A mercaptocholine used as a reagent for the determination of CHOLINESTERASES. It also serves as a highly selective nerve stain.
An agent used as a substrate in assays for cholinesterases, especially to discriminate among enzyme types.
An aspect of cholinesterase (EC 3.1.1.8).
Cholinesterases are a group of enzymes that catalyze the hydrolysis of acetylcholine and other choline esters, playing crucial roles in the termination of impulse transmission at cholinergic synapses and neuro-muscular junctions, and in the metabolism of certain drugs and toxic substances.
An enzyme that catalyzes the hydrolysis of ACETYLCHOLINE to CHOLINE and acetate. In the CNS, this enzyme plays a role in the function of peripheral neuromuscular junctions. EC 3.1.1.7.
Drugs that inhibit cholinesterases. The neurotransmitter ACETYLCHOLINE is rapidly hydrolyzed, and thereby inactivated, by cholinesterases. When cholinesterases are inhibited, the action of endogenously released acetylcholine at cholinergic synapses is potentiated. Cholinesterase inhibitors are widely used clinically for their potentiation of cholinergic inputs to the gastrointestinal tract and urinary bladder, the eye, and skeletal muscles; they are also used for their effects on the heart and the central nervous system.

New thiocholine ester substrates for the assay of human serum cholinesterase. (1/22)

BACKGROUND: Several thiocholine alkanoyl esters were newly synthesized and explored as substrates for the assay of human serum cholinesterase after being subjected to the Ellman reaction (Arch Biochem Biophys 1958;74:443-50 and Arch Biochem Biophys 1959;82:70-7). METHODS: We synthesized thiocholine ester iodides by the method of Renshow et al. (J Am Chem Soc 1938;60:1765-70). We examined solubility in H(2)O, substrate specificity serum for cholinesterase, (spontaneous) self-hydrolysis, storage stability, and reaction conditions for measurement of the activity of the enzyme. RESULTS: Isobutyryl and cyclohexane-carboxyl esters showed the best efficiency for the specific and stable assay of human serum cholinesterase. Aqueous solubility of each was >10 mmol/L, and the reactivity with acetylcholinesterase was negligible. For isobutyryl and cyclohexane-carboxyl esters, respectively, spontaneous hydrolysis in the aqueous phase was approximately 1/25 and approximately 1/175 slower than the enzymatic hydrolysis, and assays with these substrates were linear to 1800 and 3000 U/L, respectively. The K(m) values of these acylthiocholines with human cholinesterase were almost equivalent (6.9 x 10(-3) mmol/L). The substrates were stable in aqueous solution and in the solid state as the iodides for at least 5 years at 5 degrees C. CONCLUSIONS: The isobutyrate and cyclohexane-carboxylate of thiocholine are suitable for the specific assay of human serum cholinesterase.  (+info)

Effects of salinity on aldicarb toxicity in juvenile rainbow trout (Oncorhynchus mykiss) and striped bass (Morone saxatilis x chrysops). (2/22)

Fluctuations in several environmental variables, such as salinity, can influence the interactions between organisms and pollutants in aquatic organisms, and, therefore, affect the toxicity of xenobiotics. In this study, after 2 species of fish, rainbow trout (Oncorhynchus mykiss) and hybrid striped bass (Morone saxatilis x chrysops) were acclimated to 4 salinity regimens of 1.5, 7, 14, and 21 ppt for 1 week and then exposed to 0.5 mg/l aldicarb. Mortality, brain, and muscle cholinesterase levels were measured after 96 h. Rates of (14)C-aldicarb sulfoxide formation were determined in kidney (trout only), liver, and gill microsomes from each species acclimated to the 4 salinity regimens. Salinity significantly enhanced aldicarb toxicity, cholinesterase inhibition, and (14)C-aldicarb sulfoxide formation in rainbow trout but not in striped bass. In vitro incubations with (14)C-aldicarb and the cytochrome P450 (CYP) inhibitor, N-benzylimidazole, did not significantly alter aldicarb sulfoxide formation in tissue microsomes from either species of fish, indicating CYP did not contribute to aldicarb sulfoxidation. Salinity increased flavin-containing monooxygenase (FMO) mRNA expression and catalytic activities in microsomes of liver, gill, and kidney of rainbow trout, which was consistent with the salinity-induced enhancement of aldicarb toxicity. Salinity did not alter FMO mRNA expression and catalytic activities in striped bass, which was also consistent with the lack of an effect of salinity on aldicarb toxicity in this species. These results suggest that salinity-mediated enhancement of aldicarb toxicity is species-dependent, and at least partially due to the salinity-related upregulation of FMOs, which, in turn, increases the bioactivation of aldicarb to aldicarb sulfoxide, which is a more potent inhibitor of cholinesterase than aldicarb.  (+info)

Potentiation effect of choline esters on choline-catalysed decarbamoylation of dimethylcarbamoyl-acetylcholinesterase. (3/22)

The choline esters potentiated the choline-catalysed decarbamoylation of dimethylcarbamoyl-acetylcholinesterase in proportion to the length of acyl group, although esters containing an acyl chain longer than the hexanoyl group exhibited a corresponding decrease in the potentiation. In structural requirement analysis it was found that both the quaternary ammonium moiety and the ester bond were important for the effective acceleration of choline-catalysed decarbamoylation. In general, the respective thiocholine ester was found to be more effective than the corresponding choline ester. Whereas the binding affinity (Ka) of choline in the decarbamoylation was not significantly altered, the maximum decarbamoylation rate (kr(max.)) of choline was greatly enhanced in the presence of choline esters or thiocholine esters. Along with the above observation, the isotope solvent effect, the effect of ionic strength and the antagonism studies demonstrate that the choline esters or thiocholine esters may interact with one of peripheral anionic sites, and thereby make the choline-catalysed decarbamoylation more favourable.  (+info)

Hydrolysis of oxo- and thio-esters by human butyrylcholinesterase. (4/22)

Catalytic parameters of human butyrylcholinesterase (BuChE) for hydrolysis of homologous pairs of oxo-esters and thio-esters were compared. Substrates were positively charged (benzoylcholine versus benzoylthiocholine) and neutral (phenylacetate versus phenylthioacetate). In addition to wild-type BuChE, enzymes containing mutations were used. Single mutants at positions: G117, a key residue in the oxyanion hole, and D70, the main component of the peripheral anionic site were tested. Double mutants containing G117H and mutations on residues of the oxyanion hole (G115, A199), or the pi-cation binding site (W82), or residue E197 that is involved in stabilization of tetrahedral intermediates were also studied. A mathematical analysis was used to compare data for BuChE-catalyzed hydrolysis of various pairs of oxo-esters and thio-esters and to determine the rate-limiting step of catalysis for each substrate. The interest and limitation of this method is discussed. Molecular docking was used to analyze how the mutations could have altered the binding of the oxo-ester or the thio-ester. Results indicate that substitution of the ethereal oxygen for sulfur in substrates may alter the adjustment of substrate in the active site and stabilization of the transition-state for acylation. This affects the k2/k3 ratio and, in turn, controls the rate-limiting step of the hydrolytic reaction. Stabilization of the transition state is modulated both by the alcohol and acyl moieties of substrate. Interaction of these groups with the ethereal hetero-atom can have a neutral, an additive or an antagonistic effect on transition state stabilization, depending on their molecular structure, size and enantiomeric configuration.  (+info)

Nerve agent analogues that produce authentic soman, sarin, tabun, and cyclohexyl methylphosphonate-modified human butyrylcholinesterase. (5/22)

 (+info)

Facile identification and quantitation of protein phosphorylation via beta-elimination and Michael addition with natural abundance and stable isotope labeled thiocholine. (6/22)

 (+info)

Direct detection of the hydrolysis of nerve agent model compounds using a fluorescent probe. (7/22)

 (+info)

Piperidine-4-methanthiol ester derivatives for a selective acetylcholinesterase assay. (8/22)

The activity of acetylcholinesterase (AChE) is measured to obtain pathological information about the cholinergic system in various disease states and to assess the effect of AChE inhibitors. Using Ellman's method that is commonly used in such examinations, butyrylcholinesterase inhibitors must be added to measure AChE-specific activity because of low selectivity of AChE toward traditional substrates; however, such inhibitors also inhibit AChE. Therefore, it is desirable to obtain an AChE selective substrate that can be used with the Ellman's method. Here, we synthesized novel AChE substrates, 1-methyl-4-acetylthiomethylpiperidine and 1,1-dimethyl-4-acetylthiomethylpiperidine, and evaluated the hydrolysis rate and AChE selectivity by comparison with the results obtained when traditional substrates were used. The hydrolysis rate of the novel compounds by human AChE was one order of magnitude lower than that of the traditional substrates, acetylthiocholine and acetyl-beta-methylthiocholine, whereas the hydrolysis rate using human butyrylcholinesterase was two orders of magnitude lower than that of the traditional substrates. This indicated that AChE showed selectivity towards the novel substrates which was one order of magnitude higher than that of the traditional substrates. The hydrolysis of the novel compounds in a rat cerebral cortical homogenate and a monkey whole blood was completely inhibited by 1 muM of the specific AChE inhibitor, 1,5-bis(4-allyldimethylammoniumphenyl)pentan-3-one, indicating the high specificity of AChE towards the novel substrates in a crude tissue sample. From these results, we conclude that the novel compounds developed would be suitable AChE-selective substrates for Ellman's method.  (+info)

Thiocholine is not a medical term per se, but it is a chemical compound that has applications in the medical and biological fields. Thiocholine is the reduced form of thiochrome, which is a derivative of vitamin B1 (thiamine). It is often used as a reagent in biochemical assays to measure the activity of acetylcholinesterase, an enzyme that breaks down the neurotransmitter acetylcholine.

In this context, thiocholine iodide (S-[2-(hydroxyethyl)thio]ethan-1-oniuim iodide) is commonly used as a substrate for acetylcholinesterase. When the enzyme hydrolyzes thiocholine iodide, it produces thiocholine, which can be detected and quantified through its reaction with ferric chloride to form a colored complex. This assay is useful in diagnosing certain neurological conditions or monitoring the effectiveness of treatments that target the cholinergic system.

Acetylthiocholine is a synthetic chemical compound that is widely used in scientific research, particularly in the field of neuroscience. It is the acetylated form of thiocholine, which is a choline ester. Acetylthiocholine is often used as a substrate for enzymes called cholinesterases, including acetylcholinesterase (AChE) and butyrylcholinesterase (BChE).

When Acetylthiocholine is hydrolyzed by AChE, it produces choline and thioacetic acid. This reaction is important because it terminates the signal transduction of the neurotransmitter acetylcholine at the synapse between neurons. Inhibition of AChE can lead to an accumulation of Acetylthiocholine and acetylcholine, which can have various effects on the nervous system, depending on the dose and duration of inhibition.

Acetylthiocholine is also used as a reagent in the Ellman's assay, a colorimetric method for measuring AChE activity. In this assay, Acetylthiocholine is hydrolyzed by AChE, releasing thiocholine, which then reacts with dithiobisnitrobenzoic acid (DTNB) to produce a yellow color. The intensity of the color is proportional to the amount of thiocholine produced and can be used to quantify AChE activity.

Butyrylcholinesterase (BChE) is an enzyme that catalyzes the hydrolysis of esters of choline, including butyrylcholine and acetylcholine. It is found in various tissues throughout the body, including the liver, brain, and plasma. BChE plays a role in the metabolism of certain drugs and neurotransmitters, and its activity can be inhibited by certain chemicals, such as organophosphate pesticides and nerve agents. Elevated levels of BChE have been found in some neurological disorders, while decreased levels have been associated with genetic deficiencies and liver disease.

Cholinesterases are a group of enzymes that play an essential role in the nervous system by regulating the transmission of nerve impulses. They work by breaking down a type of chemical messenger called acetylcholine, which is released by nerves to transmit signals to other nerves or muscles.

There are two main types of cholinesterases: acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). AChE is found primarily in the nervous system, where it rapidly breaks down acetylcholine to terminate nerve impulses. BChE, on the other hand, is found in various tissues throughout the body, including the liver and plasma, and plays a less specific role in breaking down various substances, including some drugs and toxins.

Inhibition of cholinesterases can lead to an accumulation of acetylcholine in the synaptic cleft, which can result in excessive stimulation of nerve impulses and muscle contractions. This effect is exploited by certain medications used to treat conditions such as myasthenia gravis, Alzheimer's disease, and glaucoma, but can also be caused by exposure to certain chemicals or toxins, such as organophosphate pesticides and nerve agents.

Acetylcholinesterase (AChE) is an enzyme that catalyzes the hydrolysis of acetylcholine (ACh), a neurotransmitter, into choline and acetic acid. This enzyme plays a crucial role in regulating the transmission of nerve impulses across the synapse, the junction between two neurons or between a neuron and a muscle fiber.

Acetylcholinesterase is located in the synaptic cleft, the narrow gap between the presynaptic and postsynaptic membranes. When ACh is released from the presynaptic membrane and binds to receptors on the postsynaptic membrane, it triggers a response in the target cell. Acetylcholinesterase rapidly breaks down ACh, terminating its action and allowing for rapid cycling of neurotransmission.

Inhibition of acetylcholinesterase leads to an accumulation of ACh in the synaptic cleft, prolonging its effects on the postsynaptic membrane. This can result in excessive stimulation of cholinergic receptors and overactivation of the cholinergic system, which may cause a range of symptoms, including muscle weakness, fasciculations, sweating, salivation, lacrimation, urination, defecation, bradycardia, and bronchoconstriction.

Acetylcholinesterase inhibitors are used in the treatment of various medical conditions, such as Alzheimer's disease, myasthenia gravis, and glaucoma. However, they can also be used as chemical weapons, such as nerve agents, due to their ability to disrupt the nervous system and cause severe toxicity.

Cholinesterase inhibitors are a class of drugs that work by blocking the action of cholinesterase, an enzyme that breaks down the neurotransmitter acetylcholine in the body. By inhibiting this enzyme, the levels of acetylcholine in the brain increase, which can help to improve symptoms of cognitive decline and memory loss associated with conditions such as Alzheimer's disease and other forms of dementia.

Cholinesterase inhibitors are also used to treat other medical conditions, including myasthenia gravis, a neuromuscular disorder that causes muscle weakness, and glaucoma, a condition that affects the optic nerve and can lead to vision loss. Some examples of cholinesterase inhibitors include donepezil (Aricept), galantamine (Razadyne), and rivastigmine (Exelon).

It's important to note that while cholinesterase inhibitors can help to improve symptoms in some people with dementia, they do not cure the underlying condition or stop its progression. Side effects of these drugs may include nausea, vomiting, diarrhea, and increased salivation. In rare cases, they may also cause seizures, fainting, or cardiac arrhythmias.

... thiocholine MeSH D02.092.877.883.333.800.030 - acetylthiocholine MeSH D02.092.877.883.333.800.200 - butyrylthiocholine MeSH ... thiocholine MeSH D02.675.276.232.800.030 - acetylthiocholine MeSH D02.675.276.232.800.200 - butyrylthiocholine MeSH D02.675. ...
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... and positively charged QDs with thiocholine (THIO-QDs). The size and charge of these two QDs were investigated in three types ...
... thiocholine MeSH D02.092.877.883.333.800.030 - acetylthiocholine MeSH D02.092.877.883.333.800.200 - butyrylthiocholine MeSH ... thiocholine MeSH D02.675.276.232.800.030 - acetylthiocholine MeSH D02.675.276.232.800.200 - butyrylthiocholine MeSH D02.675. ...
... which was hydrolyzed to acetate and thiocholine by esterases in the sample. Thiocholine was reacted with a chromatophore, ...
... the product thiocholine and a nonhydrolysable substrate analogue. These structures provide a series of static snapshots of the ...
This enzyme converts the acetylthiocholine in thiocholine (TC). The TC has a thiol group that spontaneously chemisorbs on the ...
Thiocholine D2.886.489.789. Thioctic Acid D2.241.803. D10.251.941. Thromboembolism C14.907.355.350.850 C14.907.355.590. ...
Thiocholine D2.886.489.789. Thioctic Acid D2.241.803. D10.251.941. Thromboembolism C14.907.355.350.850 C14.907.355.590. ...
Thiocholine D2.886.489.789. Thioctic Acid D2.241.803. D10.251.941. Thromboembolism C14.907.355.350.850 C14.907.355.590. ...
Thiocholine D2.886.489.789. Thioctic Acid D2.241.803. D10.251.941. Thromboembolism C14.907.355.350.850 C14.907.355.590. ...
Thiocholine D2.886.489.789. Thioctic Acid D2.241.803. D10.251.941. Thromboembolism C14.907.355.350.850 C14.907.355.590. ...
Thiocholine D2.886.489.789. Thioctic Acid D2.241.803. D10.251.941. Thromboembolism C14.907.355.350.850 C14.907.355.590. ...
Thiocholine D2.886.489.789. Thioctic Acid D2.241.803. D10.251.941. Thromboembolism C14.907.355.350.850 C14.907.355.590. ...
Thiocholine D2.886.489.789. Thioctic Acid D2.241.803. D10.251.941. Thromboembolism C14.907.355.350.850 C14.907.355.590. ...
Thiocholine D2.886.489.789. Thioctic Acid D2.241.803. D10.251.941. Thromboembolism C14.907.355.350.850 C14.907.355.590. ...
Thiocholine D2.886.489.789. Thioctic Acid D2.241.803. D10.251.941. Thromboembolism C14.907.355.350.850 C14.907.355.590. ...
Thiocholine D2.886.489.789. Thioctic Acid D2.241.803. D10.251.941. Thromboembolism C14.907.355.350.850 C14.907.355.590. ...
butyryl_thiocholine_iodide. *S-butyrylthiocholine_iodide. *(S)-butyrylthiocholine_iodide. Sum Formula: C9H21O1S1N1I1 ...
Specifically, acetylcholinesterase (AChE) hydrolyzes acetylthiocholine into thiocholine (TCh). Subsequently, TCh induces the ...
Hydrolysis of ATCI to thiocholine in presence DTNB; non-enzymatic hydrolysis of ATCI must be subtracted. 1mM DTNB, in 0.1M ...
The COF was able to capture thiocholine by hydrogen bonding. The linear range of the biosensor was 0.39-35 μmol/L with an LOD ... COFTab-Dva nanofibers can effectively immobilize acetylcholine and enrich thiocholine due to their large surface area and ...
Each Ml Contains Cyproheptadine Hcl Ip 1.5mg Thiocholine Citrate 55mg Drops ...
PChE was measured by enzymatic method using butyrate and thiocholine as substrate (5). ...
When let thiocholine reacts with dithiobisnitrobenzoate (DTNB), 2-nitrobenzoate-5-mercaptothiocholine and 5-thio-2- ... A synthetic substrate for AChE, acetylthiocholine iodide (AtCh), is broken down to thiocholine and acetate. ...
Thiocholine (TCh), one of the products of AChE hydrolysis, can be used as a measure of AChE enzymatic activity [49]. TCh also ... Tang, W.; Yang, J.; Wang, F.; Wang, J.; Li, Z. Thiocholine-triggered reaction in personal glucose meters for portable ...
... cyclosarin thiocholine, tabun thiocholine, and carbofuran. / Duysen, Ellen G.; Cashman, John R.; Schopfer, Lawrence M. et al. ... cyclosarin thiocholine, tabun thiocholine, and carbofuran, Chemico-Biological Interactions, vol. 195, no. 3, pp. 189-198. ... cyclosarin thiocholine, tabun thiocholine, and carbofuran. In: Chemico-Biological Interactions. 2012 ; Vol. 195, No. 3. pp. 189 ... cyclosarin thiocholine, tabun thiocholine, and carbofuran. Chemico-Biological Interactions. 2012 Feb 5;195(3):189-198. doi: ...
Their neuromuscular junctions were stained by thiocholine histochemical procedure and myonuclei were fluorescently labeled by ...
The rate of formation of thiocholine from acetylcholine iodide in the presence of tissue cholinesterase was measured using a ... This was measured on the basis of the formation of yellow color due to the reaction of thiocholine with dithiobisnitrobenzoate ...
  • Cholinesterase activity was assessed in two blood samples by measuring the changes in absorbence at 405 nm (EPOS 5060 analyser) resulting when the chromogen 5,5'?dithiobis(4-nitrobenzoic acid) reacts with the thiocholine iodide produced by the action of the enzyme on a highly diluted sample of acetylthiocholine iodide. (dlawer.info)
  • 2 Acetylthiocholine served as the substrate, which was hydrolyzed to acetate and thiocholine by esterases in the sample. (vin.com)
  • Here, we present the crystal structures of Torpedo californica AChE complexed with the substrate acetylthiocholine, the product thiocholine and a nonhydrolysable substrate analogue. (proteopedia.org)
  • These structures provide a series of static snapshots of the substrate en route to the active site and identify, for the first time, binding of substrate and product at both the peripheral and active sites. (proteopedia.org)
  • negatively charged QDs were formed with mercaptopropionic acid (MPA-QDs) and positively charged QDs with thiocholine (THIO-QDs). (cdc.gov)
  • Thiocholine was reacted with a chromatophore, dithiodinitrobenzoic acid (DTNB), to produce the yellow 5-thio-2-nitrobenzoic acid. (vin.com)
  • Three months postoperatively the animals were perfused and their brains processed by direct thiocholine method for ch olinesterases (Ch), specific acetylcholinesterase (AChE) and nonspecific butyrylcholinesterase (BuChE) or stained by Cresyl violet. (iospress.com)
  • 14. Development of an acetylcholinesterase immobilized flow through amperometric detector based on thiocholine detection at a silver electrode. (nih.gov)
  • Thiocholine reacts with hexacyanoferrate ion in the working solution and the reduction of [Fe(CN) 6 ] -3 to [Fe(CN) 6 ] -4 and its subsequent reoxidization by the electrode generates very sharp, rapid and reproducible electric signals. (tau.ac.il)