Choline-esterases, inhibition

Choline, 413, 773 Choline-esterase, 262 Choline-esterases, inhibition by... 

Choudhary MI, Yousuf S, Nawaz SA, Ahmed S, Atta-ur-Rahman (2004) Cholin- esterase inhibiting withanolides from Withania somnifera. Chem Pharm Bull 52(11) 1358-1381 Kirson I, Glotter E (1981) Recent developments in naturally occurring ergostane type steroids a review. J Nat Prod 44 633-647... 

Spray with butter yellow then expose to UV Malathion exposure to bromine vapour Yellow spots produced on spraying with palladium(ll) chloride Enzymic choline esterase inhibition method or tetra-bromomethane in acetone or citric acid in acetone Fluorescent spots with palladium(ll)-calcein or palladium -calcein blue complex... 

Johnson has described a method for the estimation of physostigmine in the salicylate for the determination of minute amounts of the alkaloid Ellis, Plaehte and Straus have devised processes depending on (a) inhibition of serum choline-esterase by the alkaloid, or (b) measurement of the colour intensity produced by the conversion of physostigmine to rubreserine in an alkaline medium. i ... 

Ellis, Krayer and Plachte have shown that the degradation products of physostigmine, eseroline and eserine-brown do not inhibit choline-esterase, but rubreserine and eserine-blue are inhibitors in vitro, having... 

Ph. C CH. C(CH,. N(Br)Mc3) C(0. CO. NMca). CH CH, an analogue of prostigmine, shows marked inhibition for i/i-choline-esterase, but is only slightly active towards true choline-esterase. 

DFP inhibits serum proteinase group of enzymes, including choline esterase. Ninhydrin deaminates amino acids and forms a blue complex with the NH3 released. 

Thus (+)-[Ni(phen)3]2+ and (+)-[Ru(phen)3]2+ are more toxic to mice by intraperitoneal injection (153) than are their enantiomers. As the mice exhibited symptoms of curare poisoning (24) which is thought to be due to inhibition of acetyl choline-esterase, the effects of some other complexes on this enzyme were studied. (—)-[Ru(bipy)3]2+ inhibits (153) this enzyme much more than does (- -)-[Ru(bipy)3]2+. However, the enantiomers of [Ru(bipy)3]2+ have equal toxicities to mice (153), and (+)-[Ru(phen)3]2+ is more readily absorbed from the intraperitoneal cavity than is (—)-[Ru(phen)3]2+.The configurations of (—)-[Ru(bipy)3]2+ and (+)-[Ru(phen)3]2+ have been said (44) to be identical on the basis of the physiological work outlined above, but this conclusion, resting as it does on physiological results which are of doubtful relationship to one another is very tenuous, and conflicts with other work (see p. 78). 

Barratt, J.O., Thrombin and calcium chloride in relation to coagulation, Biochem. J. 9, 511-543, 1915 Van der Meer, C., Effect of calcium chloride on choline esterase. Nature 171, 78-79, 1952 Bhat, R. and Ahluwalia, J.C., Effect of calcium chloride on the conformation of proteins. Thermodynamic studies of some model compounds, Int. J. Pept. Protein Res. 30,145-152,1987 Furihata, C., Sudo, K., and Matsushima, T, Calcium chloride inhibits stimulation of replicative DNA... 

Enzymatic based devices have been widely reported for the detection of organic pollutants (see Table 3.2.4). The selective inhibition of choline esterases, principally acetylcholine esterase (AchE) (Guibault and Das, 1970), and butylcholine esterase (BchE) (Skladal, 1992), have been used for the detection of organophosphorous, and carbamate insecticides. However, there are some limitations. 

During the following years, the picture became confused since acetylcholine-hydrolyzing enzymes obtained from various organs were found to have optimal activity at different concentrations of substrate. An explanation for this was put forward by Alles and Hawes (A13). They demonstrated the existence of two choline-esterases The first, whose activity was greatest at low concentrations and was inhibited by excess... 

The procedures described above are most useful to diagnose esterase inhibition in individual subjects. For reasons which are not clear, however, there are substantial person-to-person variations in response to cholin-... 

Specific choline esterase develops its max activity at pH 7 and at low levels OF acetylcholine (less than 2.5 mg %). Both enzymes are inhibited by very small quantities of physostig-mine (eserine). Acetylcholinesterase is inhibited by phosphorus-containing insecticides and nerve gases. 

Acetylcholinesterase, the enzyme that hydrolyzes acetylcholine to choline in the postsynaptic membrane, is a serine esterase inhibited by diisopropyl fluorophosphate, sarin, physostigmine, and parathion (Table 11.4). These substances are extremely toxic and cause paralysis. Other toxins block the acetylcholine receptor (antagonists) or lock it open (agonists). Nicotine is an agonist. 

Ehrich. M.. Corrcii, L., and Verone,si, B. (1997). Acetyl-choline.stcrasc and neuropathy target esterase inhibitions in neuroblastoma ccll.s to distinguish organopbosphorus compounds causing acute and delayed neurotoxicity. Fundam. Appl. Toxicol. 38,. 55-63. 

Enzyme inhibition sensors are the most commonly reported enzyme-based biosensors for the detection of toxic compounds and heavy metal ions. The sensors are based on the selective inhibition of specific enzymes by classes of compounds or by the more general inhibition of enzyme activity. Most of the research carried out has been directed toward the detection of organophosphorus and carbamate insecticides and the triazine herbicides and metal ions analysis [72,73]. Several enzymes have been used in inhibition sensors for pesticides and heavy metal analysis using water, soil, and food samples including choline esterase, horseradish peroxidase, polyphenol oxidase, urease, and aldehyde dehydrogenase. 

If an inhibitor is present in air or water then the activity of choline esterase decreases and the degree of activity loss is related to the concentration of the inhibitor (e.g., pesticides). If the inhibition is reversible then the inhibitor is washed out, if it is irreversible then the pad with the immobilized enzyme must be exchanged. An improved system was later commercialized by Midwest Research, Kansas City, Missouri, USA [253]. 

Aceclidine exerts an inhibiting action on pseudo- and acetyl-choline-esterase but is 1,000-10,000 times less active than neostigmine methylsulphate. 

XXXIX Pirimiphos methyl I, A Inhibits choline esterase 1414 (R), 1180 (M)... 

De ALMEIDA R.M., POSPISIL F., VACKOVA K. and KUTACEK M. 1980. Effect of humic acids on the inhibition of pea choline esterase and choline a-cyltransferase with malathion. Biologia Plantarum, 22 167-175. 

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