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Liu DM, Chen J, Shi YP. An online immobilized α-glucosidase microreactor for enzyme kinetics and inhibition assays. RSC Adv 2015. [DOI: 10.1039/c5ra07982a] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
A novel online α-glucosidase-immobilized microreactor was developed by immobilizing α-glucosidase on capillary inner wall. The microreactor combination with capillary electrophoresis was applied in studying enzyme kinetics and inhibition kinetics.
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Affiliation(s)
- Dong-Mei Liu
- Key Laboratory of Chemistry of Northwestern Plant Resources
- Key Laboratory for Natural Medicine of Gansu Province
- Lanzhou Institute of Chemical Physics
- Chinese Academy of Sciences
- Lanzhou 730000
| | - Juan Chen
- Key Laboratory of Chemistry of Northwestern Plant Resources
- Key Laboratory for Natural Medicine of Gansu Province
- Lanzhou Institute of Chemical Physics
- Chinese Academy of Sciences
- Lanzhou 730000
| | - Yan-Ping Shi
- Key Laboratory of Chemistry of Northwestern Plant Resources
- Key Laboratory for Natural Medicine of Gansu Province
- Lanzhou Institute of Chemical Physics
- Chinese Academy of Sciences
- Lanzhou 730000
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2
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Inhibition of α-Amylase Activities by Extracts of Chinese Yam. PROCEEDINGS OF THE 2012 INTERNATIONAL CONFERENCE ON APPLIED BIOTECHNOLOGY (ICAB 2012) 2014. [DOI: 10.1007/978-3-642-37925-3_159] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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3
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Immobilized capillary tyrosinase microreactor for inhibitor screening in natural extracts by capillary electrophoresis. J Pharm Biomed Anal 2013; 84:36-40. [DOI: 10.1016/j.jpba.2013.05.023] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Revised: 05/13/2013] [Accepted: 05/17/2013] [Indexed: 11/19/2022]
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Iqbal S, Nisar ur Rehman, Kortz U, Iqbal J. Development of a fast and efficient CE enzyme assay for the characterization and inhibition studies of α-glucosidase inhibitors. J Sep Sci 2013; 36:3623-8. [PMID: 23996827 DOI: 10.1002/jssc.201300758] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2013] [Revised: 08/16/2013] [Accepted: 08/20/2013] [Indexed: 11/10/2022]
Abstract
The inhibition of the α-glucosidase enzyme plays an important role in the treatment of diabetes mellitus. We have established a highly sensitive, fast, and convenient CE method for the characterization of the enzyme and inhibition studies of α-glucosidase inhibitors. The separation conditions were optimized; the pH value and concentration of the borate-based separation buffer were optimized in order to achieve baseline separation of p-nitrophenyl-α-d-glucopyranoside and p-nitrophenolate. The optimized method using 25 mM tetraborate buffer, pH 9.5, was evaluated in terms of repeatability, LOD, LOQ, and linearity. The LOD and LOQ were 0.32 and 1.32 μM for p-nitrophenyl-α-D-glucopyranoside and 0.83 and 3.42 μM for p-nitrophenolate, respectively. The value of the Michaelis-Menten constant (K(m)) determined for the enzyme is 0.61 mM, which is in good agreement with the reported data. The RSDs (n = 6) for the migration time was 0.67 and 1.83% for substrate and product, respectively. In the newly established CE method, the separation of the reaction analytes was completed in <4 min. The developed CE method is rapid and simple for measuring enzyme kinetics and for assaying inhibitors.
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Affiliation(s)
- Shoaib Iqbal
- Department of Pharmaceutical Sciences, COMSATS Institute of Information Technology, Abbottabad, Pakistan
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Iqbal S, Nisar-ur-Rahman, Iqbal J. A capillary electrophoresis-based enzyme assay for kinetics and inhibition studies of carbonic anhydrase. Anal Biochem 2013; 444:16-21. [PMID: 24064297 DOI: 10.1016/j.ab.2013.09.018] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Revised: 09/10/2013] [Accepted: 09/13/2013] [Indexed: 01/19/2023]
Abstract
In the current study, capillary electrophoresis (CE)-based enzyme assay for characterization and inhibition study of bovine carbonic anhydrase II (bCA II) was developed. The developed method is the first CE assay for carbonic anhydrase (CA). The method was optimized in order to get short analysis time, minimal sample volume consumption, and high resolution of substrate and product. The CE conditions were optimized as follows: fused-silica capillary (30 cm effective length×75 μm i.d.), pressure injection for 5s, 20mM sodium borate buffer (pH 9.0), constant voltage of 15 kV, constant capillary temperature of 25 °C, and detection at 260 nm. For precise measurements, uridine was used as an internal standard during optimization of the CE methods. The limits of detection and quantification for p-nitrophenyl acetate (p-NPA) were 3.01 and 9.12 μM, respectively, whereas for p-nitrophenolate they were 2.05 and 6.22 μM, respectively. The performance of the developed method was confirmed by determination of kinetic parameters (i.e., K(m) and V(max) of bCA for p-NPA); the inhibition constant (K(i)) was determined for furosemide, a standard inhibitor of CA. The new method proved to be fast and efficient, and it can be used for the investigation of inhibitors of all isoforms of CAs.
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Affiliation(s)
- Shoaib Iqbal
- Department of Pharmaceutical Sciences, COMSATS Institute of Information Technology, Abbottabad 22060, Pakistan
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Nehmé H, Nehmé R, Lafite P, Routier S, Morin P. In-capillary reactant mixing for monitoring glycerol kinase kinetics by CE. J Sep Sci 2013; 36:2151-7. [DOI: 10.1002/jssc.201300063] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2013] [Revised: 04/02/2013] [Accepted: 04/03/2013] [Indexed: 01/06/2023]
Affiliation(s)
- Hala Nehmé
- Institut de Chimie Organique et Analytique (ICOA); Université d'Orléans; Orléans France
| | - Reine Nehmé
- Institut de Chimie Organique et Analytique (ICOA); Université d'Orléans; Orléans France
| | - Pierre Lafite
- Institut de Chimie Organique et Analytique (ICOA); Université d'Orléans; Orléans France
| | - Sylvain Routier
- Institut de Chimie Organique et Analytique (ICOA); Université d'Orléans; Orléans France
| | - Philippe Morin
- Institut de Chimie Organique et Analytique (ICOA); Université d'Orléans; Orléans France
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Nehme H, Nehme R, Lafite P, Routier S, Morin P. New development in in-capillary electrophoresis techniques for kinetic and inhibition study of enzymes. Anal Chim Acta 2012; 722:127-35. [PMID: 22444544 DOI: 10.1016/j.aca.2012.02.003] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2011] [Revised: 01/30/2012] [Accepted: 02/02/2012] [Indexed: 11/18/2022]
Abstract
Enzymes are often quantified by measuring their biological activity. Capillary electrophoresis is gaining its position in this field due to the ongoing trend to miniaturize biochemical assays. The aim of this work was to compare pre-capillary (off-line) and in-capillary electrophoresis techniques for studying enzymatic activity. The β-galactosidase (β-Gal) was chosen as a model enzyme. Each technique was optimized independently in order to decrease analyte consumption (to few tens of nanoliters), incubation time (to few seconds) and analysis time (below 1 min). Several experimental parameters (ionic strength of the background electrolyte (BGE) and of the incubation buffer, incubation time, injected volumes, …) were optimized by following peak efficiencies, resolution and repeatability. To monitor the performance of each technique, the catalytic constants (V(max) and K(m)) of 4-nitro-phenyl-d-galactopyranoside (PNPG) hydrolysis by β-Gal as well as the inhibition constants (K(i) and IC(50)) by a competitive inhibitor 2-nitrophenyl-1-thio-β-d-thiogalactopyranoside (ONPTG) were determined. The results obtained were cross compared and were also evaluated by comparison to a standard spectrophotometric method. EMMA proved to be the best technique in terms of sample consumption and speed. The short-end injection was successfully used which speeded-up electrophoretic analysis (<0.8 min). It is a very powerful tool for studying enzymatic inhibition. Usually, the inhibitor is injected in the capillary mixed to the substrate especially when both have similar mobilities. We show in this work, for the first time, that combining at-inlet reaction with EMMA-CE allows enzyme inhibition to be realized without any prior mixing of the substrate and the inhibitor. This approach is very interesting for screening inhibitors, rapidly and without excessive substrate consumption.
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Affiliation(s)
- Hala Nehme
- Institut de Chimie Organique et Analytique, Université d'Orléans, CNRS FR 2708, UMR 7311, Orléans, France
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Screening α-glucosidase inhibitors from traditional Chinese drugs by capillary electrophoresis with electrophoretically mediated microanalysis. J Pharm Biomed Anal 2010; 53:1250-3. [DOI: 10.1016/j.jpba.2010.07.041] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2010] [Revised: 07/26/2010] [Accepted: 07/27/2010] [Indexed: 12/12/2022]
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9
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Iqbal J, Burbiel JC, Müller CE. Development of off-line and on-line capillary electrophoresis methods for the screening and characterization of adenosine kinase inhibitors and substrates. Electrophoresis 2006; 27:2505-17. [PMID: 16786483 DOI: 10.1002/elps.200500944] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Fast and convenient CE assays were developed for the screening of adenosine kinase (AK) inhibitors and substrates. In the first method, the enzymatic reaction was performed in a test tube and the samples were subsequently injected into the capillary by pressure and detected by their UV absorbance at 260 nm. An MEKC method using borate buffer (pH 9.5) containing 100 mM SDS (method A) was suitable for separating alternative substrates (nucleosides). For the CE determination of AMP formed as a product of the AK reaction, a phosphate buffer (pH 7.5 or 8.5) was used and a constant current (95 microA) was applied (method B). The methods employing a fused-silica capillary and normal polarity mode provided good resolution of substrates and products of the enzymatic reaction and a short analysis time of less than 10 min. To further optimize and miniaturize the AK assays, the enzymatic reaction was performed directly in the capillary, prior to separation and quantitation of the product employing electrophoretically mediated microanalysis (EMMA, method C). After hydrodynamic injection of a plug of reaction buffer (20 mM Tris-HCl, 0.2 mM MgCl2, pH 7.4), followed by a plug containing the enzyme, and subsequent injection of a plug of reaction buffer containing 1 mM ATP, 100 microM adenosine, and 20 microM UMP as an internal standard (I.S.), as well as various concentrations of an inhibitor, the reaction was initiated by the application of 5 kV separation voltage (negative polarity) for 0.20 min to let the plugs interpenetrate. The voltage was turned off for 5 min (zero-potential amplification) and again turned on at a constant current of -60 microA to elute the products within 7 min. The method employing a polyacrylamide-coated capillary of 20 cm effective length and reverse polarity mode provided good resolution of substrates and products. Dose-response curves and calculated K(i) values for standard antagonists obtained by CE were in excellent agreement with data obtained by the standard radioactive assay.
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Affiliation(s)
- Jamshed Iqbal
- Department of Pharmaceutical Chemistry Poppelsdorf, Pharmaceutical Institute, University of Bonn, Bonn, Germany
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Glatz Z. Determination of enzymatic activity by capillary electrophoresis. J Chromatogr B Analyt Technol Biomed Life Sci 2006; 841:23-37. [PMID: 16574509 DOI: 10.1016/j.jchromb.2006.02.051] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2006] [Revised: 02/20/2006] [Accepted: 02/21/2006] [Indexed: 10/24/2022]
Abstract
Enzymes are biological catalysts that play an important role in biochemical reactions necessary for normal growth, maturation and reproduction through whole live world. Their accurate quantitation in biological samples is important in many fields of biochemistry, not only in routine biochemistry and in fundamental research, but also in clinical and pharmacological research and diagnosis. Since the direct measurement of enzymes by masses is impossible, they must be quantified by their catalytic activities. Many different methods have been applied for this purpose so far. Although photometric methods are undoubtedly the most frequently used, separation methods will further gain their position in this field. The article reviews different possibilities for the assay of enzymatic activity by means of capillary electrophoresis (CE). Both the off-line and on-line enzyme assays based on CE are discussed.
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Affiliation(s)
- Zdenek Glatz
- Department of Biochemistry, Faculty of Science, Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic.
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Sanders BD, Slotcavage RL, Scheerbaum DL, Kochansky CJ, Strein TG. Increasing the efficiency of in-capillary electrophoretically mediated microanalysis reactions via rapid polarity switching. Anal Chem 2005; 77:2332-7. [PMID: 15828765 PMCID: PMC1403743 DOI: 10.1021/ac048595u] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We report herein a new approach to enhance the sensitivity or speed of CE-based methods that involve in-line reactions. Rapid polarity switching (RPS) is used as a novel means for in-line mixing of two reactant solutions via rapid (1-5 s) and sequential switching of the applied potential field. By employing the RPS approach with a model chemical reaction, that between creatinine and alkaline picrate, significant enhancement in sensitivity (or a decrease in analysis time) is realized. Both increased convection and electrophoretic stacking of the ionic reagent appear to contribute to the rise in apparent reaction rate. When coupled with in-line chemistry of the Jaffe method for creatinine, the RPS methodology allows for 3-fold faster determination of creatinine in the concentration range needed for the analysis of clinical blood serum specimens. The new approach also allows the analysis to be performed without the need for the cumbersome and problematic enhanced sensitivity cell.
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Affiliation(s)
- Brandi D. Sanders
- Department of Chemistry, Bucknell University, Lewisburg, Pennsylvania 17837
| | | | | | | | - Timothy G. Strein
- Department of Chemistry, Bucknell University, Lewisburg, Pennsylvania 17837
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12
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Samoshina NM, Samoshin VV. The Michaelis constants ratio for two substrates with a series of fungal (mould and yeast) β-galactosidases. Enzyme Microb Technol 2005. [DOI: 10.1016/j.enzmictec.2004.07.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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13
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Priego-Capote F, Luque de Castro MD. Dual injection capillary electrophoresis: Foundations and applications. Electrophoresis 2004; 25:4074-85. [PMID: 15597416 DOI: 10.1002/elps.200406135] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The state of the art of capillary electrophoresis (CE) approaches based on dual injection is here reported. Dual injection strategies have been proposed with three main objectives: (i) to provide information about reaction kinetics and/or related parameters, (ii) to perform in-capillary derivatization for improving separation and/or determination, (iii) to develop electrophoretic methods for the simultaneous analysis of anionic and cationic compounds. For the first two purposes, dual injection, which involves sample and reagent, can be realized either from the same end of the capillary (electrophoretically mediated microanalysis, EMMA) or from the two ends of the capillary (electroinjection analysis, EIA). The third objective, with dual injection of sample from the two ends of the capillary, takes advantage of moving cationic and anionic compounds with opposite directions. The foundations of each alternative, conditions necessary for working with them, restrictions, applications as well as perspectives are reviewed in order to establish the advantages, shortcomings, and convenience or no of their use in comparison to conventional CE.
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Nováková S, Van Dyck S, Van Schepdael A, Hoogmartens J, Glatz Z. Electrophoretically mediated microanalysis. J Chromatogr A 2004; 1032:173-84. [PMID: 15065794 DOI: 10.1016/j.chroma.2003.12.025] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
This review describes the existing developments in the use of the capillary electrophoretic microanalytical technique for the in-line study of enzyme reaction, electrophoretically mediated microanalysis (EMMA). The article is divided into a number of parts. After an introduction, the different modes, basic principle, procedure, and some mathematical treatments of EMMA methodology are discussed and illustrated. The applications of EMMA for enzyme assay and for non-enzymatic determination are summarized into two tables. In addition to classical capillary electrophoresis (CE) instrument EMMA, special emphasis is given to a relatively new technique: EMMA on CE microchip. Finally, conclusions are drawn.
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Affiliation(s)
- Sona Nováková
- Laboratory for Pharmaceutical Chemistry and Drug Analysis, Faculty of Pharmaceutical Sciences, K. U. Leuven, Van Evenstraat 4, B-3000 Leuven, Belgium
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