Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.1.8 (cholinesterase)
 12,691 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A new enzymatic method for the determination of serum pseudo-cholinesterase activity is described. Choline, which is liberated from benzoylcholine as substrate by cholinesterase, is oxidized by choline oxidase to betaine with the simultaneous production of hydrogen peroxide, which oxidatively couples with 4-aminoantipyrine and phenol in the presence of peroxidase to yield a chromogen with maximal absorbance at 500 nm. The calibration curve is linear up to 1500 units per liter of serum. The method is reproducible, and the results correlate well with those obtained by the method using butyrylthiocholine as substrate and 5,5'-dithiobis-(2-nitrobenzoic acid) as color reagent.
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PMID:New enzymatic assay of cholinesterase activity. 2 Feb 53

The effects of ionic strength, urea, calcium and fluorine ions, ouabain and cholinesterase inhibitors on the changes in the ionization equilibrium of an erythrocyte suspension under heating were studied. Proton release by erythrocytes was compared to a release of potassium ions and hemoglobin from the cells. The proton release under heating is mainly determined by the physico--chemical properties of superficial structures of erythrocytes and does not depend on the activity of cholinesterase, ATPase and glycolytic processes.
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PMID:[Changes in the ionization equilibrium of erythrocyte suspension under heating]. 13 48

An electrochemical method was elaborated for the continuous determination of enzymatic hydrolysis of acetylcholine. In the electrochemical system applied the aqueous solution of the enzyme is separated from the aqueous solutions of substrates by a semipermeable membrane. In this way cholinesterase is used many times for reactions. Changes in the concentration of hydrogen ions were determined with molybdenum electrodes, one of which was used as an indicator and immersed in enzyme solution and the other served for comparison and was immersed in the solution of acetylcholine flowing to the measuring system.
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PMID:Electrochemical method for continuous determination of enzymatic acetylocholine hydrolysis. 59 97

At the same temperature and with adequate circulation of blood or receptor solution beneath it the permeability of the stratum corneum of the rabbit ear to T2O or to 32P-TPP was the same in vivo as in vitro. When skin permeability was measured in vitro, the subcutaneous adipose tissue present in the full-thickness skin of the rat delayed the penetration of CR, a lipophilic substance with a low water solubility, and decreased the permeability constant by nearly 3x. The retardant solvent PEG 300 did not penetrate the stratum corneum; it formed a hydrogen-bonded complex with the cholinesterase inhibitor VX, thereby reducing the thermodynamic activity and penetration rate of this compound through the stratum corneum. The accelerant solvent DMSO removed protein components from the stratum corneum; electron microscope studies showed that the cells of stratum corneum so treated became separated from one another, and their contents became stainable in bulk with Pb++, indicating the creation of new diffusion pathways. When the temperature, clearance of penetrant from the lower surface of the stratum corneum and penetrant formulation were the same in vivo as in vitro, and the surface of the stratum corneum was saturated with the penetrant or its solution, the results of permeability measurements made in vivo were similar to those made in vitro.
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PMID:Factors affecting the permeability of skin. The relation between in vivo and in vitro observations. 75 61

Aminoalkyl benzenesulfonyl fluorides, like organophosphates, act as irreversible inhibitors of serine proteinases by splitting off hydrogen fluoride to form an enzyme-inhibitor complex, stable in the physiological pH region. Several of these compounds are characterized by a higher rate of inhibition when trypsin is used and the second order rate constants are compared with those of organophosphates. On the other hand, upon inhibition of human serum cholinesterase by DFP and 4-nitrophenyl diethyl phosphate, some orders of magnitude higher than that of benzenesul fonyl fluorydes are observed. As shown by an oral toxicity study in mice similar differences exist with respect to LD50 values.
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PMID:[Inhibition of the activity of human serum cholinesterase by aminoalkyl benzenesulfonyl fluorides]. 102 6

The synthesis of styrylpyridine methiodides where a hydrogen of the pyridyl moiety was replaced by the hydroxyiminomethyl group produced highly effective inhibitors of acetylcholinesterase. As starting materials 4-methylpyridine-2-aldoxime and 2-methylpyridine-4-aldoxime methiodides were prepared which, together with 4-imidazolylethenyl-pyridine-2-aldoxime methiodide, were the only substances for which some activity as reactivators of phosphorylated electric eel cholinesterase in vitro could also be found.
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PMID:Structure-activity relationships in reactivators of organophosphorus-inhibited acetylcholinesterase. 10. Hydroxyiminomethylarylethenylpyridine methiodides. 117 61

A suitable enzyme sensor for the analysis of anticholinesterase compounds of pharmaceutical interest is described. It is based on the competitive inhibiting properties of these compounds on the enzyme butyrylcholinesterase and it is constituted by a hydrogen peroxide amperometric electrode modified by a superimposed Nylon membrane containing two chemically immobilized biological mediators (butyrylcholinesterase and choline oxidase). Some applications to the analysis of several pharmaceutical forms containing different compounds showing anticholinesterase activity are also reported and evaluated.
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PMID:Determination of compounds with anticholinesterase activity in commercial drugs by a new enzyme sensor. 129 77

An analytical method was developed with sensitivity to detect clinically significant concentrations of heptylphysostigmine (HP), a new physostigmine derivative with potent and long-lasting inhibitory activity on cholinesterase. HP, an experimental drug for Alzheimer disease, was measured in human plasma by high-performance liquid chromatography with electrochemical detection with use of a normal-phase column and acetonitrile buffer containing tetrahydrofuran and sodium acetate, pH 4.6. The limit of detection of the method was 0.125 ng/ml using a 2-ml sample of plasma. Analytical recovery of HP was 53.04 +/- 7.75% for plasma in the range 0.25-2.5 ng/ml. Stability studies conducted at 37 degrees C indicated that the drug was stable in 1 M hydrochloric acid, 1 M hydrogen peroxide and sodium acetate-buffered solution at pH 4 for at least 6 h but at pH 7 it degraded slightly to 79% at 6 h and was unstable in 1 M sodium hydroxide with only 9% of the parent compound remaining at 30 s. HP was stable when exposed to ultraviolet light at 22 degrees C or 100% relative humidity at 37 degrees C, with almost 80 and 75% of the parent compound remaining after 4 and 28 days, respectively. HP was stable in plasma at 4 degrees C for 0.25 h, and it slowly degraded to 56 and 28% of the original concentration by 1 and 2 h, respectively. HP was highly unstable in plasma at higher temperatures; at 22 and 37 degrees C it degraded immediately to 48 and 36% of the original concentration and was not detected after 0.5 and 0.25 h, respectively.
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PMID:Determination of heptylphysostigmine in plasma by high-performance liquid chromatography with electrochemical detection. 160 60

A simple method for the separate determination of acetylcholinesterase and butyrylcholinesterase activities in amniotic fluid is reported. This determination is performed with an enzyme electrode involving an immobilized choline oxidase membrane associated with the amperometric detection of hydrogen peroxide. Acetylcholine or butyrylcholine, in the presence of samples containing acetylcholinesterase or butyrylcholinesterase are specifically hydrolyzed, the formation of choline being detected vs time by the sensor with no need for a selective inhibitor. The dynamic linear ranges for acetylcholinesterase and butyrylcholinesterase are respectively 100 microU to 10 mU and 30 microU to 3 mU per ml sample.
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PMID:Rapid and sensitive discriminating determination of acetylcholinesterase activity in amniotic fluid with a choline sensor. 177 89

Serum cholinesterase activity and the dibucaine numbers have been determined by using a hydrogen peroxide electrode and the enzyme choline oxidase immobilized on a nylon net. The analysis procedure is extremely simple and very fast allowing 30 cholinesterase determinations per hour. Both cholinesterase activity and dibucaine number measurements could be performed in 5 min and by using serum samples of only 10 microliters. When used in sera the probe showed no interference from electroactive compounds present in blood, and also showed good stability and reproducibility. These features make this sensor appropriate for continuous extracorporeal circuit blood monitoring of succinylcholine during surgery.
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PMID:Determination of serum cholinesterase activity and dibucaine numbers by an amperometric choline sensor. 217 37


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