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He JY, Xu HX, Li Q, Zheng QY, Wang CZ, Zhou LD, Luo L, Zhang QH, Yuan CS. Specific capture and determination of glycoprotein using a hybrid epitopes and monomers-mediated molecular-imprinted polymer enzyme-free electrochemical biosensor. Mikrochim Acta 2023; 190:118. [PMID: 36884097 DOI: 10.1007/s00604-023-05651-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Accepted: 01/05/2023] [Indexed: 03/09/2023]
Abstract
A novel molecular-imprinted polymer (MIP)-based enzyme-free biosensor was created for the selective detection of glycoprotein transferrin (Trf). For this purpose, MIP-based biosensor for Trf was prepared by electrochemical co-polymerization of novel hybrid monomers 3-aminophenylboronic acid (M-APBA) and pyrrole on a glassy carbon electrode (GCE) modified with carboxylated multi-walled carbon nanotubes (cMWCNTs). Hybrid epitopes of Trf (C-terminal fragment and glycan) have been selected as templates. The produced sensor exhibited great selective recognition ability toward Trf under optimal preparation conditions, offering good analytical range (0.125-1.25 μM) with a detection limit of 0.024 μM. The proposed hybrid epitope in combination with hybrid monomer-mediated imprinting strategy was successfully applied to detect Trf in spiked human serum samples, with recoveries and relative standard deviations ranging from 94.7 to 106.0% and 2.64 to 5.32%, respectively. This study provided a reliable protocol for preparing hybrid epitopes and monomers-mediated MIP for the synergistic and effective determination of glycoprotein in complicated biological samples.
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Affiliation(s)
- Jia-Yuan He
- School of Chemistry and Chemical Engineering, Chongqing University, Chongqing, 400044, China
| | - Hui-Xian Xu
- School of Chemistry and Chemical Engineering, Chongqing University, Chongqing, 400044, China
| | - Qin Li
- School of Chemistry and Chemical Engineering, Chongqing University, Chongqing, 400044, China
| | - Qin-Yue Zheng
- Chongqing Institute for Food and Drug Control, Chongqing, 401121, China
| | - Chong-Zhi Wang
- Tang Center for Herbal Medicine Research and Department of Anesthesia & Critical Care, University of Chicago, Chicago, IL, 60637, USA
| | - Lian-Di Zhou
- Basic Medical College, Chongqing Medical University, Chongqing, 400016, China.
| | - Ling Luo
- Chongqing Cancer Institute, Chongqing University Cancer Hospital, Chongqing, 400030, China.
| | - Qi-Hui Zhang
- School of Chemistry and Chemical Engineering, Chongqing University, Chongqing, 400044, China. .,Tang Center for Herbal Medicine Research and Department of Anesthesia & Critical Care, University of Chicago, Chicago, IL, 60637, USA.
| | - Chun-Su Yuan
- Tang Center for Herbal Medicine Research and Department of Anesthesia & Critical Care, University of Chicago, Chicago, IL, 60637, USA
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Synergistic recognition of transferrin by using performance dual epitope imprinted polymers. Anal Chim Acta 2021; 1186:339117. [PMID: 34756250 DOI: 10.1016/j.aca.2021.339117] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 09/18/2021] [Accepted: 09/21/2021] [Indexed: 11/24/2022]
Abstract
Transferrin (Trf) is a new type of active drug targeting carrier and disease biomarker that regulates the balance of iron ions in human body. The recognition and isolation of Trf is of great significance for disease diagnosis and treatment. Thus, a new type of magnetic dual affinity epitope molecularly imprinted polymer coated on Fe3O4 nanoparticles (Fe3O4@DEMIP) was successfully prepared for specific recognition of Trf. C-terminal nonapeptide and Trf glycan were selected as bi-epitope templates for metal chelation and boron affinity immobilization, respectively. 4-vinylphenylboric acid (4-VP), N-isopropyl acrylamide (NIPAM) and zinc acrylic were used as functional monomers. Results showed that Fe3O4@DEMIP exhibited excellent specific recognition ability adsorption capacity toward Trf, with an adsorption of 43.96 mg g-1 (RSD = 3.28%) and a more satisfactory imprinting factor (about 6.60) than that of other reported imprinting methods. In addition, Fe3O4@DEMIP displayed pH, temperature and magnetic sensitivity properties to realize temperature and pH-controlled recognition and release of target proteins and magnetic rapid separation. Furthermore, the Fe3O4@DEMIP coupled with high-performance liquid chromatography (HPLC) analysis was successfully used for specific recognition of Trf in biosamples. This study provides a reliable protocol for preparing metal chelation and boron affinity dual affinity bi-epitope molecularly imprinted polymers for synergistic and efficient recognition of biomacromolecules in the complex biological systems.
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Caslavska J, Schild C, Thormann W. High-resolution capillary zone electrophoresis and mass spectrometry for distinction of undersialylated and hypoglycosylated transferrin glycoforms in body fluids. J Sep Sci 2019; 43:241-257. [PMID: 31605446 DOI: 10.1002/jssc.201900857] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 10/01/2019] [Accepted: 10/09/2019] [Indexed: 12/21/2022]
Abstract
High-resolution capillary zone electrophoresis is used to distinguish transferrin glycoforms present in human serum, cerebrospinal fluid, and serum treated with neuraminidase and N-glycosidase F. The obtained data are compared to mass spectrometry data from the literature. The main focus is on the analysis of the various asialo-transferrin, monosialo-transferrin, and disialo-transferrin molecules found in these samples. The features of capillary zone electrophoresis and mass spectrometry are reviewed and highlighted in the context of the analysis of undersialylated and hypoglycosylated transferrin molecules. High-resolution capillary zone electrophoresis represents an effective tool to assess the diversity of transferrin patterns whereas mass spectrometry is the method of choice to elucidate structural identification about the glycoforms. Hypoglycosylated transferrin glycoforms present in sera of alcohol abusers and normal subjects are structurally identical to those in sera of patients with a congenital disorder of glycosylation type I. Asialo-transferrin, monosialo-transferrin and disialo-transferrin observed in sera of patients with a type II congenital disorder of glycosylation or a hemolytic uremic syndrome, in cerebrospinal fluid and after treatment of serum with neuraminidase are undersialylated transferrin glycoforms with two N-glycans of varying structure. Undersialylated disialo-transferrin is also observed in sera with high levels of trisialo-transferrin.
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Affiliation(s)
- Jitka Caslavska
- Clinical Pharmacology Laboratory, Institute for Infectious Diseases, University of Bern, Bern, Switzerland
| | - Christof Schild
- Institute of Clinical Chemistry, Inselspital, University Hospital and University of Bern, Bern, Switzerland
| | - Wolfgang Thormann
- Clinical Pharmacology Laboratory, Institute for Infectious Diseases, University of Bern, Bern, Switzerland
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4
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Zhang YD, Huang QW, Ma C, Liu XY, Zhang HX. Magnetic fluorescent molecularly imprinted nanoparticles for detection and separation of transferrin in human serum. Talanta 2018; 188:540-545. [DOI: 10.1016/j.talanta.2018.06.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2018] [Revised: 05/26/2018] [Accepted: 06/01/2018] [Indexed: 11/28/2022]
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5
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Porpiglia NM, De Palo EF, Savchuk SA, Appolonova SA, Bortolotti F, Tagliaro F. A new sample treatment for asialo-Tf determination with capillary electrophoresis: an added value to the analysis of CDT. Clin Chim Acta 2018; 483:256-262. [DOI: 10.1016/j.cca.2018.05.019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Revised: 05/09/2018] [Accepted: 05/09/2018] [Indexed: 11/29/2022]
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6
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Isolation of transferrin by imprinted nanoparticles with magnetic deep eutectic solvents as monomer. Anal Bioanal Chem 2018; 410:6237-6245. [PMID: 29982934 DOI: 10.1007/s00216-018-1232-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2018] [Revised: 05/25/2018] [Accepted: 06/28/2018] [Indexed: 12/21/2022]
Abstract
Transferrin (TrF) is a very important human body glycoprotein and a clinical biomarker which controls the body's iron ion channels and iron ion balance. Any change in TrF concentration and isoform also reflects the emergence of some diseases. In this work, we prepared magnetic molecularly imprinted nanoparticles (deep eutectic solvent-molecular imprinting polymers [DES-MIPs]) with a deep eutectic solvent (DES) as a functional monomer to separate TrF in human serum. The DES dosage for MIP, pH value, and time for adsorption have been optimized, and these materials show special adsorption properties for TrF. The maximum adsorption capacity (Qmax) and dissociation constant KL of the MIP by the Langmuir adsorption curve (R2 = 0.9949) were 37.5 mg/g and 0.015 g/L, respectively. The imprinting factor of the MIP is 3.50 with relative standard deviation (5.63%). In summary, the use of DES as a functional monomer in molecular imprinting technology provides a novel, efficient, and biocompatible method for the isolation and purification of proteins. Graphical abstract ᅟ.
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Tobler M, Caslavska J, Burda P, Thormann W. High-resolution capillary zone electrophoresis for transferrin glycoform analysis associated with congenital disorders of glycosylation. J Sep Sci 2018; 41:2808-2818. [PMID: 29701302 DOI: 10.1002/jssc.201800082] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Revised: 04/18/2018] [Accepted: 04/19/2018] [Indexed: 11/10/2022]
Abstract
High-resolution capillary zone electrophoresis is used to assess the transferrin profile in serum of patients with eight different congenital disorders of glycosylation that represent type I, type II, and mixed type I/II disorders. Capillary zone electrophoresis data are compared to patterns obtained by gel isoelectric focusing. The high-resolution capillary zone electrophoresis method is shown to represent an effective tool to assess the diversity of transferrin patterns. Hypoglycosylated disialo-, monosialo-, and asialo-transferrin in type I cases can be distinguished from the corresponding underdesialylated transferrin glycoforms present in type II disorders. The latter can be separated from and detected ahead of their corresponding hypoglycosylated forms of type I patients. Both types of glycoforms are detected in sera of mixed type I/II patients. The assay has the potential to be used as screening method for congenital disorders of glycosylation. It can be run with a few microliters of serum when microvials are used.
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Affiliation(s)
- Micha Tobler
- Division of Metabolism, University Children's Hospital Zürich, Zürich, Switzerland
| | - Jitka Caslavska
- Clinical Pharmacology Laboratory, Institute for Infectious Diseases, University of Bern, Bern, Switzerland
| | - Patricie Burda
- Division of Metabolism, University Children's Hospital Zürich, Zürich, Switzerland
| | - Wolfgang Thormann
- Clinical Pharmacology Laboratory, Institute for Infectious Diseases, University of Bern, Bern, Switzerland
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8
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Caslavska J, Thormann W. Monitoring of transferrin isoforms in biological samples by capillary electrophoresis. J Sep Sci 2017; 41:303-322. [PMID: 28885776 DOI: 10.1002/jssc.201700914] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Revised: 09/04/2017] [Accepted: 09/04/2017] [Indexed: 11/10/2022]
Abstract
Work dealing with the monitoring of transferrin isoforms in human serum and other body fluids by capillary electrophoresis is reviewed. It comprises capillary zone electrophoresis and capillary isoelectric focusing efforts that led to the exploration and use of assays for the determination of carbohydrate-deficient transferrin as a marker for excessive alcohol intake, genetic variants of transferrin, congenital disorders of glycosylation and β-2-transferrin, which is a marker for cerebrospinal fluid leakage. This paper provides insight into the development, specifications, strengths, weaknesses, and routine use of the currently known capillary electrophoresis based assays suitable to detect transferrin isoforms in body fluids. The achievements reached so far indicate that capillary zone electrophoresis is an attractive technology to monitor the molecular forms of transferrin in biological specimens as the assays do not require an elaborate sample pretreatment and thus can be fully automated for high-throughput analyses on multicapillary instruments. Assays based on capillary isoelectric focusing are less attractive. They require immunoextraction of transferrin from the biological matrix and mobilization after focusing if instrumentation with a whole-column imaging detector is not available. Interactions of the carrier ampholytes with the iron of transferrin may prevent iron saturation and thus provide more complicated isoform patterns.
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Affiliation(s)
- Jitka Caslavska
- Clinical Pharmacology Laboratory, Institute for Infectious Diseases, University of Bern, Bern, Switzerland
| | - Wolfgang Thormann
- Clinical Pharmacology Laboratory, Institute for Infectious Diseases, University of Bern, Bern, Switzerland
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Bortolotti F, Sorio D, Bertaso A, Tagliaro F. Analytical and diagnostic aspects of carbohydrate deficient transferrin (CDT): A critical review over years 2007-2017. J Pharm Biomed Anal 2017; 147:2-12. [PMID: 28912047 DOI: 10.1016/j.jpba.2017.09.006] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2017] [Revised: 08/30/2017] [Accepted: 09/01/2017] [Indexed: 02/07/2023]
Abstract
The need for investigating alcohol abuse by means of objective tools is worldwide accepted. Among the currently available biomarkers of chronic alcohol abuse, carbohydrate-deficient transferrin (CDT) is one of the most used indicator, mainly because of its high specificity. However, some CDT analytical and interpretation aspects are still under discussion, as witnessed by numerous research papers and reviews. The present article presents a critical review of the literature on CDT appeared in the period from 2007 to 2017 (included). The article is organized in the following sections: (1) introduction, (2) pre-analytical aspects (3) analytical aspects (4) diagnostic aspects (5) concluding remarks. As many as 139 papers appeared in the international literature and retrieved by the search engines PubMed, Web of Science and Scopus are quoted.
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Affiliation(s)
- F Bortolotti
- Dept of Diagnostics and Public Health, Unit of Forensic Medicine, University of Verona, Italy.
| | - D Sorio
- Dept of Diagnostics and Public Health, Unit of Forensic Medicine, University of Verona, Italy
| | - A Bertaso
- Dept of Diagnostics and Public Health, Unit of Forensic Medicine, University of Verona, Italy
| | - F Tagliaro
- Dept of Diagnostics and Public Health, Unit of Forensic Medicine, University of Verona, Italy; Institute of Pharmacy and Translational Medicine, Sechenov First Medical University, Moskow, Russia
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Harvey DJ. Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update for 2011-2012. MASS SPECTROMETRY REVIEWS 2017; 36:255-422. [PMID: 26270629 DOI: 10.1002/mas.21471] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Accepted: 01/15/2015] [Indexed: 06/04/2023]
Abstract
This review is the seventh update of the original article published in 1999 on the application of MALDI mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2012. General aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, and fragmentation are covered in the first part of the review and applications to various structural types constitute the remainder. The main groups of compound are oligo- and poly-saccharides, glycoproteins, glycolipids, glycosides, and biopharmaceuticals. Much of this material is presented in tabular form. Also discussed are medical and industrial applications of the technique, studies of enzyme reactions, and applications to chemical synthesis. © 2015 Wiley Periodicals, Inc. Mass Spec Rev 36:255-422, 2017.
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Affiliation(s)
- David J Harvey
- Department of Biochemistry, Oxford Glycobiology Institute, University of Oxford, Oxford, OX1 3QU, UK
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Caslavska J, Lanz C, Burda P, Tobler M, Thormann W. Analysis of genetic variants of transferrin in human serum after desialylation by capillary zone electrophoresis and capillary isoelectric focusing. J Sep Sci 2017; 40:2488-2497. [PMID: 28371325 DOI: 10.1002/jssc.201700211] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Revised: 03/21/2017] [Accepted: 03/21/2017] [Indexed: 12/31/2022]
Abstract
Capillary electrophoresis analysis of transferrin in human serum is used to assess genetic variants after desialylation with neuraminidase and iron saturation to reduce the complexity of the transferrin pattern and thus facilitate the recognition of transferrin polymorphisms. Asialo-transferrin forms are analyzed by capillary zone electrophoresis using assay conditions as for the monitoring of carbohydrate-deficient transferrin or by capillary isoelectric focusing in a pH 5-8 gradient which requires immunoextraction of transferrin prior to analysis. With the carrier ampholytes used, peaks for iron saturated and iron depleted transferrin are monitored which indicates complexation of iron ions by carrier ampholytes. For BC, CD, and BD genetic variants, the expected peaks for B, C, and D forms of transferrin were detected with both methods. Monitoring of CC patterns revealed three cases, namely those producing double peaks in both methods, a double peak in capillary isoelectric focusing only and a double peak in capillary zone electrophoresis only. For all samples analyzed, data obtained by capillary isoelectric focusing could be confirmed with gel isoelectric focusing. The two capillary electrophoresis methods are shown to represent effective tools to assess unusual transferrin patterns, including genetic variants with dissimilar abundances of the two forms.
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Affiliation(s)
- Jitka Caslavska
- Clinical Pharmacology Laboratory, Institute for Infectious Diseases, University of Bern, Bern, Switzerland
| | - Christian Lanz
- Clinical Pharmacology Laboratory, Institute for Infectious Diseases, University of Bern, Bern, Switzerland
| | - Patricie Burda
- Division of Metabolism, University Children's Hospital Zürich, Zürich, Switzerland
| | - Micha Tobler
- Division of Metabolism, University Children's Hospital Zürich, Zürich, Switzerland
| | - Wolfgang Thormann
- Clinical Pharmacology Laboratory, Institute for Infectious Diseases, University of Bern, Bern, Switzerland
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Saçlıgil D, Şenel S, Yavuz H, Denizli A. Purification of transferrin by magnetic immunoaffinity beads. J Sep Sci 2015; 38:2729-36. [PMID: 25980364 DOI: 10.1002/jssc.201500216] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Revised: 04/28/2015] [Accepted: 04/30/2015] [Indexed: 12/26/2022]
Abstract
Immunoaffinity adsorbent for transferrin (Tf) purification was prepared by immobilizing anti-transferrin (Anti-Tf) antibody on magnetic monosizepoly(glycidyl methacrylate) beads, which were synthesized by dispersion polymerization technique in the presence of Fe3 O4 nanopowder and obtained with an average size of 2.0 μm. The magnetic poly(glycidyl methacrylate) (mPGMA) beads were characterized by Fourier transform infrared spectroscopy, swelling tests, scanning electron microscopy, electron spin resonance spectroscopy, thermogravimetric analysis and zeta sizing analysis. The density and swelling ratio of the beads were 1.08 g/cm(3) and 52%, respectively. Anti-Tf molecules were covalently coupled through epoxy groups of mPGMA. Optimum binding of anti-Tf was 2.0 mg/g. Optimum Tf binding from aqueous Tf solutions was determined as 1.65 mg/g at pH 6.0 and initial Tf concentration of 1.0 mg/mL. There was no remarkable loss in the Tf adsorption capacity of immunoaffinity beads after five adsorption-desorption cycles. Tf adsorption from artificial plasma was also investigated and the purity of the Tf molecules was shown with gel electrophoresis studies.
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Affiliation(s)
- Dilara Saçlıgil
- Hacettepe University, Department of Chemistry, Beytepe, Ankara, Turkey
| | - Serap Şenel
- Hacettepe University, Department of Chemistry, Beytepe, Ankara, Turkey
| | - Handan Yavuz
- Hacettepe University, Department of Chemistry, Beytepe, Ankara, Turkey
| | - Adil Denizli
- Hacettepe University, Department of Chemistry, Beytepe, Ankara, Turkey
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First evaluation of a multi-capillary electrophoresis CDT assay on Helena Biosciences' V8 analyser. Clin Biochem 2014; 47:228-32. [DOI: 10.1016/j.clinbiochem.2014.08.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Revised: 08/14/2014] [Accepted: 08/16/2014] [Indexed: 11/21/2022]
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Caslavska J, Joneli J, Wanzenried U, Schiess J, Lanz C, Thormann W. Determination of genetic transferrin variants in human serum by high-resolution capillary zone electrophoresis†. J Sep Sci 2014; 37:1663-70. [DOI: 10.1002/jssc.201400243] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Revised: 04/08/2014] [Accepted: 04/08/2014] [Indexed: 12/17/2022]
Affiliation(s)
- Jitka Caslavska
- Clinical Pharmacology Laboratory; Institute for Infectious Diseases; University of Bern; Bern Switzerland
| | - Jeannine Joneli
- Clinical Pharmacology Laboratory; Institute for Infectious Diseases; University of Bern; Bern Switzerland
| | - Ursula Wanzenried
- Clinical Pharmacology Laboratory; Institute for Infectious Diseases; University of Bern; Bern Switzerland
| | - Jeannette Schiess
- Clinical Pharmacology Laboratory; Institute for Infectious Diseases; University of Bern; Bern Switzerland
| | - Christian Lanz
- Laboratory of Phytopharmacology, Bioanalytics and Pharmacokinetics; Department of Clinical Research; University of Bern; Bern Switzerland
| | - Wolfgang Thormann
- Clinical Pharmacology Laboratory; Institute for Infectious Diseases; University of Bern; Bern Switzerland
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Nowak P, Śpiewak K, Nowak J, Brindell M, Woźniakiewicz M, Stochel G, Kościelniak P. Selective separation of ferric and non-ferric forms of human transferrin by capillary micellar electrokinetic chromatography. J Chromatogr A 2014; 1341:73-8. [PMID: 24690308 DOI: 10.1016/j.chroma.2014.03.037] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Revised: 03/09/2014] [Accepted: 03/11/2014] [Indexed: 11/18/2022]
Abstract
The previously published method allowing the separation of non-ferric (iron-free) and ferric (iron-saturated) forms of human serum transferrin via capillary electrophoresis has been further developed. Using a surface response methodology and a three-factorial Doehlert design we have established a new optimized running buffer composition: 50mM Tris-HCl, pH 8.5, 22.5% (v/v) methanol, 17.5mM SDS. As a result, two previously unobserved monoferric forms of protein have been separated and identified, moreover, the loss of ferric ions from transferrin during electrophoretic separation has been considerably reduced by methanol, and the method selectivity has been yet increased resulting in a total separation of proteins exerting only subtle or none difference in mass-to-charge ratio. The new method has allowed us to monitor the gradual iron saturation of transferrin by mixing the iron-free form of protein with the buffers with different concentrations of ferric ions. It revealed continuously changing contribution of monoferric forms, characterized by different affinities of two existing iron binding sites on N- and C-lobes of protein, respectively. Afterwards, the similar experiment has been conducted on-line, i.e. inside the capillary, comparing the effectiveness of two possible modes of the reactant zones mixing: diffusion mediated and electrophoretically mediated ones. Finally, the total time of separation has been decreased down to 4min, taking the advantage from a short-end injection strategy and maintaining excellent selectivity.
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Affiliation(s)
- Paweł Nowak
- Jagiellonian University in Kraków, Faculty of Chemistry, Department of Analytical Chemistry, Kraków, Poland
| | - Klaudyna Śpiewak
- Jagiellonian University in Kraków, Faculty of Chemistry, Department of Inorganic Chemistry, Kraków, Poland
| | - Julia Nowak
- Jagiellonian University in Kraków, Faculty of Chemistry, Department of Analytical Chemistry, Kraków, Poland
| | - Małgorzata Brindell
- Jagiellonian University in Kraków, Faculty of Chemistry, Department of Inorganic Chemistry, Kraków, Poland
| | - Michał Woźniakiewicz
- Jagiellonian University in Kraków, Faculty of Chemistry, Department of Analytical Chemistry, Kraków, Poland.
| | - Grażyna Stochel
- Jagiellonian University in Kraków, Faculty of Chemistry, Department of Inorganic Chemistry, Kraków, Poland
| | - Paweł Kościelniak
- Jagiellonian University in Kraków, Faculty of Chemistry, Department of Analytical Chemistry, Kraków, Poland
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