltage on IEF in a plastic microfluidic device. A LIF, whole-channel imaging detection (WCID) system was developed to monitor proteins while they were moving under an electric field. IEF was carried out in a separation medium consisting of carrier ampholytes and a mixture of linear polymers (hydroxyethylcellulose and hydroxypropylcellulose). We found that the IEF separation resolution is essentially independent of separation length when the same voltage is applied, which agrees with the theory. This result supports the notion that IEF in a microfabricated device leads to more rapid analysis without sacrificing the resolving power. A higher separation voltage also brought about more rapid analysis and superior separation resolution. IEF of two proteins (green fluorescence protein and R-phycoerythrin) was achieved in 1.5 min when 500 V was applied across a 1.9-cm channel. We found that a linear relationship exists between the focusing time and the inverse of the electrical field strength. In addition, we confirmed the phenomenon in which the pH gradient was compressed to the middle of a channel, and we found that the relative amount of the gradient compression decreased with the channel length.
Collapse
Affiliation(s)
- Champak Das
- Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, FL 32611, USA
| | | |
Collapse
|
14
|
Wang J, Zhou S, Huang W, Liu Y, Cheng C, Lu X, Cheng J. CE-based analysis of hemoglobin and its applications in clinical analysis. Electrophoresis 2006; 27:3108-24. [PMID: 16838286 DOI: 10.1002/elps.200500833] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
This review focuses on the developments and trends in CE including CIEF, CZE, MEKC, two-dimensional conjunction of CIEF-capillary gel electrophoresis, and MEKC-CZE on microfluidic devices coupled to different detection approaches, such as UV absorbance, LIF, MS, and chemiluminescence etc. for performing analysis of hemoglobin (Hb), also with an emphasis on its applications in clinical analysis. Analysis of human Hb is of important clinical sense for numerous hemoglobinopathies associated with the congenital defects and abnormal contents of Hb. The diversiform modes render CE a comprehensive primary clinical tool for Hb analysis, which is rapid, sensitive, high-resolution, and not labor-intensive.
Collapse
Affiliation(s)
- Junhua Wang
- Department of Chemistry, Wuhan University, Wuhan 430072, P. R. China
| | | | | | | | | | | | | |
Collapse
|
15
|
Thormann W, Mosher RA. High-resolution computer simulation of the dynamics of isoelectric focusing using carrier ampholytes: Focusing with concurrent electrophoretic mobilization is an isotachophoretic process. Electrophoresis 2006; 27:968-83. [PMID: 16523465 DOI: 10.1002/elps.200500575] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Focusing of four hemoglobins with concurrent electrophoretic mobilization was studied by computer simulation. A dynamic electrophoresis simulator was first used to provide a detailed description of focusing in a 100-carrier component, pH 6-8 gradient using phosphoric acid as anolyte and NaOH as catholyte. These results are compared to an identical simulation except that the catholyte contained both NaOH and NaCl. A stationary, steady-state distribution of carrier components and hemoglobins is produced in the first configuration. In the second, the chloride ion migrates into and through the separation space. It is shown that even under these conditions of chloride ion flux a pH gradient forms. All amphoteric species acquire a slight positive charge upon focusing and the whole pattern is mobilized towards the cathode. The cathodic gradient end is stable whereas the anodic end is gradually degrading due to the continuous accumulation of chloride. The data illustrate that the mobilization is a cationic isotachophoretic process with the sodium ion being the leading cation. The peak height of the hemoglobin zones decreases somewhat upon mobilization, but the zones retain a relatively sharp profile, thus facilitating detection. The electropherograms that would be produced by whole column imaging and by a single detector placed at different locations along the focusing column are presented and show that focusing can be commenced with NaCl present in the catholyte at the beginning of the experiment. However, this may require detector placement on the cathodic side of the catholyte/sample mixture interface.
Collapse
Affiliation(s)
- Wolfgang Thormann
- Department of Clinical Pharmacology, University of Bern, Bern, Switzerland.
| | | |
Collapse
|
16
|
Abstract
The typically low aqueous solubilities of small, hydrophobic organic ampholytic molecules limit the production rates that can be achieved in their isoelectric trapping (IET) separations and call for the use of hydro-organic mixtures as solvents. The compatibility of methanol-water mixtures and poly(ethylene terephthalate) substrate-supported isoelectric polyacrylamide hydrogels, developed for binary IET separations in a Gradiflow BF200IET unit, was investigated. The isoelectric polyacrylamide-based hydrogels retained their functional and mechanical integrities when the methanol concentration in the hydro-organic solvent mixture was kept at or below 25% (v/v). The utility of the hydro-organic media was demonstrated in the purification of a hydrophobic ampholytic compound, technical grade 4-hydroxy-3-(morpholinomethyl) benzoic acid. Production rates as high as 7 mg/h were achieved using small, 15 cm2 active surface area isoelectric membranes.
Collapse
Affiliation(s)
- Evan Shave
- Chemistry Department, Texas A&M University, MS 3255, College Station, TX 77842-3012, USA
| | | |
Collapse
|
17
|
Petersen JR, Okorodudu AO, Mohammad A, Payne DA. Capillary electrophoresis and its application in the clinical laboratory. Clin Chim Acta 2003; 330:1-30. [PMID: 12636924 DOI: 10.1016/s0009-8981(03)00006-8] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Over the past 10 years, capillary electrophoresis (CE) is an analytical tool that has shown great promise in replacing many conventional clinical laboratory methods, especially electrophoresis and high performance liquid chromatography (HPLC). The main attraction of CE was that it was fast, used small amounts of sample and reagents, and was extremely versatile, being able to separate large and small analytes, both neutral and charged. Because of this versatility, numerous methods for clinically relevant analytes have been developed. However, with the exception of the molecular diagnostic and forensic laboratories CE has not had a major impact. A possible reason is that CE is still perceived as requiring above-average technical expertise, precluding its use in a laboratory workforce that is less technically adept. With the introduction of multicapillary instruments that are more automated, less technique-dependent, in addition to the availability of commercial and cost effective test kit methods, CE may yet be accepted as a instrument routinely used in the clinical laboratories. Thus, this review will focus on the areas where CE shows the most potential to have the greatest impact on the clinical laboratory. These include analysis of proteins found in serum, urine, CSF and body fluids, immunosubstraction electrophoresis, hemoglobin variants, lipoproteins, carbohydrate-deficient transferrin (CDT), forensic and therapeutic drug screening, and molecular diagnostics.
Collapse
Affiliation(s)
- John R Petersen
- Department of Pathology, University of Texas Medical Branch, Galveston, USA.
| | | | | | | |
Collapse
|
18
|
Spanik I, Lim P, Vigh G. Use of full-column imaging capillary isoelectric focusing for the rapid determination of the operating conditions in the preparative-scale continuous free-flow isoelectric focusing separation of enantiomers. J Chromatogr A 2002; 960:241-6. [PMID: 12150562 DOI: 10.1016/s0021-9673(02)00504-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A rapid, simple method is proposed here for the identification of the experimental conditions that lead to satisfactory preparative-scale isoelectric focusing enantiomer separations in continuous free-flow electrophoretic units. The method first calls for the use of a commercially available, full-column imaging capillary electrophoretic system to find the background electrolyte composition that generates the largest pI difference between the bands of the enantiomers. The method then calls for the finding of the minimum residence time that permits full development of the pH gradient across the separation chamber of the continuous free-flow electrophoretic unit by measuring the pH in the sample-free carrier electrolyte fractions collected during these runs. Finally, the quality of the predicted preparative-scale separation is verified by analyzing the enantiomer-containing collected fractions by capillary electrophoresis using a 14-sulfated, single-isomer cyclodextrin as resolving agent. The pI difference values and production rate values observed in this work agree well with the literature values that were obtained by much more time-consuming methods.
Collapse
Affiliation(s)
- Ivan Spanik
- Chemistry Department, Texas A&M University, College Station 77842-3012, USA
| | | | | |
Collapse
|
19
|
Hempe JM, Craver RD. Separation of hemoglobin variants with similar charge by capillary isoelectric focusing: value of isoelectric point for identification of common and uncommon hemoglobin variants. Electrophoresis 2000; 21:743-8. [PMID: 10733215 DOI: 10.1002/(sici)1522-2683(20000301)21:4<743::aid-elps743>3.0.co;2-1] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Clinical assays for the primary evaluation of congenital hemoglobin (Hb) disorders must detect and identify a variety of Hb variants. We analyzed hemolysates containing Hb variants with similar charge to evaluate the diagnostic sensitivity and specificity of automated capillary isoelectric focusing (CIEF). Peak separation was observed for each variant in samples containing Hb S, D, and G. The calculated isoelectric points (pI) of these variants were significantly different such that each could be identified in a single run with pI as the sole criterion of identification. The pI of Hb C was significantly different from that of Hb E, C-Harlem, and O-Arab. Hb E, C-Harlem, and O-Arab had similar pI and were not readily differentiated. Hb Koln, M-Saskatoon, Aida, and S/Aida hybrid were readily separated from common Hb variants and detected by CIEF. We conclude that CIEF exhibits both diagnostic sensitivity and specificity, and that pI is an objective and specific criterion of Hb variant identification.
Collapse
Affiliation(s)
- J M Hempe
- Department of Pediatrics, Louisiana State University School of Medicine, New Orleans 70112, USA.
| | | |
Collapse
|
20
|
Tragas C, Pawliszyn J. On-line coupling of high performance gel filtration chromatography with imaged capillary isoelectric focusing using a membrane interface. Electrophoresis 2000; 21:227-37. [PMID: 10634491 DOI: 10.1002/(sici)1522-2683(20000101)21:1<227::aid-elps227>3.0.co;2-m] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
A high performance liquid chromatography system, a sample preparation device, and an imaged capillary IEF (CIEF) instrument are integrated and multiplexed on-line. The system is equivalent to two-dimensional polyacrylamide gel electrophoresis (2-D PAGE), by transferring the principle of 2-D separation to the capillary format. High performance liquid chromatography (HPLC) provides protein separation based on size using a gel filtration chromatography (GFC) column. Each eluted protein is sampled and directed to a novel microdialysis hollow fiber membrane device, where simultaneous desalting and carrier ampholyte mixing occurs. The sample is then driven to the separation column in an on-line fashion, where CIEF takes place. The fluidic technology used by our 2-D system leads to natural automation. The coupling of the two techniques is simple. This is attributed to high speed and efficiency of the sample preparation device that acts as an interface between the two systems, as well as the speed and simplicity of our whole column absorption imaged CIEF instrument. To demonstrate the feasibility of this approach, the separation of a mixture of two model proteins is studied. Sample preparation and CIEF were complete in just 4-5 min, for each of the eluted proteins. Total analysis time is about 24 min. Three-dimensional data representations are constructed. Challenges and methods to further improve our instrument are discussed, and the design of an improved horseshoe-shaped sample preparation sample loop membrane interface is presented and characterized.
Collapse
Affiliation(s)
- C Tragas
- Department of Chemistry, University of Waterloo, ON, Canada
| | | |
Collapse
|
21
|
Mao Q, Pawliszyn J. Capillary isoelectric focusing with whole column imaging detection for analysis of proteins and peptides. JOURNAL OF BIOCHEMICAL AND BIOPHYSICAL METHODS 1999; 39:93-110. [PMID: 10344503 DOI: 10.1016/s0165-022x(99)00006-8] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Whole column imaging detection has been developed for capillary isoelectric focusing (CIEF) of proteins and peptides. In this imaged C1EF technique, a solution of sample and ampholytes was introduced into a short (4-5 cm), internally coated capillary stabilized by a cartridge. After applying high DC voltage, the isoelectric focusing process takes place and the focused zones are monitored in a real-time mode using the imaging detectors developed. Three types of imaging detectors have been developed including refractive index gradient, laser-induced fluorescence (LIF), and absorption. Of these, absorption imaging detection is the most practical at the present time due to its quantitative ability and universal characteristics. Whole column imaging detection eliminates the mobilization step required for single point detection after the focusing process. Therefore, it provides a fast analysis speed (3-5 min for each sample), and avoids the disadvantages associated with the mobilization process, such as distortion of pH gradient and loss in resolution. In this paper, we review the methodology of imaged CIEF as well as progress in instrumental development, IEF performed on a microchip, and the application to protein and peptide analysis.
Collapse
Affiliation(s)
- Q Mao
- Department of Chemistry, University of Waterloo, Ontario, Canada
| | | |
Collapse
|
22
|
Mario N, Baudin B, Bruneel A, Janssens J, Vaubourdolle M. Capillary Zone Electrophoresis for the Diagnosis of Congenital Hemoglobinopathies. Clin Chem 1999. [DOI: 10.1093/clinchem/45.2.285] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Nathalie Mario
- Service de Biochimie A, Hôpital Saint-Antoine, AP-HP, 184 rue du Fbg Saint-Antoine, 75571 Paris Cedex 12, France
| | - Bruno Baudin
- Service de Biochimie A, Hôpital Saint-Antoine, AP-HP, 184 rue du Fbg Saint-Antoine, 75571 Paris Cedex 12, France
- Laboratoire de Biochimie et Glycobiologie, Faculté de Pharmacie Université René Descartes-Paris V, 75006 Paris, France, and
| | - Arnaud Bruneel
- Service de Biochimie A, Hôpital Saint-Antoine, AP-HP, 184 rue du Fbg Saint-Antoine, 75571 Paris Cedex 12, France
| | | | - Michel Vaubourdolle
- Service de Biochimie A, Hôpital Saint-Antoine, AP-HP, 184 rue du Fbg Saint-Antoine, 75571 Paris Cedex 12, France
| |
Collapse
|
23
|
|
24
|
Fang X, Tragas C, Wu J, Mao Q, Pawliszyn J. Recent developments in capillary isoelectric focusing with whole-column imaging detection. Electrophoresis 1998; 19:2290-5. [PMID: 9788311 DOI: 10.1002/elps.1150191307] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Capillary isoelectric focusing (CIEF) is a high resolution technique for protein separation. The on-column single point detector requires a mobilization step which lengthens the analysis time and causes an uneven resolution along the separation column. The real time and whole column imaging detection has been developed for performing CIEF without mobilization. Three types of imaging detection systems have been developed: optical absorption, refractive index gradient, and laser induced fluorescence. This technique provides a fast analysis speed (about 6 min) and a good resolution of 0.03 pH unit level. Using the absorption imaging detector, ampholyte-free IEF in tapered capillary is being demonstrated, which eliminates the interference of the expensive carrier ampholytes for protein detection in UV region. Recent advancements in this imaged CIEF technique as well as its applications are reviewed.
Collapse
Affiliation(s)
- X Fang
- Department of Chemistry, University of Waterloo, ON, Canada
| | | | | | | | | |
Collapse
|
25
|
Abstract
Capillary isoelectric focusing (CIEF) provides excellent resolution of proteins with the advantage that separations are carried out in a capillary format with on-tube detection and automated analysis. Recent advances in the technique provide improved resolution, reproducibility and reliability. This review summarizes improvements in sample preparation, capillary selection, and focusing and zone mobilization procedures which have helped CIEF become a more robust analytical method. New applications are reviewed, in particular the use of CIEF in analysis of biopharmaceutical products.
Collapse
|
26
|
Jenkins MA, Guerin MD. Capillary electrophoresis procedures for serum protein analysis: comparison with established techniques. JOURNAL OF CHROMATOGRAPHY. B, BIOMEDICAL SCIENCES AND APPLICATIONS 1997; 699:257-68. [PMID: 9392378 DOI: 10.1016/s0378-4347(97)00180-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Methods using automated capillary electrophoresis (CE) instrumentation are available for serum protein electrophoresis with monoclonal band quantitation, isoelectric focusing and sodium dodecyl sulphate-polyacrylamide gel electrophoresis separations. The advantages of CE over previous gel methods relate to the time and labour saved by the automated instrumentation. High pI monoclonal bands and cryoglobulin specimens can be successfully analysed by CE. However, if the CE application uses a standard company supplied kit, then the cost savings are often negated by the high cost of the kit. Improvements such as the inclusion of both a UV-Vis as well as a fluorescence detector as standard within the one commercial instrument, the production of coated IEF capillaries with a useful life of at least 100 samples, and the introduction of a capillary array into all commercial instrumentation would ensure greater use of CE within both the clinical and other protein laboratories.
Collapse
Affiliation(s)
- M A Jenkins
- Division of Laboratory Medicine, Austin and Repatriation Medical Center, Heidelberg, Vic., Australia
| | | |
Collapse
|
27
|
Righetti PG, Gelfi C, Conti M. Current trends in capillary isoelectric focusing of proteins. JOURNAL OF CHROMATOGRAPHY. B, BIOMEDICAL SCIENCES AND APPLICATIONS 1997; 699:91-104. [PMID: 9392370 DOI: 10.1016/s0378-4347(96)00208-3] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Isoelectric focusing (IEF) in thin capillaries is reviewed here. After an introduction on the genesis and chemistry of the carrier ampholyte buffers, different approaches to IEF are discussed and evaluated. The classical approach consists on IEF under conditions of suppressed electroosmotic (EOF) flow, usually obtained by covalently bonding hydrophilic polymers to the inner capillary wall. The other approach consists of IEF in dynamically (and partially) coated capillaries, so as to allow a reduced EOF flow to coexist with the IEF process, so that focusing and transport of the train of stacked bands occurs simultaneously. The various experimental parameters: focusing, elution and detection steps, pI measurements, as well as typical drawbacks, such as isoelectric precipitation are evaluated. The review ends with some examples of analytical separations, at the moment mostly limited to focusing of native hemoglobins (normal and point mutants). These separations are compared with those obtained by slab-gel IEF and in immobilized pH gradients.
Collapse
Affiliation(s)
- P G Righetti
- Department of Agricultural and Industrial Biotechnologies, University of Verona, Italy
| | | | | |
Collapse
|
28
|
Frantzen F. Chromatographic and electrophoretic methods for modified hemoglobins. JOURNAL OF CHROMATOGRAPHY. B, BIOMEDICAL SCIENCES AND APPLICATIONS 1997; 699:269-86. [PMID: 9392379 DOI: 10.1016/s0378-4347(97)00245-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The discovery of the clinically important glycohemoglobin adducts and their relation to diabetes mellitus have greatly stimulated the study of other minor post-translational modifications of hemoglobin. Chromatographic and electrophoretic procedures have played an important role in these studies. Today several hemoglobin adducts are known and the formation of adducts with glucose, phosphorylated carbohydrates, urea/cyanate, aspirin, vitamins, acetaldehyde, penicillin and acetyl CoA have been described. Furthermore, new adducts, such as those observed using hemoglobin as a biochemical marker monitoring environmental, occupational and lifestyle exposures to reactive toxic chemicals are constantly being reported. This review deals with chromatographic and electrophoretic separation methods available for the study of non-enzymatic post-translational modifications of hemoglobin. Suitability, perspectives and biomedical applications are discussed.
Collapse
|
29
|
Use of microdialysis for the on-line coupling of capillary isoelectric focusing with electrospray mass spectrometry. J Chromatogr A 1997. [DOI: 10.1016/s0021-9673(97)00430-5] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
|
30
|
Lillard SJ, Yeung ES. Analysis of single erythrocytes by injection-based capillary isoelectric focusing with laser-induced native fluorescence detection. JOURNAL OF CHROMATOGRAPHY. B, BIOMEDICAL APPLICATIONS 1996; 687:363-9. [PMID: 9017459 DOI: 10.1016/s0378-4347(96)00253-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
A modified version of capillary isoelectric focusing (cIEF) was developed to separate hemoglobin variants contained within single human erythrocytes. Laser-induced native fluorescence with 275 nm excitation was used to detect the separated hemoglobins. In this method, baseline fluctuations were minimized and detection sensitivity was improved by using dilute solutions of anolyte, catholyte, and carrier ampholytes (with methylcellulose). Since electroosmotic flow was used for mobilization of the focused bands, separation and detection were integrated into a single step. The capillary was first filled with only ampholyte solution, and the cell (or standard) was injected as in capillary zone electrophoresis. The approximately 90 fl injection volume for individual cells is 7 x 10(4) times lower than those previously reported. Adult (normal and elevated A1), sickle (heterozygous), and fetal erythrocytes were analyzed with the amounts of hemoglobins AO, A1c, S and F determined. The pH gradient for cIEF was linear (r = 0.9984), which allowed tentative identification of Hb Fac. Variants differing by as little as 0.025 pl units were resolved.
Collapse
Affiliation(s)
- S J Lillard
- Department of Chemistry, Iowa State University, Ames 50011, USA
| | | |
Collapse
|
31
|
Affiliation(s)
- T J Pritchett
- Beckman Instruments, Inc., Fullerton, CA 92634-3100, USA.
| |
Collapse
|