Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.1.7 (acetylcholinesterase)
28,390 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An alternative method based on thin-film conductometric microsensor is suggested for studying enzyme kinetics. It is established that the immobilized enzyme as well as soluble one is described by the classic lows of enzyme kinetics. Major parameters (Km and Vmax) are identical to those measured by the widely used methods and their amounts are 1.33 mM and 9.04 microS/min for soluble urease and 3.73 mM and 13.8 microS/min for immobilized urease; 5.26 mM and 13.9 microS/min for immobilized glucose oxidase; 13.6 mM and 122.0 microS/min for immobilized acetyl cholinesterase; 10.8 mM and 129.9 microS/min for immobilized butyryl cholinesterase. The possibility of conductometric analyzer application for detection of toxin concentration, in particular pesticides, is shown. Advantages and disadvantages of the system suggested are discussed.
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PMID:[Use of conductometric microsensors for studying kinetic parameters of enzymes]. 816 Feb 98

Amperometric sensors have been developed for hydrogen peroxide, choline, and acetylcholine by immobilization of horseradish peroxidase, (HRP), choline oxidase, and acetylcholinesterase in a cross-linked redox polymer deposited on glassy carbon electrodes. Peroxide sensors, prepared by immobilization of HRP alone, gave detection limits of 10 nM and a linear response up to ca. 1 mM. Coimmobilization of HRP and glucose oxidase was used to establish the feasibility of highly efficient bienzyme sensors at low substrate levels. Replacing glucose oxidase with choline oxidase produced sensors with submicromolar detection limits and a linear response up to 0.8 mM. Addition of acetylcholinesterase to the sensors generated a relatively small response to acetylcholine that demonstrates the feasibility of trienzyme sensors. At low substrate concentrations, no loss in sensitivity during a 1-day experiment was observed. The response times of these sensors are all less than 30 s with 2-s response times achieved in some cases.
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PMID:Amperometric sensors for peroxide, choline, and acetylcholine based on electron transfer between horseradish peroxidase and a redox polymer. 845 44

Disposable screen-printed, film carbon electrodes (PFCE) were modified with cast-coated Osmium-polyvinylpyrridine-wired horse radish peroxidase gel polymer (Os-gel-HRP) to enable the detection of the reduction at 0 mV of hydrogen peroxide (H2O2) derived from a post-column immobilized enzyme reactor (IMER) containing acetylcholinesterase and choline oxidase. In another series of experiments PFCE were initially modified with cast-coated Os-gel-HRP and then treated with glucose oxidase in bovine serum albumin (BSA) and cross-linked with glutaraldehyde to form a bi-layer glucose-Os-gel-HRP PFCE. This bi-layer glucose-Os-gel-HRP PFCE generated a reduction current at 0 mV to H2O2 derived from the reaction of glucose oxidase and glucose in solution. These enzyme-modified PFCE were housed in a radial flow cell and coupled with cation-exchange liquid chromatographic methods to temporally separate substrates in solution for the determination of acetylcholine (ACh) and choline (Ch) in the first experimental series, or glucose in the second experimental series. These two disposable enzyme-modified PFCE exhibited linear current vs. substrate relations, were durable, being usable for approximately 40 determinations, and were sufficiently sensitive to be employed in biological sampling. Both assays utilized the same HPLC equipment. The limit of detection for ACh was 16 fmol/10 microl and that for glucose was 12 micromol/7.5 microl. ACh and Ch were measured from a microdialysate from the frontal cortex of a rat. Glucose in human urine was determined using the bi-layer glucose oxidase-Os-gel-HRP PFCE.
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PMID:Disposable, enzymatically modified printed film carbon electrodes for use in the high-performance liquid chromatographic-electrochemical detection of glucose or hydrogen peroxide from immobilized enzyme reactors. 961 27

Here, we studied the fragmentation of the prothyroid hormone, thyroglobulin (Tg), which occurs during thyroid hormone synthesis, a process which involves iodide, thyroperoxidase, and the H2O2-generating system, consisting of glucose and glucose oxidase. Various peptides were found to be immunoreactive to autoantibodies to Tg from patients and monoclonal antibodies directed against the immunodominant region of Tg. The smallest peptide (40 kDa) bore thyroid hormones and was identified at the C-terminal end of the Tg molecule, which shows homologies with acetylcholinesterase. Similar peptides were obtained by performing metal-mediated oxidation of Tg via a Fenton reaction. It was concluded that the oxidative stress induced during hormone synthesis generates free radicals, which, in turn, cleave Tg into immunoreactive peptides.
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PMID:Production of immunoreactive thyroglobulin C-terminal fragments during thyroid hormone synthesis. 1087 53

The promising advantages of Prussian Blue (PB) as catalyst and of the thick film screen printing technology have been combined to assemble sensors with improved characteristics for the amperometric determination of H(2)O(2). PB-modified screen printed electrodes were applied to detect H(2)O(2) at an applied potential of -0.05 V versus the internal screen printed Ag pseudoreference electrode, showing a detection limit of 10(-7) mol l(-1), a linearity range from 10(-7) to 5x10(-5) mol l(-1), a sensitivity of 234 microA mmol l(-1) cm(-2), and a high selectivity. Improved stability at alkaline pH values was also observed, which made possible their use with enzymes having an optimum basic pH. Then, the immobilisation of a single enzyme (glucose oxidase (GOD) or choline oxidase (ChOX)) or of two enzymes, acetylcholinesterase (AchE) coimmobilised with ChOX, has been performed on the surface of PB modified screen-printed electrodes (SPEs) using glutaraldehyde and Nafion. ChOX has been selected as an example of enzyme working at alkaline pH. The choline biosensors showed a detection limit of 5x10(-7) mol l(-1), a wide linearity range (5x10(-7)-10(-4) mol l(-1)), a high selectivity and a remarkable long term stability of 9 months at 4 degrees C, and at least 4 weeks at room temperature. Similar analytical characteristics and stability were observed with the acetylcholine biosensors.
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PMID:Prussian Blue based screen printed biosensors with improved characteristics of long-term lifetime and pH stability. 1248 62

1. The aim of the present study was to clarify the role of ginsenoside Rh2 as the active compound in Panax ginseng root for lowering plasma glucose in animals. 2. Plasma glucose was assessed using the glucose oxidase method. Changes in the levels of insulin and C-peptide in plasma were measured by ELISA using commercially available kits. 3. After intravenous injection into fasting Wistar rats for 60 min, ginsenoside Rh2 (0.1-1.0 mg/kg) decreased plasma glucose in a dose-dependent manner. In parallel with the decrease in plasma glucose, increases in plasma insulin levels, as well as plasma C-peptide, were observed in rats receiving the same treatment. These effects of Rh2 were reversed by atropine (0.1-1.0 mg/kg), but not affected by the ganglionic nicotinic antagonists pentolinium or hexamethonium (both at 7.5 mg/kg). 4. Disruption of synaptically available acetylcholine (ACh) using an inhibitor of choline uptake (hemicholinium-3; 1-10 microg/kg) or an inhibitor of vesicular ACh transport (vesamicol; 1.5-3.5 mg/kg) abolished the actions of Rh2. In addition, physostigmine (0.1-0.5 mg/kg), at a concentration sufficient to inhibit acetylcholinesterase, enhanced the actions of the ginsenoside Rh2. Thus, mediation of the effects of Rh2 to enhance insulin secretion by ACh released from nerve terminals can be considered. 5. Blockade of the increase in plasma insulin and the plasma glucose-lowering action of Rh2 by 4-diphenylacetoxy-N-methylpiperdine methiodide (4-DAMP; 5-10 microg/kg) indicates the participation of muscarinic M(3) receptors. Increases in plasma C-peptide level induced by Rh2 were also sensitive to 4-DAMP. 6. The results of the present study suggest that ginsenoside Rh2 has the ability to increase insulin secretion as a result of the release of ACh from nerve terminals that then stimulates muscarinic M(3) receptors in pancreatic cells. This finding shows the mechanism for the plasma glucose-lowering action of ginsenoside Rh2, that is one of the major principles contained in P. ginseng root. Thus, ginsenoside Rh2 may be applied as an adjuvant for the management of diabetes.
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PMID:Increase of insulin secretion by ginsenoside Rh2 to lower plasma glucose in Wistar rats. 1644 95

We report a simple and rapid procedure that leads to incorporation of mediator and introduction of amine functionality onto the surface of screen-printed carbon electrodes (SPCE). The electrodes were doped with cobalt phthalocyanine (CoPc) by enhanced adsorption in a process that uses minimal amounts of this redox mediator as compared with CoPc loaded inks. The CoPc-doped SPCE showed a substantially increased sensitivity to hydrogen peroxide and thiocholine as compared to unmodified electrodes. This greatly facilitated their use as transducers for the construction of amperometric biosensors based on enzymes producing oxidizable products such as hydrogen peroxide or thiols. Immobilisation of enzymes including glucose oxidase, acetylcholinesterase and choline oxidase was achieved through their multi-contact electrostatic interaction with polyethyleneimine (PEI) which was electrodeposited on the surface of CoPc-doped electrodes in one step from ethanolic solution. The efficiency of enzyme immobilisation was shown to depend on the molecular weight of the PEI used, reaching a maximum for 25 kDa PEI. The biosensors shown sensitivity to glucose at 130 nA mM(-1) (LOD 0.15 mM) and to acetylcholine at 70 nA mM(-1) (LOD 0.10mM) under +0.6 V. Detection of glucose has been demonstrated at +0.4V with the sensitivity of 60 nA mM(-1) and LOD of 0.33 mM. Possibility of the inhibition analysis of pesticides has been shown for acetylcholinesterase-based sensors.
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PMID:A novel procedure for rapid surface functionalisation and mediator loading of screen-printed carbon electrodes. 1835 65

We report the synthesis of new polymers based on a dimethylacrylamide-methacrylate (DMAA-MA) co-polymer backbone that support both chemical and biological agent decontamination. Polyurethanes containing the redox enzymes glucose oxidase and horseradish peroxidase can convert halide ions into active halogens and exert striking bactericidal activity against gram positive and gram negative bacteria. New materials combining those biopolymers with a family of N-alkyl 4-pyridinium aldoxime (4-PAM) halide-acrylate co-polymers offer both nucleophilic activity for the detoxification of organophosphorus nerve agents and internal sources of halide ions for generation of biocidal activity. Generation of free bromine and iodine was observed in the combined material resulting in bactericidal activity of the enzymatically formed free halogens that caused complete kill of E. coli (>6 log units reduction) within 1 h at 37 degrees C. Detoxification of diisopropylfluorophosphate (DFP) by the polyDMAA MA-4-PAM iodide component was dose-dependent reaching 85% within 30 min. A subset of 4-PAM-halide co-polymers was designed to serve as a controlled release reservoir for N-hydroxyethyl 4-PAM (HE 4-PAM) molecules that reactivate nerve agent-inhibited acetylcholinesterase (AChE). Release rates for HE 4-PAM were consistent with hydrolysis of the HE 4-PAM from the polymer backbone. The HE 4-PAM that was released from the polymer reactivated DFP-inhibited AChE at a similar rate to the oxime antidote 4-PAM.
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PMID:Decontamination of chemical and biological warfare agents with a single multi-functional material. 2019 7

Although the importance of insect saliva in insect-host plant interactions has been acknowledged, there is very limited information on the nature and complexity of the salivary proteome in lepidopteran herbivores. We inspected the labial salivary transcriptome and proteome of Helicoverpa armigera, an important polyphagous pest species. To identify the majority of the salivary proteins we have randomly sequenced 19,389 expressed sequence tags (ESTs) from a normalized cDNA library of salivary glands. In parallel, a non-cytosolic enriched protein fraction was obtained from labial salivary glands and subjected to two-dimensional gel electrophoresis (2-DE) and de novo peptide sequencing. This procedure allowed comparison of peptides and EST sequences and enabled us to identify 65 protein spots from the secreted labial saliva 2DE proteome. The mass spectrometry analysis revealed ecdysone, glucose oxidase, fructosidase, carboxyl/cholinesterase and an uncharacterized protein previously detected in H. armigera midgut proteome. Consistently, their corresponding transcripts are among the most abundant in our cDNA library. We did find redundancy of sequence identification of saliva-secreted proteins suggesting multiple isoforms. As expected, we found several enzymes responsible for digestion and plant offense. In addition, we identified non-digestive proteins such as an arginine kinase and abundant proteins of unknown function. This identification of secreted salivary gland proteins allows a more comprehensive understanding of insect feeding and poses new challenges for the elucidation of protein function.
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PMID:Sialome of a generalist lepidopteran herbivore: identification of transcripts and proteins from Helicoverpa armigera labial salivary glands. 2204 31

This study describes the synthesis of a dual emission probe for the fluorescent ratiometric sensing of hydrogen peroxide (H2O2), enzyme activity, and environmental pH change. Green-emitting fluorescein-5-isothiocyanate (FITC) was conjugated to the amino groups of bovine serum albumin (BSA). This FITC-conjugated BSA acted as a template for the synthesis of red-emitting gold nanoclusters (AuNCs) under alkaline conditions. Under single wavelength excitation, FITC/BSA-stabilized AuNCs (FITC/BSA-AuNCs) emitted fluorescence at 525 and 670nm, which are sensitive to changes in solution pH and H2O2 concentration, respectively. The effective fluorescence quenching of AuNCs by H2O2 enabled FITC/BSA-AuNCs to ratiometrically detect the H2O2 product-related enzyme system and its inhibition, including glucose oxidase-catalyzed oxidation of glucose, acetylcholinesterase/choline oxidase-mediated hydrolysis and oxidation of acetylcholine, and paraoxon-induced inhibition of acetylcholinesterase activity. When pH-insensitive AuNCs were used as an internal standard, FITC/BSA-AuNCs offered a sensitive and reversible ratiometric sensing of a 0.1-pH unit change in the pH range 5.0-8.5. The pH-induced change in FITC fluorescence enabled FITC/BSA-AuNCs to detect an ammonia product-related enzyme system. This was exemplified with the determination of urea in plasma by urease-mediated hydrolysis of urea.
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PMID:Fluorescein-5-isothiocyanate-conjugated protein-directed synthesis of gold nanoclusters for fluorescent ratiometric sensing of an enzyme-substrate system. 2570 28


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