1
|
Lopez V, Schuh HJM, Mirza S, Vaaßen VJ, Schmidt MS, Sylvester K, Idris RM, Renn C, Schäkel L, Pelletier J, Sévigny J, Naggi A, Scheffler B, Lee SY, Bendas G, Müller CE. Heparins are potent inhibitors of ectonucleotide pyrophosphatase/phospho-diesterase-1 (NPP1) - a promising target for the immunotherapy of cancer. Front Immunol 2023; 14:1173634. [PMID: 37711611 PMCID: PMC10497752 DOI: 10.3389/fimmu.2023.1173634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Accepted: 07/03/2023] [Indexed: 09/16/2023] Open
Abstract
Introduction Heparins, naturally occurring glycosaminoglycans, are widely used for thrombosis prevention. Upon application as anticoagulants in cancer patients, heparins were found to possess additional antitumor activities. Ectonucleotidases have recently been proposed as novel targets for cancer immunotherapy. Methods and results In the present study, we discovered that heparin and its derivatives act as potent, selective, allosteric inhibitors of the poorly investigated ectonucleotidase NPP1 (nucleotide pyrophosphatase/phosphodiesterase-1, CD203a). Structure-activity relationships indicated that NPP1 inhibition could be separated from the compounds' antithrombotic effect. Moreover, unfractionated heparin (UFH) and different low molecular weight heparins (LMWHs) inhibited extracellular adenosine production by the NPP1-expressing glioma cell line U87 at therapeutically relevant concentrations. As a consequence, heparins inhibited the ability of U87 cell supernatants to induce CD4+ T cell differentiation into immunosuppressive Treg cells. Discussion NPP1 inhibition likely contributes to the anti-cancer effects of heparins, and their specific optimization may lead to improved therapeutics for the immunotherapy of cancer.
Collapse
Affiliation(s)
- Vittoria Lopez
- Pharmaceutical Institute, Pharmaceutical and Medicinal Chemistry, University of Bonn, Bonn, Germany
- PharmaCenter Bonn, University of Bonn, Bonn, Germany
| | - H. J. Maximilian Schuh
- Pharmaceutical Institute, Pharmaceutical and Cell Biological Chemistry, University of Bonn, Bonn, Germany
| | - Salahuddin Mirza
- Pharmaceutical Institute, Pharmaceutical and Medicinal Chemistry, University of Bonn, Bonn, Germany
- PharmaCenter Bonn, University of Bonn, Bonn, Germany
| | - Victoria J. Vaaßen
- Pharmaceutical Institute, Pharmaceutical and Medicinal Chemistry, University of Bonn, Bonn, Germany
- PharmaCenter Bonn, University of Bonn, Bonn, Germany
| | - Michael S. Schmidt
- Pharmaceutical Institute, Pharmaceutical and Cell Biological Chemistry, University of Bonn, Bonn, Germany
| | - Katharina Sylvester
- Pharmaceutical Institute, Pharmaceutical and Medicinal Chemistry, University of Bonn, Bonn, Germany
- PharmaCenter Bonn, University of Bonn, Bonn, Germany
| | - Riham M. Idris
- Pharmaceutical Institute, Pharmaceutical and Medicinal Chemistry, University of Bonn, Bonn, Germany
- PharmaCenter Bonn, University of Bonn, Bonn, Germany
| | - Christian Renn
- Pharmaceutical Institute, Pharmaceutical and Medicinal Chemistry, University of Bonn, Bonn, Germany
- PharmaCenter Bonn, University of Bonn, Bonn, Germany
| | - Laura Schäkel
- Pharmaceutical Institute, Pharmaceutical and Medicinal Chemistry, University of Bonn, Bonn, Germany
- PharmaCenter Bonn, University of Bonn, Bonn, Germany
| | - Julie Pelletier
- Centre de Recherche du CHU de Québec-Université Laval, Québec, QC, Canada
| | - Jean Sévigny
- Centre de Recherche du CHU de Québec-Université Laval, Québec, QC, Canada
- Départment de Microbiologie-Infectiologie et d’Immunologie, Faculté de Médecine, Université Laval, Quebec, QC, Canada
| | - Annamaria Naggi
- Institute for Chemical and Biochemical Research “G. Ronzoni”, Milan, Italy
| | - Björn Scheffler
- DKFZ Division Translational Neurooncology at the West German Cancer Center (WTZ), DKTK Partner site, University Hospital Essen and German Cancer Research Center, Heidelberg, Germany
| | - Sang-Yong Lee
- Pharmaceutical Institute, Pharmaceutical and Medicinal Chemistry, University of Bonn, Bonn, Germany
- PharmaCenter Bonn, University of Bonn, Bonn, Germany
| | - Gerd Bendas
- Pharmaceutical Institute, Pharmaceutical and Cell Biological Chemistry, University of Bonn, Bonn, Germany
| | - Christa E. Müller
- Pharmaceutical Institute, Pharmaceutical and Medicinal Chemistry, University of Bonn, Bonn, Germany
- PharmaCenter Bonn, University of Bonn, Bonn, Germany
| |
Collapse
|
2
|
Schäkel L, Mirza S, Winzer R, Lopez V, Idris R, Al-Hroub H, Pelletier J, Sévigny J, Tolosa E, Müller CE. Protein kinase inhibitor ceritinib blocks ectonucleotidase CD39 - a promising target for cancer immunotherapy. J Immunother Cancer 2022; 10:jitc-2022-004660. [PMID: 35981785 PMCID: PMC9394215 DOI: 10.1136/jitc-2022-004660] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/24/2022] [Indexed: 11/08/2022] Open
Abstract
Background An important mechanism, by which cancer cells achieve immune escape, is the release of extracellular adenosine into their microenvironment. Adenosine activates adenosine A2A and A2B receptors on immune cells constituting one of the strongest immunosuppressive mediators. In addition, extracellular adenosine promotes angiogenesis, tumor cell proliferation, and metastasis. Cancer cells upregulate ectonucleotidases, most importantly CD39 and CD73, which catalyze the hydrolysis of extracellular ATP to AMP (CD39) and further to adenosine (CD73). Inhibition of CD39 is thus expected to be an effective strategy for the (immuno)therapy of cancer. However, suitable small molecule inhibitors for CD39 are not available. Our aim was to identify drug-like CD39 inhibitors and evaluate them in vitro. Methods We pursued a repurposing approach by screening a self-compiled collection of approved, mostly ATP-competitive protein kinase inhibitors, on human CD39. The best hit compound was further characterized and evaluated in various orthogonal assays and enzyme preparations, and on human immune and cancer cells. Results The tyrosine kinase inhibitor ceritinib, a potent anticancer drug used for the treatment of anaplastic lymphoma kinase (ALK)-positive metastatic non-small cell lung cancer, was found to strongly inhibit CD39 showing selectivity versus other ectonucleotidases. The drug displays a non-competitive, allosteric mechanism of CD39 inhibition exhibiting potency in the low micromolar range, which is independent of substrate (ATP) concentration. We could show that ceritinib inhibits ATP dephosphorylation in peripheral blood mononuclear cells in a dose-dependent manner, resulting in a significant increase in ATP concentrations and preventing adenosine formation from ATP. Importantly, ceritinib (1–10 µM) substantially inhibited ATP hydrolysis in triple negative breast cancer and melanoma cells with high native expression of CD39. Conclusions CD39 inhibition might contribute to the effects of the powerful anticancer drug ceritinib. Ceritinib is a novel CD39 inhibitor with high metabolic stability and optimized physicochemical properties; according to our knowledge, it is the first brain-permeant CD39 inhibitor. Our discovery will provide the basis (i) to develop more potent and balanced dual CD39/ALK inhibitors, and (ii) to optimize the ceritinib scaffold towards interaction with CD39 to obtain potent and selective drug-like CD39 inhibitors for future in vivo studies.
Collapse
Affiliation(s)
- Laura Schäkel
- Pharmaceutical & Medicinal Chemistry, University of Bonn, Bonn, Germany
| | - Salahuddin Mirza
- Pharmaceutical & Medicinal Chemistry, University of Bonn, Bonn, Germany
| | - Riekje Winzer
- Immunology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Vittoria Lopez
- Pharmaceutical & Medicinal Chemistry, University of Bonn, Bonn, Germany
| | - Riham Idris
- Pharmaceutical & Medicinal Chemistry, University of Bonn, Bonn, Germany
| | - Haneen Al-Hroub
- Pharmaceutical & Medicinal Chemistry, University of Bonn, Bonn, Germany
| | - Julie Pelletier
- Centre de Recherche du CHU de Québec - Université Laval, Quebec City, Quebec, Canada
| | - Jean Sévigny
- Centre de Recherche du CHU de Québec - Université Laval, Quebec City, Quebec, Canada.,Départment de Microbiologie-Infectiologie et d'Immunologie, Faculté de Medicine, Université Laval, Quebec City, Quebec, Canada
| | - Eva Tolosa
- Immunology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Christa E Müller
- Pharmaceutical & Medicinal Chemistry, University of Bonn, Bonn, Germany
| |
Collapse
|
3
|
Lopez V, Schäkel L, Schuh HJM, Schmidt MS, Mirza S, Renn C, Pelletier J, Lee SY, Sévigny J, Alban S, Bendas G, Müller CE. Sulfated Polysaccharides from Macroalgae Are Potent Dual Inhibitors of Human ATP-Hydrolyzing Ectonucleotidases NPP1 and CD39. Mar Drugs 2021; 19:md19020051. [PMID: 33499103 PMCID: PMC7911304 DOI: 10.3390/md19020051] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 01/14/2021] [Accepted: 01/15/2021] [Indexed: 12/25/2022] Open
Abstract
Extracellular ATP mediates proinflammatory and antiproliferative effects via activation of P2 nucleotide receptors. In contrast, its metabolite, the nucleoside adenosine, is strongly immunosuppressive and enhances tumor proliferation and metastasis. The conversion of ATP to adenosine is catalyzed by ectonucleotidases, which are expressed on immune cells and typically upregulated on tumor cells. In the present study, we identified sulfopolysaccharides from brown and red sea algae to act as potent dual inhibitors of the main ATP-hydrolyzing ectoenzymes, ectonucleotide pyrophosphatase/phosphodiesterase-1 (NPP1) and ecto-nucleoside triphosphate diphosphohydrolase-1 (NTPDase1, CD39), showing nano- to picomolar potency and displaying a non-competitive mechanism of inhibition. We showed that one of the sulfopolysaccharides tested as a representative example reduced adenosine formation at the surface of the human glioblastoma cell line U87 in a concentration-dependent manner. These natural products represent the most potent inhibitors of extracellular ATP hydrolysis known to date and have potential as novel therapeutics for the immunotherapy of cancer.
Collapse
Affiliation(s)
- Vittoria Lopez
- Pharmaceutical & Medicinal Chemistry, Pharmaceutical Institute, University of Bonn, An der Immenburg 4, 53121 Bonn, Germany; (V.L.); (L.S.); (S.M.); (C.R.); (S.-Y.L.)
- PharmaCenter Bonn, University of Bonn, An der Immenburg 4, 53121 Bonn, Germany
| | - Laura Schäkel
- Pharmaceutical & Medicinal Chemistry, Pharmaceutical Institute, University of Bonn, An der Immenburg 4, 53121 Bonn, Germany; (V.L.); (L.S.); (S.M.); (C.R.); (S.-Y.L.)
- PharmaCenter Bonn, University of Bonn, An der Immenburg 4, 53121 Bonn, Germany
| | - H. J. Maximilian Schuh
- Pharmaceutical & Cell Biological Chemistry, Pharmaceutical Institute, University of Bonn, An der Immenburg 4, 53121 Bonn, Germany; (H.J.M.S.); (M.S.S.); (G.B.)
| | - Michael S. Schmidt
- Pharmaceutical & Cell Biological Chemistry, Pharmaceutical Institute, University of Bonn, An der Immenburg 4, 53121 Bonn, Germany; (H.J.M.S.); (M.S.S.); (G.B.)
| | - Salahuddin Mirza
- Pharmaceutical & Medicinal Chemistry, Pharmaceutical Institute, University of Bonn, An der Immenburg 4, 53121 Bonn, Germany; (V.L.); (L.S.); (S.M.); (C.R.); (S.-Y.L.)
- PharmaCenter Bonn, University of Bonn, An der Immenburg 4, 53121 Bonn, Germany
| | - Christian Renn
- Pharmaceutical & Medicinal Chemistry, Pharmaceutical Institute, University of Bonn, An der Immenburg 4, 53121 Bonn, Germany; (V.L.); (L.S.); (S.M.); (C.R.); (S.-Y.L.)
- PharmaCenter Bonn, University of Bonn, An der Immenburg 4, 53121 Bonn, Germany
| | - Julie Pelletier
- Centre de Recherche du CHU de Québec—Université Laval, Québec City, QC G1V 4G2, Canada; (J.P.); (J.S.)
| | - Sang-Yong Lee
- Pharmaceutical & Medicinal Chemistry, Pharmaceutical Institute, University of Bonn, An der Immenburg 4, 53121 Bonn, Germany; (V.L.); (L.S.); (S.M.); (C.R.); (S.-Y.L.)
- PharmaCenter Bonn, University of Bonn, An der Immenburg 4, 53121 Bonn, Germany
| | - Jean Sévigny
- Centre de Recherche du CHU de Québec—Université Laval, Québec City, QC G1V 4G2, Canada; (J.P.); (J.S.)
- Départment de Microbiologie-Infectiologie et d’Immunologie, Faculté de Médecine, Université Laval, Quebec City, QC G1V 0A6, Canada
| | - Susanne Alban
- Pharmaceutical Institute, Christian-Albrechts-University of Kiel, Gutenbergstraße 76, 24118 Kiel, Germany;
| | - Gerd Bendas
- Pharmaceutical & Cell Biological Chemistry, Pharmaceutical Institute, University of Bonn, An der Immenburg 4, 53121 Bonn, Germany; (H.J.M.S.); (M.S.S.); (G.B.)
| | - Christa E. Müller
- Pharmaceutical & Medicinal Chemistry, Pharmaceutical Institute, University of Bonn, An der Immenburg 4, 53121 Bonn, Germany; (V.L.); (L.S.); (S.M.); (C.R.); (S.-Y.L.)
- PharmaCenter Bonn, University of Bonn, An der Immenburg 4, 53121 Bonn, Germany
- Correspondence: ; Tel.: +49-228-73-2301; Fax: +49-228-73-2567
| |
Collapse
|
4
|
Murana E, Pagani F, Basilico B, Sundukova M, Batti L, Di Angelantonio S, Cortese B, Grimaldi A, Francioso A, Heppenstall P, Bregestovski P, Limatola C, Ragozzino D. ATP release during cell swelling activates a Ca 2+-dependent Cl - current by autocrine mechanism in mouse hippocampal microglia. Sci Rep 2017. [PMID: 28646166 PMCID: PMC5482828 DOI: 10.1038/s41598-017-04452-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Microglia cells, resident immune cells of the brain, survey brain parenchyma by dynamically extending and retracting their processes. Cl− channels, activated in the cellular response to stretch/swelling, take part in several functions deeply connected with microglia physiology, including cell shape changes, proliferation, differentiation and migration. However, the molecular identity and functional properties of these Cl− channels are largely unknown. We investigated the properties of swelling-activated currents in microglial from acute hippocampal slices of Cx3cr1+/GFP mice by whole-cell patch-clamp and imaging techniques. The exposure of cells to a mild hypotonic medium, caused an outward rectifying current, developing in 5–10 minutes and reverting upon stimulus washout. This current, required for microglia ability to extend processes towards a damage signal, was carried mainly by Cl− ions and dependent on intracellular Ca2+. Moreover, it involved swelling-induced ATP release. We identified a purine-dependent mechanism, likely constituting an amplification pathway of current activation: under hypotonic conditions, ATP release triggered the Ca2+-dependent activation of anionic channels by autocrine purine receptors stimulation. Our study on native microglia describes for the first time the functional properties of stretch/swelling-activated currents, representing a key element in microglia ability to monitor the brain parenchyma.
Collapse
Affiliation(s)
- E Murana
- Department of Physiology and Pharmacology, Sapienza University, Rome, Italy
| | - F Pagani
- Istituto Italiano di Tecnologia, CLNS@Sapienza, Rome, Italy.
| | - B Basilico
- Department of Physiology and Pharmacology, Sapienza University, Rome, Italy
| | - M Sundukova
- Mouse Biology Unit, EMBL, Monterotondo, Italy
| | - L Batti
- Mouse Biology Unit, EMBL, Monterotondo, Italy
| | - S Di Angelantonio
- Department of Physiology and Pharmacology, Sapienza University, Rome, Italy.,Istituto Italiano di Tecnologia, CLNS@Sapienza, Rome, Italy
| | - B Cortese
- CNR NANOTEC - Istituto di Nanotecnologia, Department of Physics, University Sapienza, Rome, Italy
| | - A Grimaldi
- Istituto Italiano di Tecnologia, CLNS@Sapienza, Rome, Italy
| | - A Francioso
- Department of Biochemistry, "Sapienza" University of Rome, Rome, Italy
| | | | - P Bregestovski
- Aix Marseille University, Inserm, INS, Institut de Neurosciences des Systèmes, Marseille, France
| | - C Limatola
- IRCCS Neuromed, Via Atinese, Pozzilli, Italy.,Pasteur Institute - Department of Physiology and Pharmacology, Sapienza University, Rome, Italy
| | - D Ragozzino
- Department of Physiology and Pharmacology, Sapienza University, Rome, Italy.,IRCCS Neuromed, Via Atinese, Pozzilli, Italy
| |
Collapse
|
5
|
Fiene A, Baqi Y, Malik EM, Newton P, Li W, Lee SY, Hartland EL, Müller CE. Inhibitors for the bacterial ectonucleotidase Lp1NTPDase from Legionella pneumophila. Bioorg Med Chem 2016; 24:4363-4371. [DOI: 10.1016/j.bmc.2016.07.027] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Accepted: 07/15/2016] [Indexed: 12/29/2022]
|
6
|
Sfakianaki A, Stalikas C. Selective microextraction of mononucleotides from milk using alumina and stannia hollow fibers prior to their determination by hydrophilic interaction liquid chromatography–diode array detection. Food Chem 2015; 184:188-95. [DOI: 10.1016/j.foodchem.2015.03.074] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Revised: 01/29/2015] [Accepted: 03/21/2015] [Indexed: 11/26/2022]
|
7
|
Li W, Zech I, Gieselmann V, Müller CE. A capillary electrophoresis method with dynamic pH junction stacking for the monitoring of cerebroside sulfotransferase. J Chromatogr A 2015; 1407:222-7. [DOI: 10.1016/j.chroma.2015.06.053] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2015] [Revised: 06/16/2015] [Accepted: 06/19/2015] [Indexed: 12/27/2022]
|
8
|
Sekar R, Kailasa SK, Li WS, Wu HC, Wu HF. Rapid separation of acetophenone and its monohydroxy isomers by capillary electrophoresis. CHINESE CHEM LETT 2013. [DOI: 10.1016/j.cclet.2013.04.036] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
|
9
|
Hsieh YT, Chen WT, Chang HT. Detection of Nucleoside Monophosphates through Surface-Assisted Laser, Desorption/Ionization Mass Spectrometry Using CTAB-Adsorbed Gold, Nanoparticles. J CHIN CHEM SOC-TAIP 2011. [DOI: 10.1002/jccs.201190119] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
10
|
Ding X, Li Y, Song B, Zhao S, Wang Z. Determination of 5′-mononucleotides in infant formula by capillary electrophoresis with ultraviolet detection. ACTA ACUST UNITED AC 2011. [DOI: 10.1007/s13594-011-0035-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
|
11
|
High-sensitivity capillary electrophoresis method for monitoring purine nucleoside phosphorylase and adenosine deaminase reactions by a reversed electrode polarity switching mode. J Chromatogr A 2011; 1218:4764-71. [PMID: 21664618 DOI: 10.1016/j.chroma.2011.04.085] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2011] [Revised: 04/24/2011] [Accepted: 04/27/2011] [Indexed: 11/22/2022]
Abstract
A simple, efficient, and highly sensitive in-line CE method was developed for the characterization and for inhibition studies of the nucleoside-metabolizing enzymes purine nucleoside phosphorylase (PNP) and adenosine deaminase (ADA) present in membrane preparations of human 1539 melanoma cells. After filling the running buffer (50 mM borate buffer, 100 mM SDS, pH 9.10) into a fused-silica capillary (50 cm effective length × 75 μm), a large sample volume was loaded by hydrodynamic injection (5 psi, 36 s), followed by the removal of the large plug of sample matrix from the capillary using polarity switching (-20 kV). The current was monitored and the polarity was reversed when 95% of the current had been recovered. The separation of the neutral analytes (nucleosides and nucleobases) was performed by applying a voltage of 15 kV. An about 10-fold improvement of sensitivity for the five investigated analytes (adenosine, inosine, adenine, hypoxanthine, xanthine) was achieved by large-volume stacking with polarity switching when compared with CE without stacking. For inosine and adenine detection limits as low as 60 nM were achieved. To the best of our knowledge, this represents the highest sensitivity for nucleoside and nucleobase analysis using CE with UV detection reported so far. The Michaelis-Menten constants (K(m)) for PNP and ADA and the inhibition constants (K(i)) for standard inhibitors determined with the new method were consistent with literature data.
Collapse
|
12
|
Ranogajec A, Beluhan S, Smit Z. Analysis of nucleosides and monophosphate nucleotides from mushrooms with reversed-phase HPLC. J Sep Sci 2010; 33:1024-33. [PMID: 20175083 DOI: 10.1002/jssc.200900516] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The retention characteristics of five stationary phases were tested by using a selection of 5'-mononucleotides and nucleosides with the aim to develop a simple, rapid and sensitive reversed-phase liquid chromatography method without ion-pair reagent usage. The method was optimized by changes in temperature, pH and ionic strength on a column showing a superior performance. The mobile phase consisted of a mixture of 0.05 M phosphate buffer and methanol, delivered at a flow rate of 0.4 mL/min and based on a gradient program. UV detection was used at a 254 nm wavelength. The method was validated for a quantitative analysis of 5'-mononucleotides and nucleosides in wild edible mushrooms. For all nucleosides and nucleotides, the LOD and LOQ were less than 0.02 and 0.07 microg/mL, respectively. Validation parameters yielded recovery rates between 68.6 and 98.2%, with a precision expressed as a relative standard deviation of 7.6-15.3%. The content of 5'-mononucleotides and nucleosides was determined for 10 samples of wild edible mushrooms found in Croatia and, accordingly, the equivalent umami concentrations were calculated.
Collapse
Affiliation(s)
- Ana Ranogajec
- Laboratory for Liquid Chromatography, Institute of Public Health Dr. Andrija Stampar, Zagreb, Croatia.
| | | | | |
Collapse
|
13
|
Ross D, Kralj JG. Simple device for multiplexed electrophoretic separations using gradient elution moving boundary electrophoresis with channel current detection. Anal Chem 2009; 80:9467-74. [PMID: 19007187 DOI: 10.1021/ac801597e] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A new microfluidic electrophoresis device and technique is described that is designed specifically for multiplexed, high-throughput separations. The device consists of an array of short (3 mm) capillaries connecting individual sample reservoirs to a common buffer reservoir. Each capillary in the array functions as both a separation channel and as a conductivity-based detection cell. The new technique is based upon the recently described gradient elution moving boundary electrophoresis (GEMBE) technique, which uses a combination of an electric field and buffer counterflow to achieve electrophoretic separations in short capillaries or microfluidic channels. A high voltage drives electrophoresis of the sample analytes through each separation channel. At the start of a separation, the bulk counterflow of buffer through the channel is high, and none of the analytes of interest can enter the channel. The counterflow is then gradually reduced until each analyte, in turn, is able to enter the channel where it is detected as a moving boundary or step. With very short capillaries, only one step at a time is present in each capillary, and the electric current through the channels can then be used as the detector signal, without any extra detector hardware. The current vs time signal for each channel is then smoothed and differentiated to produce a set of simultaneous electropherograms. Because there is no light source or other added hardware required for detection, the system is simple and can be easily and inexpensively scaled up to perform large numbers of simultaneous analyses. As a first demonstration, a 16-channel array device is used for high-throughput, time-series measurements of enzyme activity and inhibition.
Collapse
Affiliation(s)
- David Ross
- Biochemical Science Division, National Institute of Standards & Technology, Gaithersburg, Maryland 20899, USA
| | | |
Collapse
|
14
|
Wang T, Kang J. Hexokinase inhibitor screening based on adenosine 5'-diphosphate determination by electrophoretically mediated microanalysis. Electrophoresis 2009; 30:1349-54. [PMID: 19306267 DOI: 10.1002/elps.200800542] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
A CE-based method for hexokinase inhibitor screening was developed in the present paper. In this method, hexokinase activity was assayed via electrophoretically mediated microanalysis (EMMA), which combines on-column hexokinase-mediated reaction and measurement of produced adenosine 5'-diphosphate (ADP) via electrophoretical separation and UV detection. Enzyme inhibition can be read out directly from the reduced peak area of ADP in comparison with a reference electropherogram obtained in the absence of any inhibitor. Conditions for on-column enzyme reaction and separation of adenosine 5'-triphosphate (ATP) and ADP were optimized. The optimal buffer composition for enzymatic reaction was 25 mM HEPES buffer (pH 7.5) containing 5 mM MgCl(2), whereas the optimal buffer composition for separation was 100 mM Tris-phosphate buffer (pH 5.5) containing 0.02% (m/v) hexadimethrine bromide (HDB). Fortunately, discontinuous buffer system can be adapted easily in the EMMA method. The time for separation was reduced dramatically to less than 3 min by reversing the direction of EOF via dynamically coating the capillary wall with the cationic polyelectrolyte HDB. Moreover, the peak tailing of ATP was also reduced by HDB coating. The Z' factor as high as 0.98 was obtained, indicating a high quality of the screening data. The present method is simple, robust and cost-effective.
Collapse
Affiliation(s)
- Tongdan Wang
- Shanghai Institute of Organic Chemistry, Chinese Academy of Science, Shanghai, PR China
| | | |
Collapse
|
15
|
Viñas P, Campillo N, López-García I, Martínez-López S, Vasallo I, Hernández-Córdoba M. Anion exchange liquid chromatography for the determination of nucleotides in baby and/or functional foods. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2009; 57:7245-7249. [PMID: 19655760 DOI: 10.1021/jf901726e] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
A sensitive, selective and solvent-free procedure is proposed for the rapid determination of monophosphate nucleotides (cytidine 5'-monophosphate, uridine 5'-monophosphate, adenosine 5'-monophosphate, and guanosine 5'-monophosphate) in baby foods. The method is based on the deproteinization of foods and direct analysis by anion exchange liquid chromatography (LC). Nucleotides were separated on an SAX anion exchange column with isocratic elution using 0.01 M dihydrogenphosphate buffer (pH 3.5) as mobile phase at a flow-rate of 1 mL min(-1) and detected by diode-array detection (DAD). The LC method rapidly separated the nucleotides (9 min) and was validated for linearity, detection and quantitation limits, selectivity, accuracy, and precision. The recoveries obtained for spiked samples were satisfactory for all the analytes. The proposed procedure allowed the only authorized nucleotides in infant formulas to be determined and was successfully applied to the analysis of different baby and/or functional food samples, including infant formulas, fermented milk, cereals, and purees.
Collapse
Affiliation(s)
- Pilar Viñas
- Departamento de Quimica Analitica, Facultad de Quimica, Universidad de Murcia, Murcia, Spain
| | | | | | | | | | | |
Collapse
|
16
|
Sauer R, El-Tayeb A, Kaulich M, Müller CE. Synthesis of uracil nucleotide analogs with a modified, acyclic ribose moiety as P2Y(2) receptor antagonists. Bioorg Med Chem 2009; 17:5071-9. [PMID: 19523835 DOI: 10.1016/j.bmc.2009.05.062] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2009] [Revised: 05/16/2009] [Accepted: 05/23/2009] [Indexed: 11/17/2022]
Abstract
A series of new uracil nucleotide analogs (monophosphates, triphosphates, and phosphonates) was synthesized, in which the ribose moiety was replaced by acyclic chains, including branched or linear alkyl or dialkylether linkers. 1-omega-Bromoalkyluracil derivatives (2) were converted to the corresponding alcohols by treatment with sodium hydroxide and subsequently phosphorylated using phosphorus oxychloride followed by hydrolysis to yield the monophosphates, or by coupling with diphosphate to form the triphosphates. Reaction of 2 with triethyl phosphite followed by deprotection with trimethylsilyl bromide led to the omega-phosphonylalkyluracil derivatives. These products could be further phosphorylated by converting them into their imidazolides and subsequent treatment with diphosphate yielding the corresponding UTP analogs. Nucleoside analogs with an oxygen atom in the 2'-position, which are more similar to the natural ribosides, were synthesized from silylated uracil and trimethylsilyl iodide-treated 1,3-dioxolane, or 1,3-dioxane, respectively, and subsequently phosphorylated by standard procedures. The nucleotide analogs were investigated in a functional assay at NG108-15 cells, a neuroblastomaxglioma hybrid cell line which expresses the UTP- and ATP-activated nucleotide receptor subtype P2Y(2). The acyclic nucleotide analogs were generally weaker ligands than UTP, and-in contrast to UTP-they were antagonistic. The most potent compound was diphosphoric 5-(2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)pentylphosphonic anhydride (5c) with an IC(50) value of 92microM showing that the replacement of the alpha-phosphate by phosphonate, which leads to enhanced stability, was well tolerated.
Collapse
Affiliation(s)
- Roland Sauer
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, D-53121 Bonn, Germany
| | | | | | | |
Collapse
|
17
|
Capillary electrophoresis-based nanoscale assays for monitoring ecto-5′-nucleotidase activity and inhibition in preparations of recombinant enzyme and melanoma cell membranes. Anal Biochem 2008; 373:129-40. [DOI: 10.1016/j.ab.2007.09.028] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2007] [Revised: 09/21/2007] [Accepted: 09/21/2007] [Indexed: 11/23/2022]
|
18
|
CE coupled with amperometric detection using a boron-doped diamond microelectrode: Validation of a method for endogenous norepinephrine analysis in tissue. Electrophoresis 2008; 29:441-7. [DOI: 10.1002/elps.200700398] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
|
19
|
Lin J, Wu X, Lin X, Xie Z. Preparation of polymethacrylate monolithic stationary phases having bonded octadecyl ligands and sulfonate groups: electrochromatographic characterization and application to the separation of polar solutes for pressurized capillary electrochromatography. J Chromatogr A 2007; 1169:220-7. [PMID: 17875313 DOI: 10.1016/j.chroma.2007.08.061] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2007] [Revised: 08/26/2007] [Accepted: 08/30/2007] [Indexed: 10/22/2022]
Abstract
In this report, the preparation of porous polymethacrylate-based monolithic columns by in situ copolymerization of octadecyl methacrylate (OMA), 3-sulfopropyl methacrylate (SPMA) and ethylene dimethacrylate (EDMA) in a binary porogenic solvent consisting of cyclohexanol/1,4-butanediol are proposed. These monoliths possess in their structures bonded octadecyl ligands and sulfonate groups and are evaluated in pressurized capillary electrochromatography (pCEC) system using small neutral and charged solutes. While the sulfonate groups are meant to generate the electroosmotic flow (EOF) necessary for transporting the mobile phase through the monolithic capillary; the octadecyl ligands are introduced to provide the nonpolar sites for chromatographic retention for neutral solutes. However, incorporating the sulfonate groups in the monoliths does not only support the EOF but also exhibit hydrophilic interaction as well as electrostatic interaction/repulsion with the monoliths in addition to electrophoretic migration with polar charged solutes (e.g., nucleotides). The monolithic stationary phases at different EOF velocities are easily prepared by altering the amount of SPMA in the polymerization solution as well as the composition of the porogenic solvent. Optimum EOF velocity, the highest efficiency and adequate chromatographic retention are obtained when 0.6% SPMA is added to the reaction mixture. Under these conditions, rapid separation and high plate counts reaching greater than 170,000 plates/m are readily obtained.
Collapse
Affiliation(s)
- Jian Lin
- Department of Chemistry, Fuzhou University, Fuzhou 350002, China
| | | | | | | |
Collapse
|
20
|
Development and application of a liquid chromatographic method for analysis of nucleotides and nucleosides in milk and infant formulas. Int Dairy J 2007. [DOI: 10.1016/j.idairyj.2006.08.001] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
|
21
|
Song J, Liu H, Han P, Zhao C, Wu Y, Zhang S. Development of a NACE method for simultaneous measurement of three adenosine monophosphate isomers in biomimicking prebiotic synthesis without sample pretreatment. Electrophoresis 2007; 27:4480-6. [PMID: 17058304 DOI: 10.1002/elps.200600164] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
A practical NACE method was developed for simultaneous determination of three adenosine monophosphate (AMP) isomers. Separation of three AMP isomers was achieved using 200 mM Tris/H(3)BO(3) in acetontrile/water (2:1 v/v) at pH* 10.0 as the running buffer and +25 kV as the applied voltage over a bare fused-silica capillary of 50 microm id x 375 microm od x 54.5 cm (46 cm to the detector window). At 260 nm, the calibration curves were linear in the range of 1-100 microg/mL. The detection limits were less than 0.70 microg/mL. The recovery ranged from 94.5 to 106.4%. The intraday RSDs of the migration times were between 2.1 and 3.0%. The developed NACE method has been successfully applied for the determination of three AMP isomers in the real samples of biomimicking prebiotic synthesis reaction between N-(O,O-diisopropyl) phosphoryl amino acid and adenosine.
Collapse
Affiliation(s)
- Juanmei Song
- Chemistry Department, Key Laboratory of Chemical Biology and Organic Chemistry of Henan, Zhengzhou University, Zhengzhou, P. R. China
| | | | | | | | | | | |
Collapse
|
22
|
Novotny M, Quaiserova-Mocko V, Wehrwein EA, Kreulen DL, Swain GM. Determination of endogenous norepinephrine levels in different chambers of the rat heart by capillary electrophoresis coupled with amperometric detection. J Neurosci Methods 2007; 163:52-9. [PMID: 17383009 PMCID: PMC2679869 DOI: 10.1016/j.jneumeth.2007.02.008] [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] [Received: 12/24/2006] [Revised: 02/12/2007] [Accepted: 02/12/2007] [Indexed: 12/27/2022]
Abstract
Capillary electrophoresis with end-column amperometric detection (CE-EC) was used to determine the regional distribution of norepinephrine (NE) in the hearts of sympathetically innervated (control) and chemically sympathectomized rats. Key features of the method are (i) the sample preparation and clean-up step that involved the application of off-line solid phase extraction (SPE) with a 95% NE recovery and (ii) the use of a diamond microelectrode for detection. NE was quantified in the left and right ventricle, the ventricular septum, and the left and right atrium. The NE concentration in the atria was three to five times higher than in the ventricles and ventricular septum of control rats. Basal NE levels in the left and right ventricle and the ventricular septum were reduced to below the detection limit (0.034 microg/g tissue) in tissues treated with the neurotoxin, 6-hydroxydopamine (6-OHDA), while only a moderate reduction was observed in the left and right atrium. Importantly, the diamond microelectrode provided low and stable background current and low peak-to-peak noise <or=0.65 pA at a detection potential of +0.86 V versus Ag/AgCl. A reproducible electrode response was observed for multiple injections of tissue homogenates with minimal response attenuation due to electrode fouling.
Collapse
Affiliation(s)
- Martin Novotny
- Department of Chemistry and the Neuroscience Program, Michigan State University, East Lansing, MI, 48824
| | - Veronika Quaiserova-Mocko
- Department of Chemistry and the Neuroscience Program, Michigan State University, East Lansing, MI, 48824
| | - Erica A. Wehrwein
- Department of Physiology and the Neuroscience Program, Michigan State University, East Lansing, MI, 48824
| | - David L. Kreulen
- Department of Physiology and the Neuroscience Program, Michigan State University, East Lansing, MI, 48824
- Corresponding authors: Greg M. Swain, Department of Chemistry, Michigan State University, 320 Chemistry Building, East Lansing, MI 48824-1322. Tel. (517) 355-9715 x229, Fax. (517)353-1793, Email. . David L. Kreulen, Department of Physiology, Michigan State University, 2201 Biomedical Physical Sciences Building, East Lansing, MI 48824-1320. Tel. (517) 355-6475 x1312, Fax. (517) 355-5125, Email.
| | - Greg M. Swain
- Department of Chemistry and the Neuroscience Program, Michigan State University, East Lansing, MI, 48824
- Corresponding authors: Greg M. Swain, Department of Chemistry, Michigan State University, 320 Chemistry Building, East Lansing, MI 48824-1322. Tel. (517) 355-9715 x229, Fax. (517)353-1793, Email. . David L. Kreulen, Department of Physiology, Michigan State University, 2201 Biomedical Physical Sciences Building, East Lansing, MI 48824-1320. Tel. (517) 355-6475 x1312, Fax. (517) 355-5125, Email.
| |
Collapse
|
23
|
Iqbal J, Scapozza L, Folkers G, Müller CE. Development and validation of a capillary electrophoresis method for the characterization of herpes simplex virus type 1 (HSV-1) thymidine kinase substrates and inhibitors. J Chromatogr B Analyt Technol Biomed Life Sci 2006; 846:281-90. [PMID: 17023224 DOI: 10.1016/j.jchromb.2006.09.018] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2006] [Revised: 08/31/2006] [Accepted: 09/08/2006] [Indexed: 11/16/2022]
Abstract
A fast, convenient capillary electrophoresis (CE) method was developed for monitoring the enzymatic reaction of herpes simplex virus type 1 thymidine kinase (HSV-1 TK). The reaction was performed in a test tube followed by quantitative analysis of the products. The optimized CE conditions were as follows: polyacrylamide-coated capillary (20 cm effective length x 50 microm), electrokinetic injection for 30s, 50 mM phosphate buffer at pH 6.5, constant current of -60 microA, UV detection at 210 nm, UMP or cAMP were used as internal standards. Phosphorylated products eluted within less than 7 min. The limits of detection were 0.36 microM for dTMP and 0.86 microM for GMP. The method was used to study enzyme kinetics, and to investigate alternative substrates and inhibitors.
Collapse
Affiliation(s)
- Jamshed Iqbal
- Pharmaceutical Institute, Department of Pharmaceutical Chemistry Poppelsdorf, University of Bonn, Kreuzbergweg 26, D-53115 Bonn, Germany
| | | | | | | |
Collapse
|
24
|
Shackman JG, Munson MS, Kan CW, Ross D. Quantitative temperature gradient focusing performed using background electrolytes at various pH values. Electrophoresis 2006; 27:3420-7. [PMID: 16944457 DOI: 10.1002/elps.200600078] [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] [Indexed: 11/10/2022]
Abstract
Temperature gradient focusing (TGF) has previously been shown to be a practical technique for simultaneous concentration and separation of a variety of samples. In this paper, we demonstrate that TGF can be conducted at a wide range of pH values. Techniques for first-order prediction of the suitability of a given BGE for focusing are discussed. Buffer suitability for TGF is assessed experimentally by simultaneously concentrating and separating a pair of fluorescent analytes. One analyte is held at constant concentration for use as an internal standard while the concentration of the other dye is varied. Peak area is shown to vary linearly with the input dye concentration. A high degree of resolution (R(s) >3) of fluorescein and carboxyfluorescein, as well as for two LysoSensor-based dyes, is also observed. Foucusing and separation by TGF was successfully conducted quantitatively in BGE solutions of pH from 3.0 to 10.5.
Collapse
Affiliation(s)
- Jonathan G Shackman
- Analytical Chemistry Division, National Institute of Standards and Technology, Gaithersburg, MD 20899-8394, USA
| | | | | | | |
Collapse
|
25
|
Bellostas N, Sørensen JC, Sørensen H. Micellar electrokinetic capillary chromatography--synchronous monitoring of substrate and products in the myrosinase catalysed hydrolysis of glucosinolates. J Chromatogr A 2006; 1130:246-52. [PMID: 16806249 DOI: 10.1016/j.chroma.2006.05.079] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2006] [Revised: 05/22/2006] [Accepted: 05/29/2006] [Indexed: 11/18/2022]
Abstract
A micellar electrokinetic capillary chromatography (MECC) method has been developed for monitoring the myrosinase catalysed hydrolysis of 2-hydroxy substituted glucosinolates and the simultaneous formation of the corresponding degradation products (oxazolidine-2-thiones (OZTs) and nitriles). Glucosibarin ((2R)-2-hydroxy-2-phenylethylglucosinolate) was chosen as the model glucosinolate owing to the difficulties in determining hydrolysis rates of this type of substrates in traditional UV-assays. The method was afterwards validated with glucobarbarin ((2S)-2-hydroxy-2-phenylethylglucosinolate) and progoitrin ((2R)-2-hydroxybut-3-enylglucosinolate). Aromatic glucosinolates without a 2-hydroxy group in their side chains, such as glucotropaeolin (benzylglucosinolate) and gluconasturtiin (phenethylglucosinolate) were also tested. Formation of the glucosinolate hydrolysis products was monitored simultaneously at 206 nm and 230 nm. This allowed estimation of the extinction coefficient of the OZT derived from glucosibarin, which was found to be 18,000 M(-1) cm(-1) and 12,000 M(-1) cm(-1) at 206 nm and 230 nm, respectively. The developed method has limit of detection of 0.04 mM and 0.06 mM and limit of quantification of 0.2 mM and 0.3 mM for the glucosibarin derived OZT and nitrile, respectively. Linearity of the glucosinolate concentration was examined at six concentration levels from 2.5 mM to 100 mM and at 206 nm a straight line (R(2)=0.9996) was obtained. The number of theoretical plates (N) at the optimal system conditions was 245,000 for the intact glucosibarin, 264,000 for the OZT and 252,000 for the nitrile.
Collapse
Affiliation(s)
- Natalia Bellostas
- Department of Natural Sciences, Biochemistry and Natural Product Chemistry, The Royal Veterinary and Agricultural University, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark
| | | | | |
Collapse
|
26
|
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.
Collapse
Affiliation(s)
- Jamshed Iqbal
- Department of Pharmaceutical Chemistry Poppelsdorf, Pharmaceutical Institute, University of Bonn, Bonn, Germany
| | | | | |
Collapse
|
27
|
Invited Lectures : Overviews Purinergic signalling: past, present and future. Purinergic Signal 2006; 2:1-324. [PMID: 18404494 PMCID: PMC2096525 DOI: 10.1007/s11302-006-9006-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/02/2006] [Indexed: 12/11/2022] Open
|
28
|
A capillary electrophoresis method for the characterization of ecto-nucleoside triphosphate diphosphohydrolases (NTPDases) and the analysis of inhibitors by in-capillary enzymatic microreaction. Purinergic Signal 2005; 1:349-58. [PMID: 18404519 PMCID: PMC2096555 DOI: 10.1007/s11302-005-8076-x] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2005] [Revised: 03/23/2005] [Accepted: 03/24/2005] [Indexed: 10/25/2022] Open
Abstract
A capillary electrophoresis (CE) method for the characterization of recombinant NTPDases 1, 2, and 3, and for assaying NTPDase inhibitors has been developed performing the enzymatic reaction within the capillary. After hydrodynamic injection of plugs of substrate solution with or without inhibitor in reaction buffer, followed by a suspension of an enzyme-containing membrane preparation, and subsequent injection of another plug of substrate solution with or without inhibitor, the reaction took place close to the capillary inlet. After 5 min, the electrophoretic separation of the reaction products was initiated by applying a constant current of -60 muA. The method employing a polyacrylamide-coated capillary and reverse polarity mode provided baseline resolution of substrates and products within a short separation time of less than 7 min. A 50 mM phosphate buffer (pH 6.5) was used for the separations and the products were detected by their UV absorbance at 210 nm. The Michaelis-Menten constants (K (m)) for the recombinant rat NTPDases 1, 2, and 3 obtained with this method were consistent with previously reported data. The inhibition studies revealed pronounced differences in the potency of reactive blue 2, pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid (PPADS), suramin, and N (6)-diethyl-beta,gamma-dibromomethylene-ATP (ARL67156) towards the NTPDase isoforms. Notably, ARL67156 does not inhibit all NTPDases, having only a minor inhibitory effect on NTPDase2. Dipyridamole is not an inhibitor of the NTPDase isoforms investigated. The new method is fast and accurate, it requires only tiny amounts of material (nanoliter scale), no sample pretreatment and can be fully automated; thus it is clearly superior to the current standard methods.
Collapse
|
29
|
Hillebrand S, Garcia W, Delmar Cantú M, de Araújo APU, Tanaka M, Tanaka T, Garratt RC, Carrilho E. In vitro monitoring of GTPase activity and enzyme kinetics studies using capillary electrophoresis. Anal Bioanal Chem 2005; 383:92-7. [PMID: 16041603 DOI: 10.1007/s00216-005-3375-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2005] [Revised: 05/21/2005] [Accepted: 06/01/2005] [Indexed: 11/25/2022]
Abstract
A capillary electrophoresis (CE)-based method for the in vitro detection and monitoring of nucleotide-triphosphatase activity is described. This robust and reproducible method was used to investigate GTPase activity of a recombinant protein construct containing the catalytic domain of Human SEPT4/Bradeion beta (GST-rDGTPase). This example application demonstrates that the CE technique can replace classical radioactive methods for GTPase activity assays and may be used as a routine analytical tool. Enzyme kinetics of GST-rDGTPase was studied and yielded the following kinetic parameters: v(max) = 1.7 microM min(-1) +/- 0.1, Km = 1.0 mM +/- 0.3, and apKcat = 9 x 10(-3) s(-1). In addition the effect of co-factors such as Mg2+ and Mn2+ on the catalytic activity was investigated. The described analytical method was also shown to be useful to analyze diphosphated and triphosphated forms of other nucleotides.
Collapse
Affiliation(s)
- Sandro Hillebrand
- Centro de Biotecnologia Molecular e Estrutural, Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, SP, Brazil
| | | | | | | | | | | | | | | |
Collapse
|
30
|
Kulp M, Kaljurand M. On-line monitoring of enzymatic conversion of adenosine triphosphate to adenosine diphosphate by micellar electrokinetic chromatography. J Chromatogr A 2004; 1032:305-12. [PMID: 15065809 DOI: 10.1016/j.chroma.2003.09.031] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Capillary electrophoresis can be a valuable tool for the on-line monitoring of bioprocesses. The enzymatic conversion of nucleotide adenosine triphosphate (ATP) to adenosine diphosphate (ADP) by hexokinase (HK) was monitored in the bioreactor interfaced by a laboratory-built microsampler to a capillary electrophoresis unit. The use of this specially designed sampling device enabled rapid consecutive injections to be performed without high-voltage (HV) interruptions. No additional sample preparation was required. The method of micellar electrokinetic chromatography, employing reversed electroosmotic flow (EOF) by cationic surfactant and reversed polarity mode provided a good resolution and short analysis time of less than 5 min. The samples were injected electrokinetically, using -25 kV voltage for 3 s and detected by their UV absorbance at 254 nm. The analytes were detected at a microg/ml level with a reproducibility of about 7%. To demonstrate the potential of CE in understanding the processes of biological interest, such as nucleotide degradation and metabolism, the investigation of the efficiency and the time course of the enzymatic transformation was carried out.
Collapse
Affiliation(s)
- Maria Kulp
- Faculty of Science, Tallinn Technical University, Ehitajate Tee 5, 19086 Tallinn, Estonia.
| | | |
Collapse
|
31
|
Pojoga LH, Haghiac ML, Moose JE, Hilderman RH. Determination of ATP impurity in adenine dinucleotides. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2004; 23:581-98. [PMID: 15113025 DOI: 10.1081/ncn-120030716] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Adenine dinucleotides (ApnA) are extracellular signal molecules that are released from blood platelets, following stress, into the vascular system. The most abundant and best-characterized ApnA (Ap4A) interacts with a unique receptor on bovine aortic endothelial cells (BAEC) where it induces nitric oxide. Ap4A also interacts with P2 purinoceptors on BAEC to modulate Ca2+ mobilization and prostacyclin release; this behavior can be equally well explained by Ap4A being either a partial agonist to these receptors, or an antagonist in the presence of ATP contamination. To discern between these two possibilities, we have investigated the presence of such contaminants in ApnA preparations. The studies herein indicate that ApnAs (n = 3-6) contain ATP impurities; thus, when characterizing the ApnA interaction with ATP-binding sites, investigators must assure that the response elicited is not partly due to an ATP impurity. We here provide a means for detecting and estimating ATP impurities within Ap4A preparations while also eliminating them; the level of this contamination is estimated to be as low as 0.2%. We applied our method to distinguish the true effect of Ap4A at P2 purinoceptors; our findings are consistent with Ap4A acting as a partial agonist to these receptors. We also applied our method to characterizing the ApnA interaction with luciferase, and found that decontaminated ApnA (n = 4-6) are weak substrates for luciferase.
Collapse
Affiliation(s)
- Luminita H Pojoga
- Department of Genetics and Biochemistry, Clemson University, Clemson, South Carolina 29634-0324, USA
| | | | | | | |
Collapse
|
32
|
Kaulich M, Qurishi R, Müller CE. Extracellular metabolism of nucleotides in neuroblastoma x glioma NG108-15 cells determined by capillary electrophoresis. Cell Mol Neurobiol 2003; 23:349-64. [PMID: 12825832 DOI: 10.1023/a:1023640721630] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
1. The metabolism of extracellular nucleotides in NG108-15 cells, a neuroblastoma x glioma hybrid cell line, was studied by means of capillary zone electrophoresis (CZE) and micellar electrokinetic capillary chromatography (MECC). 2. In NG108-15 cells ATP, ADP, AMP, UTP, UDP, and UMP were hydrolyzed to the nucleosides adenosine and uridine indicating the presence of ecto-nucleotidases and ectophosphatases. The hydrolysis of the purine nucleotides ATP and ADP was significantly faster than the hydrolysis of the pyrimidine nucleotides UTP and UDP. 3. ATP and UTP breakdown appeared to be mainly due to an ecto-nucleotide-diphosphohydrolase. ADP, but not UDP, was initially also phosphorylated to some extent to the corresponding triphosphate, indicating the presence of an adenylate kinase on NG108-15 cells. The alkaline phosphatase (ALP) inhibitor levamisole did not only inhibit the hydrolysis of AMP to adenosine and of UMP to uridine, but also the degradation of ADP and to a larger extent that of UDP. ATP and UTP degradation was only slightly inhibited by levamisole. 4. These results underscore the important role of ecto-alkaline phosphatase in the metabolism of adenine as well as uracil nucleotides in NG108-15 cells Dipyridamole, a potent inhibitor of nucleotide breakdown in superior cervical ganglion cells, had no effect on nucleotide degradation in NG108-15 cells. 5. Dipyridamole, which is a therapeutically used nucleoside reuptake inhibitor in humans, reduced the extracellular adenosine accumulation possibly by allosteric enhancement of adenosine reuptake into the cells.
Collapse
Affiliation(s)
- Marko Kaulich
- Department of Pharmaceutical Chemistry Poppelsdorf, Pharmaceutical Institute, University of Bonn, Bonn, Germany
| | | | | |
Collapse
|
33
|
Kaulich M, Streicher F, Mayer R, Müller I, Müller CE. Flavonoids - novel lead compounds for the development of P2Y2receptor antagonists. Drug Dev Res 2003. [DOI: 10.1002/ddr.10203] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
34
|
Rapid separation of nucleosides by capillary electrochromatography with a methacrylate-based monolithic stationary phase. Chromatographia 2003. [DOI: 10.1007/bf02491740] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
35
|
Markuszewski MJ, Britz-McKibbin P, Terabe S, Matsuda K, Nishioka T. Determination of pyridine and adenine nucleotide metabolites in Bacillus subtilis cell extract by sweeping borate complexation capillary electrophoresis. J Chromatogr A 2003; 989:293-301. [PMID: 12650262 DOI: 10.1016/s0021-9673(03)00031-1] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
With a growing interest in new areas of bioanalytical research such as metabolome analysis, the development of sensitive capillary electrophoresis (CE) methods to analyze sub-microM concentrations of analytes in biological samples is required. In this report, the application of CE with sweeping by borate complexation is used to analyze a group of seven pyridine and adenine nucleotide metabolites derived from bacteria Bacillus subtilis cell extracts. Nanomolar (nM) detectability of analytes by CE with UV photometric detection is achieved through effective focusing of large sample plug (approximately 10% of capillary length) using sweeping by borate complexation method, reflected by a limit of detections (S/N = 3) of about 2 x 10(-8) M. Changes in metabolites concentrations were observed in cell extracts when using either glucose or malate as the carbon source in the culture medium. Concentration of pyridine and adenine nucleotides in cell extracts varied widely from 78.6 (+/-7.6) microM for nicotinamide-adenine dinucleotide in malate to 0.66 (+/-0.12) microM for nicotinamide-adenine dinucleotide phosphate in glucose culture medium. Concentrations of metabolites in a single cell were also estimated at millimolar (mM) level. The method was validated in terms of linearity, sensitivity and reproducibility. The application of CE by sweeping borate complexation allows for sensitive and reproducible analyses of nucleotide metabolites in complex biological samples such as bacteria cell extracts.
Collapse
Affiliation(s)
- Michał Jan Markuszewski
- Graduate School of Science, Himeji Institute of Technology, Kamigori, Hyogo 678-1297, Japan.
| | | | | | | | | |
Collapse
|
36
|
Wu CC, Wu RG, Huang JG, Lin YC, Hsien-Chang C. Three-electrode electrochemical detector and platinum film decoupler integrated with a capillary electrophoresis microchip for amperometric detection. Anal Chem 2003; 75:947-52. [PMID: 12622389 DOI: 10.1021/ac025912t] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This article demonstrates that a three-electrode electrochemical (EC) detector and an electric decoupler could be fabricated in the same glass chip and integrated with an O2-plasma-treated PDMS layer using microfabrication techniques to form the capillary electrophoresis (CE) microchip. The platinized decoupler could mostly decouple the electrochemical detection circuit from the interference of an separation electric field in 10 mM 2-(N-morpholino)ethanesulfonic acid (MES, pH 6.5) solution. The baseline offset of background current recorded from the working electrode with and without application of a separation electric field was maintained at less than 0.05 pA in 10 mM MES. In addition, the platinized pseudoreference electrode was demonstrated to offer a stable potential in electrochemical detection. As a consequence, the limit of detection of dopamine was 0.125 microM at a S/N = 4. The responses for dopamine to different concentrations were found to be linear between 0.25 and 50 microM with a correlation coefficient of 0.9974 and a sensitivity of 11.76 pA/microM. The totally integrated CE-EC microchip should be able to fulfill the ideal of miniaturization and commercialization.
Collapse
Affiliation(s)
- Ching-Chou Wu
- Institute of Biomedical Engineering and Institute of Engineering Science, National Cheng Kung University, No. 1 Ta-Hseuh Road, Tainan, Taiwan 70101
| | | | | | | | | |
Collapse
|