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Hernychova L, Alexandri E, Tzakos AG, Zatloukalová M, Primikyri A, Gerothanassis IP, Uhrik L, Šebela M, Kopečný D, Jedinák L, Vacek J. Serum albumin as a primary non-covalent binding protein for nitro-oleic acid. Int J Biol Macromol 2022; 203:116-129. [PMID: 35063491 DOI: 10.1016/j.ijbiomac.2022.01.050] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 12/25/2021] [Accepted: 01/08/2022] [Indexed: 12/19/2022]
Abstract
This work explores the interaction of 9/10-nitro-oleic acid (NO2-OA) with human serum albumin (HSA). The molecular mechanism of the biological action of NO2-OA is to our knowledge based on a reversible covalent reaction-Michael addition of nucleophilic amino acid residues of proteins. Since HSA is an important fatty acid transporter, a key question is whether NO2-OA can bind covalently or non-covalently to HSA, similarly to oleic acid (OA), which can interact with the FA1-FA7 binding sites of the HSA molecule. 1H NMR studies and competition analysis with OA and the drugs ibuprofen and warfarin were used to investigate a potential non-covalent binding mode. NO2-OA/HSA binding was confirmed to compete with warfarin for FA-7 with significantly higher affinity. NO2-OA competes with ibuprofen for FA-3 and FA-6, however, in contrast to the situation with warfarin, the binding affinities are not significantly different. The described interactions are based exclusively on non-covalent binding. No covalent binding of NO2-OA to HSA was detected by MS/MS. More detailed studies based on MALDI-TOF-MS and Ellman's assay indicated that HSA can be covalently modified in the presence of NO2-OA to a very limited extent. It was also shown that NO2-OA has a higher affinity to HSA than that of OA.
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Affiliation(s)
- Lenka Hernychova
- Research Centre for Applied Molecular Oncology, Masaryk Memorial Cancer Institute, Žlutý kopec 7, Brno 656 53, Czech Republic
| | - Eleni Alexandri
- Section of Organic Chemistry and Biochemistry, Department of Chemistry, University of Ioannina, Ioannina 451 10, Greece
| | - Andreas G Tzakos
- Section of Organic Chemistry and Biochemistry, Department of Chemistry, University of Ioannina, Ioannina 451 10, Greece; Institute of Materials Science and Computing, University Research Center of Ioannina (URCI), 451 10 Ioannina, Greece
| | - Martina Zatloukalová
- Department of Medical Chemistry and Biochemistry, Faculty of Medicine and Dentistry, Palacký University, Hněvotínská 3, Olomouc 775 15, Czech Republic
| | - Alexandra Primikyri
- Section of Organic Chemistry and Biochemistry, Department of Chemistry, University of Ioannina, Ioannina 451 10, Greece
| | - Ioannis P Gerothanassis
- Section of Organic Chemistry and Biochemistry, Department of Chemistry, University of Ioannina, Ioannina 451 10, Greece
| | - Lukas Uhrik
- Research Centre for Applied Molecular Oncology, Masaryk Memorial Cancer Institute, Žlutý kopec 7, Brno 656 53, Czech Republic
| | - Marek Šebela
- Department of Biochemistry, Faculty of Science, Palacký University, Šlechtitelů 27, Olomouc 783 71, Czech Republic
| | - David Kopečný
- Department of Experimental Biology, Faculty of Science, Palacký University, Šlechtitelů 27, Olomouc 783 71, Czech Republic
| | - Lukáš Jedinák
- Department of Organic Chemistry, Faculty of Science, Palacký University, 17. listopadu 12, Olomouc 771 46, Czech Republic
| | - Jan Vacek
- Department of Medical Chemistry and Biochemistry, Faculty of Medicine and Dentistry, Palacký University, Hněvotínská 3, Olomouc 775 15, Czech Republic; The Czech Academy of Sciences, Institute of Biophysics, Královopolská 135, Brno 612 65, Czech Republic.
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Novák D, Vrba J, Zatloukalová M, Roubalová L, Stolarczyk K, Dorčák V, Vacek J. Cysteamine assay for the evaluation of bioactive electrophiles. Free Radic Biol Med 2021; 164:381-389. [PMID: 33429019 DOI: 10.1016/j.freeradbiomed.2021.01.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Revised: 01/04/2021] [Accepted: 01/05/2021] [Indexed: 11/20/2022]
Abstract
Covalent modifications of thiol and amine groups may control the function of proteins involved in the regulatory and signaling pathways of the cell. In this study, we developed a simple cysteamine assay which can be used to study the reactivity of electrophilic compounds towards primary amine and thiol groups in an aqueous environment. The detection principle is based on the electrochemical, photometrical and mass spectrometric analyses of cysteamine (2-aminoethanethiol) as the molecular probe. This technique is useful for studying the reaction kinetics of electrophiles with thiol (SH) and amino (NH2) groups. The decrease in analytical responses of cysteamine was monitored to evaluate the reactivity of three electrophilic activators of the Nrf2 pathway, which mediates the cellular stress response. The SH-reactivity under cell-free conditions of the tested electrophiles decreased in the following order: 4-hydroxy-2-nonenal ≥ nitro-oleic acid > sulforaphane. However, as shown in RAW264.7 cells, the tested compounds activated Nrf2-dependent gene expression in the opposite order: sulforaphane > nitro-oleic acid ≥ 4-hydroxy-2-nonenal. Although other factors in addition to chemical reactivity play a role in biological systems, we conclude that this cysteamine assay is a useful tool for screening potentially bioactive electrophiles and for studying their reactivity at a molecular level.
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Affiliation(s)
- David Novák
- Department of Medical Chemistry and Biochemistry, Faculty of Medicine and Dentistry, Palacky University, Hnevotinska 3, Olomouc, 77515, Czech Republic
| | - Jiří Vrba
- Department of Medical Chemistry and Biochemistry, Faculty of Medicine and Dentistry, Palacky University, Hnevotinska 3, Olomouc, 77515, Czech Republic.
| | - Martina Zatloukalová
- Department of Medical Chemistry and Biochemistry, Faculty of Medicine and Dentistry, Palacky University, Hnevotinska 3, Olomouc, 77515, Czech Republic
| | - Lenka Roubalová
- Department of Medical Chemistry and Biochemistry, Faculty of Medicine and Dentistry, Palacky University, Hnevotinska 3, Olomouc, 77515, Czech Republic
| | - Krzysztof Stolarczyk
- Department of Medical Chemistry and Biochemistry, Faculty of Medicine and Dentistry, Palacky University, Hnevotinska 3, Olomouc, 77515, Czech Republic; Faculty of Chemistry, University of Warsaw, 1 Pasteura Street, 02-093, Warsaw, Poland
| | - Vlastimil Dorčák
- The Czech Academy of Sciences, Institute of Biophysics, Kralovopolska 135, Brno, 612 65, Czech Republic
| | - Jan Vacek
- Department of Medical Chemistry and Biochemistry, Faculty of Medicine and Dentistry, Palacky University, Hnevotinska 3, Olomouc, 77515, Czech Republic; The Czech Academy of Sciences, Institute of Biophysics, Kralovopolska 135, Brno, 612 65, Czech Republic.
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Rose JC, Gehlen DB, Haraszti T, Köhler J, Licht CJ, De Laporte L. Biofunctionalized aligned microgels provide 3D cell guidance to mimic complex tissue matrices. Biomaterials 2018; 163:128-141. [PMID: 29459322 DOI: 10.1016/j.biomaterials.2018.02.001] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2017] [Revised: 02/01/2018] [Accepted: 02/02/2018] [Indexed: 12/27/2022]
Abstract
Natural healing is based on highly orchestrated processes, in which the extracellular matrix plays a key role. To resemble the native cell environment, we introduce an artificial extracellular matrix (aECM) with the capability to template hierarchical and anisotropic structures in situ, allowing a minimally-invasive application via injection. Synthetic, magnetically responsive, rod-shaped microgels are locally aligned and fixed by a biocompatible surrounding hydrogel, creating a hybrid anisotropic hydrogel (Anisogel), of which the physical, mechanical, and chemical properties can be tailored. The microgels are rendered cell-adhesive with GRGDS and incorporated either inside a cell-adhesive fibrin or bioinert poly(ethylene glycol) hydrogel to strongly interact with fibroblasts. GRGDS-modified microgels inside a fibrin-based Anisogel enhance fibroblast alignment and lead to a reduction in fibronectin production, indicating successful replacement of structural proteins. In addition, YAP-translocation to the nucleus increases with the concentration of microgels, indicating cellular sensing of the overall anisotropic mechanical properties of the Anisogel. For bioinert surrounding PEG hydrogels, GRGDS-microgels are required to support cell proliferation and fibronectin production. In contrast to fibroblasts, primary nerve growth is not significantly affected by the biomodification of the microgels. In conclusion, this approach opens new opportunities towards advanced and complex aECMs for tissue regeneration.
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Affiliation(s)
- Jonas C Rose
- DWI - Leibniz-Institute for Interactive Materials, Aachen, Germany
| | - David B Gehlen
- DWI - Leibniz-Institute for Interactive Materials, Aachen, Germany
| | - Tamás Haraszti
- DWI - Leibniz-Institute for Interactive Materials, Aachen, Germany
| | - Jens Köhler
- DWI - Leibniz-Institute for Interactive Materials, Aachen, Germany
| | | | - Laura De Laporte
- DWI - Leibniz-Institute for Interactive Materials, Aachen, Germany.
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Kongsong M, Songsurang K, Sangvanich P, Siralertmukul K, Muangsin N. Design, synthesis, fabrication and in vitro evalution of mucoadhesive 5-amino-2-mercaptobenzimidazole chitosan as low water soluble drug carriers. Eur J Pharm Biopharm 2014; 88:986-97. [PMID: 25229809 DOI: 10.1016/j.ejpb.2014.08.016] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2014] [Revised: 08/05/2014] [Accepted: 08/26/2014] [Indexed: 11/18/2022]
Abstract
Mucoadhesive thiolated chitosan suitable as a carrier for low water soluble drugs was designed and synthesized by conjugating 5-amino-2-mercaptobenzimidazole (MBI) using methylacrylate (MA) as the linking agent. A 14.4% degree of substitution of MA, as determined by (1)H NMR analysis, and 11.86±0.01μmol thiol groups/g of polymer, as determined by Ellman's method, was obtained. The MBI-MA-chitosan had an 11-fold stronger mucoadhesive property compared to unmodified chitosan at pH 1.2, as determined by the periodic acid: Schiff colorimetric method. Chitosan, MA-chitosan and MBI-MA-chitosan were fabricated as well-formed microspheres using electrospray ionization, including an entrapment efficiency of simvastatin (SV) of over 80% for the MBI-MA-chitosan. The mucoadhesiveness of the SV-loaded MBI-MA-CS microspheres was still higher than that for SV-loaded chitosan at pH 1.2 and 6.4. The SV-loaded MBI-MA-CS microspheres revealed a reduced burst effect and an increased release rate (more than fivefold higher than pure SV) of SV over 12h.
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Affiliation(s)
- Mullika Kongsong
- Program of Petrochemistry and Polymer Science, Faculty of Science, Chulalongkorn University, Bangkok, Thailand
| | - Kultida Songsurang
- Program of Petrochemistry and Polymer Science, Faculty of Science, Chulalongkorn University, Bangkok, Thailand
| | - Polkit Sangvanich
- Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok, Thailand
| | - Krisana Siralertmukul
- The Institute of Biotechnology and Genetic Engineering, Chulalongkorn University, Bangkok, Thailand
| | - Nongnuj Muangsin
- Biomaterials and Bioorganic Chemistry Research Group, Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok, Thailand.
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Jha N, Ramaprabhu S. Development of Au nanoparticles dispersed carbon nanotube-based biosensor for the detection of paraoxon. NANOSCALE 2010; 2:806-810. [PMID: 20648328 DOI: 10.1039/b9nr00336c] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
A disposable and sensitive biosensor has been fabricated for the detection of the organophosphorous (OP) compound paraoxon using an amperometric technique. For the measurements, gold nanoparticles dispersed on the outer surface of multiwalled carbon nanotubes (Au-MWNTs) has been used as the electrode material, as it possesses high electron transfer rates and provides large immobilization sites for the bioenzymes, which combines with the high electrocatalytic activity of MWNTs for thiocholine oxidation at low potential. Au-MWNTs have been synthesized by chemically reducing Au salt over functionalized MWNTs, and the same has been characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and high resolution transmission electron microscopic (HRTEM) techniques. The ability of the Au-MWNTs nanocomposite-based biosensor has been demonstrated to reliably measure the concentration of paraoxon in the nanomolar range.
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Affiliation(s)
- Neetu Jha
- Alternative Energy and Nanotechnology Laboratory (AENL), Nano-Functional Materials Technology Centre (NFMTC), Department of Physics, Indian Institute of Technology Madras, Chennai 600 036, India
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Ebrahimi B, Shojaosadati S, Ranaie S, Mousavi S. Optimization and evaluation of acetylcholine esterase immobilization on ceramic packing using response surface methodology. Process Biochem 2010. [DOI: 10.1016/j.procbio.2009.08.007] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Du D, Huang X, Cai J, Zhang A, Ding J, Chen S. An amperometric acetylthiocholine sensor based on immobilization of acetylcholinesterase on a multiwall carbon nanotube–cross-linked chitosan composite. Anal Bioanal Chem 2006; 387:1059-65. [PMID: 17186224 DOI: 10.1007/s00216-006-0972-6] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2006] [Revised: 10/21/2006] [Accepted: 10/30/2006] [Indexed: 10/23/2022]
Abstract
A simple method has been devised for immobilization of acetylcholinesterase (AChE)--covalent bonding to a multiwall carbon nanotube (MWNT)--cross-linked chitosan composite (CMC)-and a sensitive amperometric sensor for rapid detection of acetylthiocholine (ATCl) has been based on this. Fourier-transform infrared spectroscopy proved that the native structure of the immobilized enzyme was preserved on this chemically clean and homogeneous composite film, because of the excellent biocompatibility and non-toxicity of chitosan. Glutaraldehyde was used as cross-linker to covalently bond the AChE, and efficiently prevented leakage of the enzyme from the film. Because of the inherent conductive properties of the MWNT, the immobilized AChE had greater affinity for ATCl and excellent catalytic effect in the hydrolysis of ATCl, with a K(app)(m) value of 132 micromol L(-1), forming thiocholine, which was then oxidized to produce a detectable and rapid response. Under optimum conditions the amperometric current increased linearly with the increasing concentration of ATCl in the range 2.0-400 micromol L(-1), with a detection limit of 0.10 micromol L(-1). Fabrication reproducibility of the sensor was good and the stability was acceptable. The sensor is a promising new tool for characterization of enzyme inhibitors and for pesticide analysis. Abstract.
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Affiliation(s)
- Dan Du
- Key Laboratory of Pesticide & Chemical Biology of Ministry of Education, Central China Normal University, Wuhan, 430079, China
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Abbate C, Giorgianni C, Brecciaroli R, Giacobbe G, Costa C, Cavallari V, Albiero F, Catania S, Tringali MA, Martino LB, Abbate S. Changes induced by exposure of the human lung to glass fiber-reinforced plastic. ENVIRONMENTAL HEALTH PERSPECTIVES 2006; 114:1725-9. [PMID: 17107859 PMCID: PMC1665410 DOI: 10.1289/ehp.8676] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The inhalation of glass dusts mixed in resin, generally known as glass fiber-reinforced plastic (GRP), represents a little-studied occupational hazard. The few studies performed have highlighted nonspecific lung disorders in animals and in humans. In the present study we evaluated the alteration of the respiratory system and the pathogenic mechanisms causing the changes in a group of working men employed in different GRP processing operations and exposed to production dusts. The study was conducted on a sample of 29 male subjects whose mean age was 37 years and mean length of service 11 years. All of the subjects were submitted to a clinical check-up, basic tests, and bronchoalveolar lavage (BAL); microscopic studies and biochemical analysis were performed on the BAL fluid. Tests of respiratory function showed a large number of obstructive syndromes; scanning electron microscopy highlighted qualitative and quantitative alterations of the alveolar macrophages; and transmission electron microscopy revealed the presence of electron-dense cytoplasmatic inclusions indicating intense and active phlogosis (external inflammation). Biochemical analyses highlighted an increase in protein content associated with alterations of the lung oxidant/antioxidant homeostasis. Inhalation of GRP, independent of environmental concentration, causes alterations of the cellular and humoral components of pulmonary interstitium; these alterations are identified microscopically as acute alveolitis.
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Affiliation(s)
- Carmelo Abbate
- Department of Social Medicine, Section of Occupational Medicine, Messina University, Messina, Italy.
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Liu G, Riechers SL, Mellen MC, Lin Y. Sensitive electrochemical detection of enzymatically generated thiocholine at carbon nanotube modified glassy carbon electrode. Electrochem commun 2005. [DOI: 10.1016/j.elecom.2005.08.025] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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Yamada M, Marui Y, Hayashi C, Miki Y, Takemura S. New Thiocholine Ester Substrates for the Assay of Human Serum Cholinesterase. Clin Chem 2001. [DOI: 10.1093/clinchem/47.11.1962] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Abstract
Background: Several thiocholine alkanoyl esters were newly synthesized and explored as substrates for the assay of human serum cholinesterase after being subjected to the Ellman reaction (Arch Biochem Biophys 1958;74:443–50 and Arch Biochem Biophys 1959;82:70–7).
Methods: We synthesized thiocholine ester iodides by the method of Renshow et al. (J Am Chem Soc 1938;60:1765–70). We examined solubility in H2O, substrate specificity serum for cholinesterase, (spontaneous) self-hydrolysis, storage stability, and reaction conditions for measurement of the activity of the enzyme.
Results: Isobutyryl and cyclohexane-carboxyl esters showed the best efficiency for the specific and stable assay of human serum cholinesterase. Aqueous solubility of each was >10 mmol/L, and the reactivity with acetylcholinesterase was negligible. For isobutyryl and cyclohexane-carboxyl esters, respectively, spontaneous hydrolysis in the aqueous phase was ∼1/25 and ∼1/175 slower than the enzymatic hydrolysis, and assays with these substrates were linear to 1800 and 3000 U/L, respectively. The Km values of these acylthiocholines with human cholinesterase were almost equivalent (6.9 × 10−3 mmol/L). The substrates were stable in aqueous solution and in the solid state as the iodides for at least 5 years at 5 °C.
Conclusions: The isobutyrate and cyclohexane-carboxylate of thiocholine are suitable for the specific assay of human serum cholinesterase.
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Affiliation(s)
- Magohei Yamada
- International Reagents Co., Ltd., 4-3-2 Takatukadai, Nishiku, Kobe 651-2271, Japan
| | - Yoji Marui
- Laboratory for Clinical Investigation, Osaka University Hospital, 2-15 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Chozo Hayashi
- Laboratory for Clinical Investigation, Osaka University Hospital, 2-15 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Yasuyoshi Miki
- Faculty of Pharmaceutical Sciences, Kinki University, 3-4-1 Kowakae, Higashi-Osaka 577-0818, Japan
| | - Shoji Takemura
- Faculty of Pharmaceutical Sciences, Kinki University, 3-4-1 Kowakae, Higashi-Osaka 577-0818, Japan
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Barr RD, Koekebakker M, Lawson AA. Acetylcholinesterase in the human erythron. II. Biochemical assay. Am J Hematol 1988; 28:260-5. [PMID: 3166338 DOI: 10.1002/ajh.2830280409] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Acetylcholinesterase (AChE) is an integral erythrocyte membrane protein. A role for the enzyme in the developing human erythron is being explored. Assays of AchE by the standard Ellman technique overestimate the amount of enzyme by failing to account for the contribution of hemoglobin to the optical density of the reaction mixture. Furthermore, reliance on substrate selection alone for specificity is unsatisfactory. Incorporation of inhibitors of "true" AchE and of pseudocholinesterase confer greater ability to distinguish one enzyme from the other. In our experience, the inhibitor constant (Kl) for edrophonium, which is highly specific for AChE, is approximately 5 x 10(-5) M against adult human erythrocytes that contain significantly more total cholinesterase activity than do erythrocytes from umbilical cord blood. This consists of both "true" and "pseudo" enzyme, the former predominating and accounting for 0.75-1.65 (mean 1.02, median 0.87) femtomoles of substrate hydrolysed per min per cell in adult blood, with values of 0.15-1.04 (mean 0.71, median 0.73) obtained on cord blood. Moreover, the enzyme activity in neonatal erythrocytes has a rather different inhibitor profile from that of adult cells. AChE was also demonstrated in fresh (ALL) and cultured (K562 and HL60) human leukemic cells, as well as in primitive granulocyte-macrophage and erythroid cells cloned from normal human bone marrow. In the erythroid colonies the enzyme activity was 0-3.76 (mean 1.20, median 0.76) femtomoles per min per cell, apparently the first successful measurement of AChE in such cells.
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Affiliation(s)
- R D Barr
- Department of Pediatrics, Faculty of Health Sciences, McMaster University, Hamilton, Ontario, Canada
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Azemun P, Stull T, Roberts M, Smith AL. Rapid detection of chloramphenicol resistance in Haemophilus influenzae. Antimicrob Agents Chemother 1981; 20:168-70. [PMID: 6974540 PMCID: PMC181658 DOI: 10.1128/aac.20.2.168] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
We compared a rigid (1-h) screening method for the detection of chloramphenicol acetyltransferase (CAT) activity with the standard spectrophotometric CAT assay to determine whether CAT-mediated chloramphenicol resistance in Haemophilus influenzae could be determined upon primary isolation. Of 58 H. influenzae cell sonicates, 28 had detectable CAT activity when the chloramphenicol-dependent production of free coenzyme A from acetyl coenzyme A was measured spectrophotometrically (standard method). These 28 strains were identified as producing CAT by the rapid method which uses lysed cell suspensions and a color change to detect CAT. The remaining 30 strains did not have CAT activity detectable by either method. This 1-h test for CAT should prove to be useful for the early presumptive identification of chloramphenicol resistance in H. influenzae.
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