Acetyl cholinesterase activity

Acetyl cholinesterase activity AChE,. brain Neurotoxic parameter Organophosphate and carbamate pesticides Brain tissue 13-15... 

Acetyl cholinesterase activity AChE Ellman et al. (1961) Sturm et al. (1999)... 

Acetyl cholinesterase activity AChE, lab 6 muscle Bocquene et al. (1990)... 

Csillik B, Joo F, Kasa P, Tomity I, Kalman GY (1964) Development of acetyl-cholinesterase-active structures in the rat archicerebellar cortex. Acta Biol. Acad Scl Hung., 15, 11-17. 

Organophosphate and carbamate pesticides are potent inhibitors of the enzyme cholinesterase. The inhibition of cholinesterase activity by the pesticide leads to the formation of stable covalent intermediates such as phosphoryl-enzyme complexes, which makes the hydrolysis of the substrate very slow. Both organophosphorus and carbamate pesticides can react with AChE in the same manner because the acetylation of the serine residue at the catalytic center is analogous to phosphorylation and carbamylation. Carbamated enzyme can restore its catalytic activity more rapidly than phosphorylated enzyme [17,42], Kok and Hasirci [43] reported that the total anti-cholinesterase activity of binary pesticide mixtures was lower than the sum of the individual inhibition values. 

Carboxylesterase from the liver, butyryl cholinesterase and acetyl cholinesterase from erythrocytes do not interfere with analysis, i.e. they do not exercise any activity in respect of the substrate. Contamination of the sample by glycerol, soap and hand cream must be avoided. 

For determination of how these inhibitors interact with housefly acetyl cholinesterase the method of Aldridge and Davidson(3) was employed. The log % residual activity is plotted against (molar concentration)(incubation time). When straight line results, it is interpreted that the enzyme-inhibitor interaction is governed by pseudo first order kinetics and is a bimolecular reaction. For the... 

Ibrahim et al. [182] isolated four sesquiterpene lactones from the ethyl acetate soluble fraction of Amberboa ramosa. One compound, Amberbin C, was found to be new while other three compounds, Amberin, Amberbin A, and Amberbin B, were previously reported. All compounds showed inhibitory activities against acetyl cholinesterase and butyryl cholinesterase. 

A dramatic increase in the brain delivery of 2-PAM by the use of Pro-2-PAM is thus achieved, resulting in a re-activation of phosphorylated brain acetyl-cholinesterase in vivo ... 

Kolf-Clauw M, Jez S, Ponsart C, Delamanche IS. Acetyl- and pseudo-cholinesterase activities of plasma, erythrocytes, and whole blood in male beagle dogs using Elhnan s assay. Vet Hum Toxicol 2000 42 216-9. 

Surfactants. Several anionic surfactants, at low concentrations, strongly inhibit horse serum cholinesterase, whereas nonionic surfactants are without effect with acetyl- or propionylthiocholine as substrate (T8). Low concentrations of the hemolysin, alkylphenoxy polyethoxyethanol (Triton X-100) strongly inhibit human plasma cholinesterase activity with acetylcholine as substrate (S37). 

With an excessive, single exposure, the result will be either a systemic pesticide poisoning or a topical lesion frequently observed on the skin or in the eyes. Since most acute intoxications are from the carbamate and organoposphate insecticides, the systemic manifestations are cholinergic and are due to the inhibition of acetyl cholinesterase and the resultant accumulation of the neurotransmitter acetylcholine, at the synapse. Topical effects, in contrast, either are the result of the irritant properties of the chemicals in the formulation or have an allergenic basis for their occurrence (3). However, topical effects are not necessarily exclusively the result of exposure to the active ingredient in the formulation but may result from a reaction to one or more inerts as well. 

The reactions show some typical oxidations of insecticides catalyzed by CYP enzymes. Carbofuran is hydroxylated to another active compound carbaryl is demethylated or hydroxylated and aldrin is epoxidated to diel-drin, which also has insecticidal properties. Phosphorothionates must be oxidized to the phosphates by CYP enzymes in order to become inhibitors of acetyl cholinesterase. Parathion-methyl is transformed to the oxon analogue, paraoxon-methyl, which is the toxic compound. It also can be demethylated to the inactive desmethyl-parathion-methyl. 

The effect of a number of oximes derived from pyridines on rat-brain acetyl cholinesterase which had been inactivated by isopropyl methyl-phosphonofluoridate has been studied, the most effective at restoring enzymic activity being (75). Acetyl cholinesterase is also inhibited by aryl... 

The cell bodies of neurons that involve NE are located in the brain stem, with projections to the thalamus, cortex,hippocampus, and cerebellum. Other neurotransmitters, such as ACh and some neuropeptides, are broken down while still in the synaptic cleft. In the synapses connecting neurons and muscle cells, the enzyme acetyl cholinesterase performs this task. Excitatory ACh receptors that activate skeletal musdes at the neuromuscular juncture are called nicotinic receptors because they are stimulated by nicotine. 

Anticholinesterase activity Acetyl cholinesterase/choline oxidase... 

Racchi, M., MazzucchelU, M., Porrello, E., Lanni, C., Govoni, S. Acetyl cholinesterase inhibitors novel activities of old molecules. Pharma. Res. 2004, 50, 441 51. 

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