Use of ethopropazine and BW 284C51 as selective inhibitors for cholinesterases from various species

Mikalsen, Arne; Andersen, Reidar; Alexander, Jan

doi:10.1016/0742-8413(86)90152-0

Cited by 20 publications

(22 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…To demonstrate the presence of two ChE activities in O. latipes, extracts from adult medaka were incubated with the inhibitors physostigmine, which inhibits all ChEs; BW284c51, which inhibits AChE selectively; and ethopropazine, which inhibits BChE preferentially, and assayed for activity with ATCh and PTCh [16], [52], [53]. Different dose-response curves were observed with the two substrates for each inhibitor, suggesting the presence of at least two ChE activities (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…This explanation, as well as the others offered on the molecular basis of substrate and inhibitor specificity could be tested by site-directed mutagenesis. In any event, it should be kept in mind that vertebrate ChEs cannot always be characterized as AChE or BChE simply on the basis of diagnostic inhibitor specificities [53], and that molecular analysis can provide additional valuable information about the nature of ChE activity. Since molecular data are not available for the atypical BChEs from T. marmorata , P. flesus, P. platessa, and A. dussumieri , we cannot compare at the molecular level the atypical BChE from O. latipes with these enzymes.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Evolution of Acetylcholinesterase and Butyrylcholinesterase in the Vertebrates: An Atypical Butyrylcholinesterase from the Medaka Oryzias latipes

Pezzementi

Nachon²,

Chatonnet

2011

PLoS ONE

View full text Add to dashboard Cite

Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) are thought to be the result of a gene duplication event early in vertebrate evolution. To learn more about the evolution of these enzymes, we expressed in vitro, characterized, and modeled a recombinant cholinesterase (ChE) from a teleost, the medaka Oryzias latipes. In addition to AChE, O. latipes has a ChE that is different from either vertebrate AChE or BChE, which we are classifying as an atypical BChE, and which may resemble a transitional form between the two. Of the fourteen aromatic amino acids in the catalytic gorge of vertebrate AChE, ten are conserved in the atypical BChE of O. latipes; by contrast, only eight are conserved in vertebrate BChE. Notably, the atypical BChE has one phenylalanine in its acyl pocket, while AChE has two and BChE none. These substitutions could account for the intermediate nature of this atypical BChE. Molecular modeling supports this proposal. The atypical BChE hydrolyzes acetylthiocholine (ATCh) and propionylthiocholine (PTCh) preferentially but butyrylthiocholine (BTCh) to a considerable extent, which is different from the substrate specificity of AChE or BChE. The enzyme shows substrate inhibition with the two smaller substrates but not with the larger substrate BTCh. In comparison, AChE exhibits substrate inhibition, while BChE does not, but may instead show substrate activation. The atypical BChE from O. latipes also shows a mixed pattern of inhibition. It is effectively inhibited by physostigmine, typical of all ChEs. However, although the atypical BChE is efficiently inhibited by the BChE-specific inhibitor ethopropazine, it is not by another BChE inhibitor, iso-OMPA, nor by the AChE-specific inhibitor BW284c51. The atypical BChE is found as a glycophosphatidylinositol-anchored (GPI-anchored) amphiphilic dimer (G2 a), which is unusual for any BChE. We classify the enzyme as an atypical BChE and discuss its implications for the evolution of AChE and BChE and for ecotoxicology.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Evolution of Acetylcholinesterase and Butyrylcholinesterase in the Vertebrates: An Atypical Butyrylcholinesterase from the Medaka Oryzias latipes

Pezzementi

Nachon²,

Chatonnet

2011

PLoS ONE

View full text Add to dashboard Cite

show abstract

“…For example, different concentrations of Nu‐1250 (a prostigmine analogue, m ‐hydroxyphenyltrimethylammonium bromide) were required to inhibit 100% of AChE and BChE activities in tissue extracts or plasma from various animals – horse AChE (1 µ m ), dog AChE (10 µ m ), human AChE (10 µ m ), dog BChE (200 µ m ), horse BChE (10 µ m ) and Hu BChE (1 m m ) (Hawkins and Mendel, ). Inter‐species differences in sensitivity to Iso‐OMPA and ethopropazine were also reported by other investigators (Austin and Berry, ; Mikalsen et al ., ). By titrating BChE activities in the blood of common laboratory animals against ethopropazine, we determined that ethopropazine, at 20 µ m , inhibited > 98% BChE activity in whole blood of all the animal species tested.…”

Section: Discussionmentioning

confidence: 93%

“…Results confirmed previous observations on the selectivity of ethopropazine for BChE, and showed that 20 µ m ethopropazine and 500 n m (−)‐huperzine A can be successfully used to measure AChE and BChE activities simultaneously in a mixture of human AChE and human BChE. However, different ChEs are known to vary in their selectivity for inhibitors (Austin and Berry, ; Hawkins and Mendel, ; Mikalsen et al ., ). For example, different concentrations of Nu‐1250 (a prostigmine analogue, m ‐hydroxyphenyltrimethylammonium bromide) were required to inhibit 100% of AChE and BChE activities in tissue extracts or plasma from various animals – horse AChE (1 µ m ), dog AChE (10 µ m ), human AChE (10 µ m ), dog BChE (200 µ m ), horse BChE (10 µ m ) and Hu BChE (1 m m ) (Hawkins and Mendel, ).…”

Section: Discussionmentioning

confidence: 99%

“…In this study, AChE activity in human whole blood was measured in the presence of 100 µ m ethopropazine using propionylthiocholine (PTC) as the substrate. Subsequently, a study that tested the inhibitory activity of ethopropazine towards commonly used ChE preparations showed that 50 µ m ethopropazine completely inhibited horse serum BChE without affecting bovine erythrocyte AChE (Mikalsen et al ., ). In rats, 5 µ m ethopropazine completely inhibited BChE activity in plasma and the cortex, but did not affect AChE activity in the cortex.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Development and validation of a simple assay for the determination of cholinesterase activity in whole blood of laboratory animals

Naik

Liu

Saxena

2012

J of Applied Toxicology

View full text Add to dashboard Cite

Current methods for measuring acetylcholinesterase (AChE) activities in whole blood use butyrylcholinesterase (BChE)‐selective inhibitors. However, the poor selectivity of these inhibitors results in the inhibition of AChE activity to some degree, leading to errors in reported values. The goal of this study was to develop and validate a simple assay for measuring AChE and BChE activities in whole blood from humans as well as experimental animals. Blood was fractionated into plasma and erythrocytes, and cholinesterase activities were titrated against ethopropazine and (−)‐huperzine A to determine the lowest concentration of ethopropazine that inhibited BChE completely without affecting AChE activity and the lowest concentration of (−)‐huperzine A that inhibited AChE completely without interfering with BChE activity. Results indicate that 20 µm ethopropazine can be successfully used for the accurate measurement of AChE activity in blood from humans as well as animals. Use of (−)‐huperzine A is not required for measuring BChE activity in normal or ‘exposed’ blood samples. The method was validated for blood from several animal species, including mice, rats, guinea pigs, dogs, minipigs, and African green, cynomolgus and rhesus monkeys. This method is superior to all reported methods, does not require the separation of erythrocyte and plasma fractions, and is suitable for measuring cholinesterase activities in fresh or frozen blood from animals that were exposed to nerve agents or those that were administered high doses of BChE. The method is simple, direct, reproducible, and reliable and can easily be adapted for high‐throughput screening of blood samples. Published 2012. This article is a US Government work and is in the public domain in the USA.

show abstract

Acetylcholinesterase in the human erythron. I. Cytochemistry

Koekebakker

Barr

1988

American J Hematol

View full text Add to dashboard Cite

The successful demonstration and localisation of acetylcholinesterase (AChE), in cells by a cytochemical technique requires maximal expression of enzyme activity, minimal loss of AChE and precise, quantitative generation of reaction product at the actual site of the protein in vivo. These requirements are addressed in a standard technique that has been modified to avoid or optimise fixation and to exhibit enzyme activity under close-to-physiological conditions of osmolality, pH, and temperature. With these refinements and with the use of a variety of substrates and enzyme inhibitors of different specificities, true AChE was demonstrable on the membrane of erythrocytes and in the nucleus and cytoplasm of erythroblasts in bone marrow and of the constituent cells of erythroid clones in vitro. The activity in erythrocytes from umbilical cord blood was less than that in corresponding cells from the peripheral circulation of adults. AChE was observed also in human megakaryocytes and in leucocytes at all levels of differentiation, including the components of granulocyte-macrophage clones. Pseudocholinesterase was detected likewise across the spectrum of erythroid (and leucocyte) ontogeny, suggesting that these enzymes may exercise an important function in hematopoiesis.

show abstract

Use of ethopropazine and BW 284C51 as selective inhibitors for cholinesterases from various species

Cited by 20 publications

References 2 publications

Evolution of Acetylcholinesterase and Butyrylcholinesterase in the Vertebrates: An Atypical Butyrylcholinesterase from the Medaka Oryzias latipes

Evolution of Acetylcholinesterase and Butyrylcholinesterase in the Vertebrates: An Atypical Butyrylcholinesterase from the Medaka Oryzias latipes

Development and validation of a simple assay for the determination of cholinesterase activity in whole blood of laboratory animals

Acetylcholinesterase in the human erythron. I. Cytochemistry

Contact Info

Product

Resources

About