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Development of a microcolumn one-site immunometric assay for a protein biomarker: Analysis of alpha 1-acid glycoprotein. J Chromatogr A 2019; 1610:460558. [PMID: 31564560 DOI: 10.1016/j.chroma.2019.460558] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 09/16/2019] [Accepted: 09/19/2019] [Indexed: 12/26/2022]
Abstract
A one-site immunometric assay based on affinity microcolumns was developed for the analysis of alpha1-acid glycoprotein (AGP) as a model protein biomarker. In this assay, a sample containing AGP was incubated with an excess amount of a labeled binding agent, such as fluorescein-labeled anti-AGP antibodies or Fab fragments. The excess binding agent was removed by passing this mixture through a microcolumn that contained an immobilized form of AGP, while the signal was measured for the binding agent-AGP complex in the non-retained fraction. Theoretical and practical factors were both considered in selecting the concentration of labeled binding agent, the incubation time of this agent with the sample, and the application conditions for this mixture onto the microcolumn. The effects of using various labeling methods and intact antibodies vs Fab fragments were also considered. The final assay was performed with fluorescein-labeled anti-AGP antibodies and a 2.1 mm i.d. × 1.0 cm AGP microcolumn operated at 0.30 mL min-1. This method required only 1 µL of serum or plasma, had a detection limit of 0.63 nM AGP, and gave a potential throughput of 2 min per sample. This assay was used to measure AGP in normal serum and plasma from patients with systemic lupus erythematosus, giving good agreement with the literature and a reference method. The same approach and guidelines can be used to create assays for other protein biomarkers by changing the labeled binding agent and immobilized protein within the microcolumn.
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Development of microcolumn-based one-site immunometric assays for protein biomarkers. J Chromatogr A 2014; 1366:92-100. [PMID: 25263063 DOI: 10.1016/j.chroma.2014.09.026] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Revised: 09/03/2014] [Accepted: 09/10/2014] [Indexed: 11/21/2022]
Abstract
One-site immunometric assays that utilize affinity microcolumns were developed and evaluated for the analysis of protein biomarkers. This approach used labeled antibodies that were monitored through on-line fluorescence or near-infrared (NIR) fluorescence detection. Human serum albumin (HSA) was utilized as a model target protein for this approach. In these assays, a fixed amount of labeled anti-HSA antibodies was mixed with samples or standards containing HSA, followed by the injection of this mixture onto an HSA microcolumn to remove excess antibodies and detect the non-retained labeled antibodies that were bound to HSA from the sample. The affinity microcolumns were 2.1mm i.d. ×5mm and contained 8-9nmol of immobilized HSA. These microcolumns were used from 0.10 to 1.0mL/min and gave results within 35s to 2.8min of sample injection. Limits of detection down to 0.10-0.28ng/mL (1.5-4.2pM) or 25-30pg/mL (0.38-0.45pM) were achieved when using fluorescein or a NIR fluorescent dye as the label, with an assay precision of ±0.1-4.2%. Several parameters were examined during the optimization of these assays, and general guidelines and procedures were developed for the extension of this approach for use with other types of affinity microcolumns and protein biomarkers.
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Trojanowicz M, Kaniewska M. Flow methods in chiral analysis. Anal Chim Acta 2013; 801:59-69. [DOI: 10.1016/j.aca.2013.09.025] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2013] [Revised: 08/31/2013] [Accepted: 09/10/2013] [Indexed: 11/30/2022]
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Hubbard MA, Thorkildson P, Welch WH, Kozel TR. Stereo-selective binding of monoclonal antibodies to the poly-γ-D-glutamic acid capsular antigen of Bacillus anthracis. Mol Immunol 2013; 55:337-44. [PMID: 23602451 PMCID: PMC3783358 DOI: 10.1016/j.molimm.2013.03.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2012] [Revised: 03/04/2013] [Accepted: 03/13/2013] [Indexed: 01/06/2023]
Abstract
Bacillus anthracis is surrounded by an anti-phagocytic capsule that is entirely composed of γ-linked D-glutamic acid (γDPGA). γDPGA is required for virulence and is produced in large quantities following spore germination. We have previously described the isolation of several γDPGA-reactive mAbs. The reagents are effective in both immunoprotection and diagnostic applications. The current work was done to further investigate the specificity of γDPGA-reactive mAbs. The specificity of each mAb was characterized using surface plasmon resonance. Our results indicate that each mAb is stereoselective for binding to D-glutamic acid oligomers, but to varying degrees. In particular, mAb F26G3 is highly selective for γDPGA; alterations in stereochemistry disrupted recognition. These differences in mAb reactivity suggest that binding of γDPGA by mAb F26G3 is more specific than non-directional ionic interactions between a negatively charged antigen and a positively charged antibody.
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Affiliation(s)
- Mark A. Hubbard
- Department of Microbiology and Immunology, University of Nevada School of Medicine, Reno, Nevada, 89557 USA
- Cellular and Molecular Biology Graduate Program, University of Nevada School of Medicine, Reno, Nevada, 89557 USA
| | - Peter Thorkildson
- Department of Microbiology and Immunology, University of Nevada School of Medicine, Reno, Nevada, 89557 USA
| | - William H. Welch
- Department of Biochemistry and Molecular Biology, University of Nevada School of Medicine, Reno, Nevada, 89557 USA
| | - Thomas R. Kozel
- Department of Microbiology and Immunology, University of Nevada School of Medicine, Reno, Nevada, 89557 USA
- Cellular and Molecular Biology Graduate Program, University of Nevada School of Medicine, Reno, Nevada, 89557 USA
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Eleniste PP, Hofstetter H, Hofstetter O. Expression and characterization of an enantioselective antigen-binding fragment directed against α-amino acids. Protein Expr Purif 2013; 91:20-9. [PMID: 23827208 PMCID: PMC3816624 DOI: 10.1016/j.pep.2013.06.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Revised: 06/19/2013] [Accepted: 06/24/2013] [Indexed: 11/18/2022]
Abstract
This work describes the design and expression of a stereoselective Fab that possesses binding properties comparable to those displayed by the parent monoclonal antibody. Utilizing mRNA from hybridoma clones that secrete a stereoselective anti-l-amino acid antibody, a corresponding biotechnologically produced Fab was generated. For that, appropriate primers were designed based on extensive literature and databank searches. Using these primers in PCR resulted in successful amplification of the VH, VL, CL and CH1 gene fragments. Overlap PCR was utilized to combine the VH and CH1 sequences and the VL and CL sequences, respectively, to obtain the genes encoding the HC and LC fragments. These sequences were separately cloned into the pEXP5-CT/TOPO expression vector and used for transfection of BL21(DE3) cells. Separate expression of the two chains, followed by assembly in a refolding buffer, yielded an Fab that was demonstrated to bind to l-amino acids but not to recognize the corresponding d-enantiomers.
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Affiliation(s)
| | - Heike Hofstetter
- Department of Chemistry and Biochemistry, Northern Illinois University,
DeKalb, Illinois 60115, USA
| | - Oliver Hofstetter
- Department of Chemistry and Biochemistry, Northern Illinois University,
DeKalb, Illinois 60115, USA
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Immunoaffinity chromatography: an introduction to applications and recent developments. Bioanalysis 2011; 2:769-90. [PMID: 20640220 DOI: 10.4155/bio.10.31] [Citation(s) in RCA: 132] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Immunoaffinity chromatography (IAC) combines the use of LC with the specific binding of antibodies or related agents. The resulting method can be used in assays for a particular target or for purification and concentration of analytes prior to further examination by another technique. This review discusses the history and principles of IAC and the various formats that can be used with this method. An overview is given of the general properties of antibodies and of antibody-production methods. The supports and immobilization methods used with antibodies in IAC and the selection of application and elution conditions for IAC are also discussed. Several applications of IAC are considered, including its use in purification, immunodepletion, direct sample analysis, chromatographic immunoassays and combined analysis methods. Recent developments include the use of IAC with CE or MS, ultrafast immunoextraction methods and the use of immunoaffinity columns in microanalytical systems.
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Gao C, Fan S. Influence of Zone Stacking Sequences on CL Intensity and Determination of Histidine in Sequential Injection Analysis. ANAL LETT 2008. [DOI: 10.1080/00032710802119152] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Zeleke JM, Smith GB, Hofstetter H, Hofstetter O. Enantiomer separation of amino acids in immunoaffinity micro LC-MS. Chirality 2007; 18:544-50. [PMID: 16642491 DOI: 10.1002/chir.20286] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Chiral immunoaffinity microbore columns were directly interfaced with MS detection, and the effect of column length and temperature on the enantiomer separation of a number of underivatized aromatic and aliphatic amino acids was investigated utilizing an antibody chiral stationary phase that had been prepared by immobilizing a monoclonal anti-D-amino acid antibody onto silica. The stronger affinity of the antibody towards aromatic and bulky amino acids allowed separation of such analytes in a 0.75 x 150 mm column, while an increase in column length enabled separation of more weakly bound compounds. The strength of interaction between chiral selector and analytes could be modulated conveniently by lowering the temperature. For the first time, simultaneous enantiomer separation of mixtures of amino acids was achieved on antibody-based chiral stationary phases using extracted ion chromatograms.
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Affiliation(s)
- Jessica M Zeleke
- Department of Chemistry and Biochemistry, Northern Illinois University, DeKalb, Illinois 60115-2862, USA
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Koidl J, Hödl H, Schmid MG, Konrad M, Petschauer S, Kostner GM, Gübitz G. Chiral separation of T3 enantiomers using stereoselective antibodies as a selector in micro-HPLC. JOURNAL OF BIOCHEMICAL AND BIOPHYSICAL METHODS 2006; 69:33-42. [PMID: 16697467 DOI: 10.1016/j.jbbm.2006.03.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2005] [Revised: 03/21/2006] [Accepted: 03/26/2006] [Indexed: 11/19/2022]
Abstract
This work deals with the application of stereoselective antibodies against L-T3 as a tailor-made chiral selector in micro-HPLC. The separations were performed in microbore columns using commercially available anti-L-T3 antibodies chemically bonded to 5 microm silica gel. The enantiomers of T3 were baseline separated under mild continuous isocratic elution conditions using 10 mM phosphate buffer, pH 7.4. The D-enantiomer eluted with the void volume, while the L-enantiomer was retained by the antibody phase and eluted second. An indirect competitive and non-competitive enzyme linked immunosorbent assay (ELISA) was used for testing the stereoselectivity of anti-L-T3 antibodies.
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Affiliation(s)
- Julia Koidl
- Institute of Pharmaceutical Sciences, Department of Pharmaceutical Chemistry, Karl-Franzens-University, Universitätsplatz 1, A-8010 Graz, Austria
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Gübitz G, Schmid MG. Chiral separation principles in chromatographic and electromigration techniques. Mol Biotechnol 2006; 32:159-80. [PMID: 16444017 DOI: 10.1385/mb:32:2:159] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Almost half of the drugs in use today are chiral. It is well established that the pharmacological activity is mostly restricted to one of the enantiomers (eutomer). There can be qualitative and quantitative differences in the activity of the enantiomers. In many cases, the inactive enantiomer (distomer) shows unwanted side effects or even toxic effects. Even if the side effects are not that drastic, the distomer has to be metabolized and this represents an unnecessary burden for the organism. Therefore, the development of methods for the separation of enantiomers, both on analytical and preparative scale, has become increasingly important. Chromatographic techniques such as thin layer chromatography (TLC), gas chromatography (GC), supercritical fluid chromatography (SFC), and above all high-performance liquid chromatography (HPLC) have been used for enantiomer separation for about two decades. More recently, electromigration techniques, such as capillary electrophoresis and capillary electrochromatography, have been shown to be powerful alternatives to chromatographic methods. This review gives a short overview of different chiral separation principles and their application. Several new developments are discussed.
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Affiliation(s)
- Gerald Gübitz
- Institute of Pharmaceutical Sciences, Department of Pharmaceutical Chemistry, Karl-Franzens University, Universitätsplatz 1, A-8010 Graz, Austria
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Wang S, Du L, Lin S, Zhuang H. Flow Injection Chemiluminescence for the Determination of Estriol via a Noncompetitive Enzyme Immunoassay. Mikrochim Acta 2006. [DOI: 10.1007/s00604-006-0568-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Fiamegos YC, Stalikas CD. Gas chromatographic determination of amino acids via one-step phase-transfer catalytic pentafluorobenzylation–preconcentration. J Chromatogr A 2006; 1110:66-72. [PMID: 16487532 DOI: 10.1016/j.chroma.2006.01.074] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2005] [Revised: 01/10/2006] [Accepted: 01/17/2006] [Indexed: 11/28/2022]
Abstract
The gas chromatographic determination of amino acids via their simultaneous extraction, preconcentration and pentafluorobenzylation is reported. Using phase-transfer catalysis (PTC), the amino acids under study were transformed to their pentafluorobenzyl adducts. The method was tested for different catalysts and tetrabutylammonium bromide provided favorable features in comparison to the other PTCs. The derivatization procedure was optimized and the best reaction conditions are given. With the exception of arginine, 19 amino acids were converted to volatile derivatives and analyzed with GC/MS and GC/FID at low concentration levels with acceptable sensitivity and good reproducibility. The LODs were found to range from 0.7 to 2.3microM for the GC/MS analyses and from 1.7 to 6.9microM for GC/FID analyses. The method practicability and applicability were confirmed by the analysis of urine, fruit juice and wheat flour for the determination of the amino acids under study. Protein-bound amino acids were analyzed after an alkaline hydrolysis step with 5M NaOH applying this method to wheat flour with an overall procedure duration less than 12h. The optimized protocol was applied to these samples without any pretreatment and their amino acid concentrations were calculated from the appropriate calibration plots.
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Affiliation(s)
- Yiannis C Fiamegos
- Laboratory of Analytical Chemistry, Chemistry Department, University of Ioannina, University Campus, 45110 Ioannina, Greece.
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Hofstetter H, Hofstetter O. Antibodies as tailor-made chiral selectors for detection and separation of stereoisomers. Trends Analyt Chem 2005. [DOI: 10.1016/j.trac.2005.04.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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