Acetylthiocholine: An agent used as a substrate in assays for cholinesterases, especially to discriminate among enzyme types.Acetylcholinesterase: 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.CholinesterasesTetraisopropylpyrophosphamide: N,N',N'',N'''-Tetraisopropylpyrophosphamide. A specific inhibitor of pseudocholinesterases. It is commonly used experimentally to determine whether pseudo- or acetylcholinesterases are involved in an enzymatic process.Cholinesterase Inhibitors: 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.Thiocholine: A mercaptocholine used as a reagent for the determination of CHOLINESTERASES. It also serves as a highly selective nerve stain.Butyrylcholinesterase: An aspect of cholinesterase (EC 3.1.1.8).Hydrolysis: The process of cleaving a chemical compound by the addition of a molecule of water.Kinetics: The rate dynamics in chemical or physical systems.Substrate Specificity: A characteristic feature of enzyme activity in relation to the kind of substrate on which the enzyme or catalytic molecule reacts.Research Report: Detailed account or statement or formal record of data resulting from empirical inquiry.Databases, Protein: Databases containing information about PROTEINS such as AMINO ACID SEQUENCE; PROTEIN CONFORMATION; and other properties.Internet: A loose confederation of computer communication networks around the world. The networks that make up the Internet are connected through several backbone networks. The Internet grew out of the US Government ARPAnet project and was designed to facilitate information exchange.User-Computer Interface: The portion of an interactive computer program that issues messages to and receives commands from a user.Software: Sequential operating programs and data which instruct the functioning of a digital computer.ArchivesProteins: Linear POLYPEPTIDES that are synthesized on RIBOSOMES and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits. The specific sequence of AMINO ACIDS determines the shape the polypeptide will take, during PROTEIN FOLDING, and the function of the protein.Sydnones: OXADIAZOLES bearing an oxygen at the 5-position. They are mesoionic, with delocalized positive and negative charges.IndazolesThiophenesPatents as Topic: Exclusive legal rights or privileges applied to inventions, plants, etc.Cyclization: Changing an open-chain hydrocarbon to a closed ring. (McGraw-Hill Dictionary of Scientific and Technical Terms, 5th ed)Benzo(a)pyrene: A potent mutagen and carcinogen. It is a public health concern because of its possible effects on industrial workers, as an environmental pollutant, an as a component of tobacco smoke.Memory Disorders: Disturbances in registering an impression, in the retention of an acquired impression, or in the recall of an impression. Memory impairments are associated with DEMENTIA; CRANIOCEREBRAL TRAUMA; ENCEPHALITIS; ALCOHOLISM (see also ALCOHOL AMNESTIC DISORDER); SCHIZOPHRENIA; and other conditions.PubMed: A bibliographic database that includes MEDLINE as its primary subset. It is produced by the National Center for Biotechnology Information (NCBI), part of the NATIONAL LIBRARY OF MEDICINE. PubMed, which is searchable through NLM's Web site, also includes access to additional citations to selected life sciences journals not in MEDLINE, and links to other resources such as the full-text of articles at participating publishers' Web sites, NCBI's molecular biology databases, and PubMed Central.Periodicals as Topic: A publication issued at stated, more or less regular, intervals.BooksPublishing: "The business or profession of the commercial production and issuance of literature" (Webster's 3d). It includes the publisher, publication processes, editing and editors. Production may be by conventional printing methods or by electronic publishing.MEDLINE: The premier bibliographic database of the NATIONAL LIBRARY OF MEDICINE. MEDLINE® (MEDLARS Online) is the primary subset of PUBMED and can be searched on NLM's Web site in PubMed or the NLM Gateway. MEDLINE references are indexed with MEDICAL SUBJECT HEADINGS (MeSH).Protein Array Analysis: Ligand-binding assays that measure protein-protein, protein-small molecule, or protein-nucleic acid interactions using a very large set of capturing molecules, i.e., those attached separately on a solid support, to measure the presence or interaction of target molecules in the sample.Proteomics: The systematic study of the complete complement of proteins (PROTEOME) of organisms.Proteome: The protein complement of an organism coded for by its genome.Autoantibodies: Antibodies that react with self-antigens (AUTOANTIGENS) of the organism that produced them.Phase Transition: A change of a substance from one form or state to another.Oligonucleotide Array Sequence Analysis: Hybridization of a nucleic acid sample to a very large set of OLIGONUCLEOTIDE PROBES, which have been attached individually in columns and rows to a solid support, to determine a BASE SEQUENCE, or to detect variations in a gene sequence, GENE EXPRESSION, or for GENE MAPPING.Databases, Chemical: Databases devoted to knowledge about specific chemicals.Amphotericin B: Macrolide antifungal antibiotic produced by Streptomyces nodosus obtained from soil of the Orinoco river region of Venezuela.Culture Media: Any liquid or solid preparation made specifically for the growth, storage, or transport of microorganisms or other types of cells. The variety of media that exist allow for the culturing of specific microorganisms and cell types, such as differential media, selective media, test media, and defined media. Solid media consist of liquid media that have been solidified with an agent such as AGAR or GELATIN.Epithelial Cells: Cells that line the inner and outer surfaces of the body by forming cellular layers (EPITHELIUM) or masses. Epithelial cells lining the SKIN; the MOUTH; the NOSE; and the ANAL CANAL derive from ectoderm; those lining the RESPIRATORY SYSTEM and the DIGESTIVE SYSTEM derive from endoderm; others (CARDIOVASCULAR SYSTEM and LYMPHATIC SYSTEM) derive from mesoderm. Epithelial cells can be classified mainly by cell shape and function into squamous, glandular and transitional epithelial cells.Cell Line: Established cell cultures that have the potential to propagate indefinitely.Pyruvic Acid: An intermediate compound in the metabolism of carbohydrates, proteins, and fats. In thiamine deficiency, its oxidation is retarded and it accumulates in the tissues, especially in nervous structures. (From Stedman, 26th ed)Streptomycin: An antibiotic produced by the soil actinomycete Streptomyces griseus. It acts by inhibiting the initiation and elongation processes during protein synthesis.Hepatitis, Infectious Canine: A contagious disease caused by canine adenovirus (ADENOVIRUSES, CANINE) infecting the LIVER, the EYE, the KIDNEY, and other organs in dogs, other canids, and bears. Symptoms include FEVER; EDEMA; VOMITING; and DIARRHEA.Glycogen Phosphorylase, Muscle Form: An isoenzyme of GLYCOGEN PHOSPHORYLASE that catalyzes the degradation of GLYCOGEN in muscle. Mutation of the gene coding this enzyme is the cause of McArdle disease (GLYCOGEN STORAGE DISEASE TYPE V).Dog Diseases: Diseases of the domestic dog (Canis familiaris). This term does not include diseases of wild dogs, WOLVES; FOXES; and other Canidae for which the heading CARNIVORA is used.Muscles: Contractile tissue that produces movement in animals.Dogs: The domestic dog, Canis familiaris, comprising about 400 breeds, of the carnivore family CANIDAE. They are worldwide in distribution and live in association with people. (Walker's Mammals of the World, 5th ed, p1065)Paraoxon: An organophosphate cholinesterase inhibitor that is used as a pesticide.Organophosphate Poisoning: Poisoning due to exposure to ORGANOPHOSPHORUS COMPOUNDS, such as ORGANOPHOSPHATES; ORGANOTHIOPHOSPHATES; and ORGANOTHIOPHOSPHONATES.Spectrophotometry, Ultraviolet: Determination of the spectra of ultraviolet absorption by specific molecules in gases or liquids, for example Cl2, SO2, NO2, CS2, ozone, mercury vapor, and various unsaturated compounds. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Undaria: A genus of BROWN ALGAE, in the family Alariaceae, native to Japan, Korea, and China. The edible SEAWEED Undaria pinnatifida is also called wakame.Databases, Factual: Extensive collections, reputedly complete, of facts and data garnered from material of a specialized subject area and made available for analysis and application. The collection can be automated by various contemporary methods for retrieval. The concept should be differentiated from DATABASES, BIBLIOGRAPHIC which is restricted to collections of bibliographic references.Database Management Systems: Software designed to store, manipulate, manage, and control data for specific uses.Databases, Genetic: Databases devoted to knowledge about specific genes and gene products.

Histochemically distinct compartments in the striatum of human, monkeys, and cat demonstrated by acetylthiocholinesterase staining. (1/38)

We here report observations on the distribution of acetylcholinesterase (acetylcholine hydrolase, EC 3.1.1.7) in the striatum of the adult human, the rhesus monkey, and the cat. By the histochemical staining methods of Geneser-Jensen and Blackstad and of Karnovsky and Roots, compartments of low cholinesterase activity were identified in parts of the striatum in all three species. In frontal sections, these enzyme-poor zones appeared as a variable number of weakly stained approximately 0.5-mm-wide zones embedded in a darkly stained background. The zones varied in cross-sectional shape from round to elongated and were sometimes branched. They were most prominent in the head of the caudate nucleus. Three-dimensional reconstructions of serial sections through the caudate nucleus in the human and cat suggest that over distances of at least several millimeters, the zones of low enzyme activity form nearly continuous labyrinths.  (+info)

Determinants of substrate specificity of a second non-neuronal secreted acetylcholinesterase from the parasitic nematode Nippostrongylus brasiliensis. (2/38)

We recently reported on a non-neuronal secreted acetylcholinesterase (AChE B) from the nematode parasite Nippostrongylus brasiliensis. Here we describe the primary structure and enzymatic properties of a second secreted variant, termed AChE C after the designation of native AChE isoforms from this parasite. As for the former enzyme, AChE C is truncated at the carboxyl terminus in comparison with the Torpedo AChE, and three of the 14 aromatic residues that line the active site gorge are substituted by nonaromatic residues, corresponding to Tyr70 (Ser), Trp279 (Asn) and Phe288 (Met). A recombinant form of AChE C was highly expressed by Pichia pastoris. The enzyme was monomeric and hydrophilic, and displayed a marked preference for acetylthiocholine as substrate. A double mutation (W302F/W345F, corresponding to positions 290 and 331 in Torpedo) rendered the enzyme 10-fold less sensitive to excess substrate inhibition and two times less susceptible to the bis quaternary inhibitor BW284C51, but did not radically affect substrate specificity or sensitivity to the 'peripheral site' inhibitor propidium iodide. In contrast, a triple mutant (M300G/W302F/W345F) efficiently hydrolysed propionylthiocholine and butyrylthiocholine in addition to acetylthiocholine, while remaining insensitive to the butyrylcholinesterase-specific inhibitor iso-OMPA and displaying a similar profile of excess substrate inhibition as the double mutant. These data highlight a conserved pattern of active site architecture for nematode secreted AChEs characterized to date, and provide an explanation for the substrate specificity that might otherwise appear inconsistent with the primary structure in comparison to other invertebrate AChEs.  (+info)

High-resolution optical mapping of the right bundle branch in connexin40 knockout mice reveals slow conduction in the specialized conduction system. (3/38)

Connexin40 (Cx40) is a major gap junction protein that is expressed in the His-Purkinje system and thought to be a critical determinant of cell-to-cell communication and conduction of electrical impulses. Video maps of the ventricular epicardium and the proximal segment of the right bundle branch (RBB) were obtained using a high-speed CCD camera while simultaneously recording volume-conducted ECGs. In Cx40(-/-) mice, the PR interval was prolonged (47.4+/-1.4 in wild-type [WT] [n=6] and 57.5+/-2.8 in Cx40(-/-) [n=6]; P<0.01). WT ventricular epicardial activation was characterized by focused breakthroughs that originated first on the right ventricle (RV) and then the left ventricle (LV). In Cx40(-/-) hearts, the RV breakthrough occurred after the LV breakthrough. Additionally, Cx40(-/-) mice showed RV breakthrough times that were significantly delayed with respect to QRS complex onset (3.7+/-0.7 ms in WT [n=6] and 6.5+/-0.7 ms in Cx40(-/-) [n=6]; P<0.01), whereas LV breakthrough times did not change. Conduction velocity measurements from optical mapping of the RBB revealed slow conduction in Cx40(-/-) mice (74.5+/-3 cm/s in WT [n=7] and 43.7+/-6 cm/s in Cx40(-/-) [n=7]; P<0.01). In addition, simultaneous ECG records demonstrated significant delays in Cx40(-/-) RBB activation time with respect to P time (P-RBB time; 41.6+/-1.9 ms in WT [n=7] and 55.1+/-1.3 ms in [n=7]; P<0.01). These data represent the first direct demonstration of conduction defects in the specialized conduction system of Cx40(-/-) mice and provide new insight into the role of gap junctions in cardiac impulse propagation.  (+info)

Action potential characteristics and arrhythmogenic properties of the cardiac conduction system of the murine heart. (4/38)

Studies have characterized conduction velocity in the right and left bundle branches (RBB, LBB) of normal and genetically engineered mice. However, no information is available on the action potential characteristics of the specialized conduction system (SCS). We have used microelectrode techniques to characterize action potential properties of the murine SCS, as well as epicardial and endocardial muscle preparations for comparison. In the RBB, action potential duration at 50%, 70%, and 90% repolarization (APD(50,70,90)) was 6+/-0.7, 35+/-6, and 90+/-7 ms, respectively. Maximum upstroke velocity (dV/dt(max)) was 153+/-14 V/s, and conduction velocity averaged 0.85+/-0.2 m/s. APD(90) was longer in the Purkinje network of fibers (web) than in the RBB (P<0.01). Web APD(50) was longer in the left than in the right ventricle (P<0.05). Yet, web APD(90) was longer in the right than in the left ventricle (P<0.001). APD(50,70) was significantly longer in the endocardial than in the epicardial (P<0.001; P<0.003). APD(90) in the epicardial and endocardial was shorter than in the RBB ( approximately 36 ms versus approximately 100 ms). Spontaneous electrical oscillations in phase 2 of the SCS occasionally resulted in early afterdepolarizations. These results demonstrate that APDs in the murine SCS are significantly ( approximately 2-fold) longer than in the myocardium and implicate the role of the murine SCS in arrhythmias. The differences should have important implications in the use of the mouse heart to study excitation, propagation, and arrhythmias.  (+info)

Reversibly bound and covalently attached ligands induce conformational changes in the omega loop, Cys69-Cys96, of mouse acetylcholinesterase. (5/38)

We have used a combination of cysteine substitution mutagenesis and site-specific labeling to characterize the structural dynamics of mouse acetylcholinesterase (mAChE). Six cysteine-substituted sites of mAChE (Leu(76), Glu(81), Glu(84), Tyr(124), Ala(262), and His(287)) were labeled with the environmentally sensitive fluorophore, acrylodan, and the kinetics of substrate hydrolysis and inhibitor association were examined along with spectroscopic characteristics of the acrylodan-conjugated, cysteine-substituted enzymes. Residue 262, being well removed from the active center, appears unaffected by inhibitor binding. Following the binding of ligand, hypsochromic shifts in emission of acrylodan at residues 124 and 287, located near the perimeter of the gorge, reflect the exclusion of solvent and a hydrophobic environment created by the associated ligand. By contrast, the bathochromic shifts upon inhibitor binding seen for acrylodan conjugated to three omega loop (Omega loop) residues 76, 81, and 84 reveal that the acrylodan side chains at these positions are displaced from a hydrophobic environment and become exposed to solvent. The magnitude of fluorescence emission shift is largest at position 84 and smallest at position 76, indicating that a concerted movement of residues on the Omega loop accompanies gorge closure upon ligand binding. Acrylodan modification of substituted cysteine at position 84 reduces ligand binding and steady-state kinetic parameters between 1 and 2 orders of magnitude, but a similar substitution at position 81 only minimally alters the kinetics. Thus, combined kinetic and spectroscopic analyses provide strong evidence that conformational changes of the Omega loop accompany ligand binding.  (+info)

Asymmetric distribution of acetylcholinesterase in gravistimulated maize seedlings. (6/38)

Acetylcholinesterase (AChE) activity has previously been studied by this laboratory and shown to occur at the interface between the stele and cortex of the mesocotyl of maize (Zea mays L.) seedlings. In this work we studied the distribution of AChE activity in 5-d-old maize seedlings following a gravity stimulus. After the stimulus, we found an asymmetric distribution of the enzyme in the coleoptile, the coleoptile node, and the mesocotyl of the stimulated seedlings using both histochemical and colorimetric methods for measuring the hydrolysis of acetylthiocholine. The hydrolytic capability of the esterase was greater on the lower side of the horizontally placed seedlings. Using the histochemical method, we localized the hydrolytic capability in the cortical cells around the vascular stele of the tissues. The hydrolytic activity was inhibited 80 to 90% by neostigmine, an inhibitor of AChE. When neostigmine was applied to the corn kernel, the gravity response of the seedling was inhibited and no enzyme-positive spots appeared in the gravity-stimulated seedlings. We believe these results indicate a role for AChE in the gravity response of maize seedlings.  (+info)

Studies of the acetylcholinesterase from houseflies (Musca domestica L.) resistant and susceptible to organophosphorus insecticides. (7/38)

Acetylcholinesterase from the heads of insecticide-resistant and -susceptible houseflies (Musca domestica L.) was studied in vitro. The enzymes could not be distinguished electrophoretically, and their behaviour on polyacrylamide-disc-gel electrophoresis was influenced by the presence of Triton X-100 in both the homogenate and the gels. In the absence of detergent, the acetylcholinesterase was heterogeneous, but behaved as a single enzyme when it was present. By analogy with studies of acetylcholinesterase from other sources, these observations were attributed to aggregation of the enzyme when not bound by membranes. The enzyme from resistant flies was more slowly inhibited than the susceptible enzyme, bimolecular rate constants (ki) differing by approx. 4-20-fold for a range of organophosphorus compounds. The kinetics of inhibition of acetylcholinesterase were consistent with the results of electrophoresis, i.e. they corresponded to those of a single enzyme in the presence of Triton X-100, but a mixture of enzymes in its absence. The susceptibility of the more sensitive components in these mixtures was determined.  (+info)

Substrate activation in acetylcholinesterase induced by low pH or mutation in the pi-cation subsite. (8/38)

Substrate inhibition is considered a defining property of acetylcholinesterase (AChE), whereas substrate activation is characteristic of butyrylcholinesterase (BuChE). To understand the mechanism of substrate inhibition, the pH dependence of acetylthiocholine hydrolysis by AChE was studied between pH 5 and 8. Wild-type human AChE and its mutants Y337G and Y337W, as well as wild-type Bungarus fasciatus AChE and its mutants Y333G, Y333A and Y333W were studied. The pH profile results were unexpected. Instead of substrate inhibition, wild-type AChE and all mutants showed substrate activation at low pH. At high pH, there was substrate inhibition for wild-type AChE and for the mutant with tryptophan in the pi-cation subsite, but substrate activation for mutants containing small residues, glycine or alanine. This is particularly apparent in the B. fasciatus AChE. Thus a single amino acid substitution in the pi-cation site, from the aromatic tyrosine of B. fasciatus AChE to the alanine of BuChE, caused AChE to behave like BuChE. Excess substrate binds to the peripheral anionic site (PAS) of AChE. The finding that AChE is activated by excess substrate supports the idea that binding of a second substrate molecule to the PAS induces a conformational change that reorganizes the active site.  (+info)

Numerous amperometric biosensors have been developed for the fast analysis of neurotoxic insecticides based on inhibition of cholinesterase (AChE). The analytical signal is quantified by the oxidation of the thiocholine that is produced enzymatically by the hydrolysis of the acetylthiocholine pseudosubstrate. The pseudosubstrate is a cation and it is associated with chloride or iodide as corresponding anion to form a salt. The iodide salt is cheaper, but it is electrochemically active and consequently more difficult to use in electrochemical analytical devices. We investigate the possibility of using acetylthiocholine iodide as pseudosubstrate for amperometric detection. Our investigation demonstrates that operational conditions for any amperometric biosensor that use acetylthiocholine iodide must be thoroughly optimized to avoid false analytical signals or a reduced sensitivity. The working overpotential determined for different screen-printed electrodes was: carbon-nanotubes (360 mV), platinum (560
Hydrolysis of acetylcholine catalyzed by acetylcholinesterase (AChE), one of the most efficient enzymes in nature, occurs at the base of a deep and narrow active center gorge. At the entrance of the gorge, the peripheral anionic site provides a binding locus for allosteric ligands, including substrates. To date, no structural information on substrate entry to the active center from the peripheral site of AChE or its subsequent egress has been reported. Complementary crystal structures of mouse AChE and an inactive mouse AChE mutant with a substituted catalytic serine (S203A), in various complexes with four substrates (acetylcholine, acetylthiocholine, succinyldicholine, and butyrylthiocholine), two non-hydrolyzable substrate analogues (m-(N,N,N-trimethylammonio)-trifluoroacetophenone and 4-ketoamyltrimethylammonium), and one reaction product (choline) were solved in the 2.05-2.65-A resolution range. These structures, supported by binding and inhibition data obtained on the same complexes, reveal ...
Dephosphorylation of the E2P phosphoenzyme intermediate of the sarcoplasmic reticulum Ca2+-ATPase was studied using density functional theory. The hydrolysis reaction proceeds via a nucleophilic attack on the phosphorylated residue Asp351 by a water molecule, which is positioned by the nearby residue Glu183 acting as a base. The activation barrier was calculated to be 14.3 kcal/mol, which agrees well with values of 15-17 kcal/mol derived from experimentally observed rates. The optimized structure of the transition state reveals considerable bond breakage between phosphorus and the Asp351 oxygen (distance 2.19 angstrom) and little bond formation to the attacking water oxygen (distance 2.26 angstrom). Upon formation of the singly protonated phosphate product, Glu183 becomes protonated. The bridging aspartyl phosphate oxygen approaches Lys684 progressively when proceeding from the reactant state (distance 1.94 angstrom) via the transition state (1.78 angstrom) to the product state (1.58 angstrom). ...
Dephosphorylation of the E2P phosphoenzyme intermediate of the sarcoplasmic reticulum Ca2+-ATPase was studied using density functional theory. The hydrolysis reaction proceeds via a nucleophilic attack on the phosphorylated residue Asp351 by a water molecule, which is positioned by the nearby residue Glu183 acting as a base. The activation barrier was calculated to be 14.3 kcal/mol, which agrees well with values of 15-17 kcal/mol derived from experimentally observed rates. The optimized structure of the transition state reveals considerable bond breakage between phosphorus and the Asp351 oxygen (distance 2.19 angstrom) and little bond formation to the attacking water oxygen (distance 2.26 angstrom). Upon formation of the singly protonated phosphate product, Glu183 becomes protonated. The bridging aspartyl phosphate oxygen approaches Lys684 progressively when proceeding from the reactant state (distance 1.94 angstrom) via the transition state (1.78 angstrom) to the product state (1.58 angstrom). ...
TY - JOUR. T1 - Substrate activation in acetylcholinesterase induced by low pH or mutation in the π-cation subsite. AU - Masson, Patrick. AU - Schopfer, Lawrence M. AU - Bartels, Cynthia F.. AU - Froment, Marie Thérèse. AU - Ribes, Fabien. AU - Nachon, Florian. AU - Lockridge, Oksana. PY - 2002/2/11. Y1 - 2002/2/11. N2 - Substrate inhibition is considered a defining property of acetylcholinesterase (AChE), whereas substrate activation is characteristic of butyrylcholinesterase (BuChE). To understand the mechanism of substrate inhibition, the pH dependence of acetylthiocholine hydrolysis by AChE was studied between pH 5 and 8. Wild-type human AChE and its mutants Y337G and Y337W, as well as wild-type Bungarus fasciatus AChE and its mutants Y333G, Y333A and Y333W were studied. The pH profile results were unexpected. Instead of substrate inhibition, wild-type AChE and all mutants showed substrate activation at low pH. At high pH, there was substrate inhibition for wild-type AChE and for the ...
The pharmacological function of heroin requires an activation process that transforms heroin into 6-monoacetylmorphine (6-MAM), which is the most active form. The primary enzyme responsible for this activation process in human plasma is butyrylcholinesterase (BChE). The detailed reaction pathway of the activation process via BChE-catalyzed hydrolysis has been explored computationally, for the first time, in this study via molecular dynamics simulation and first-principles quantum mechanical/molecular mechanical free energy calculations. It has been demonstrated that the whole reaction process includes acylation and deacylation stages. The acylation consists of two reaction steps, i.e., the nucleophilic attack on the carbonyl carbon of the 3-acetyl group of heroin by the hydroxyl oxygen of the Ser198 side chain and the dissociation of 6-MAM. The deacylation also consists of two reaction steps, i.e., the nucleophilic attack on the carbonyl carbon of the acyl enzyme intermediate by a water molecule ...
While the inhibition of cholinesterase (ChE) activity as a biomarker of exposure to neurotoxic insecticides is well established in aquatic invertebrates of temperate areas, little is known about organisms from polar regions including Antarctica. Cholinesterase activity was investigated in specimens of the Antarctic scallop, Adamussium colbecki, collected in winter 2000 at Campo Icaro (Ross Sea, Antarctica) for preliminary characterization of a potentially new biomarker. Characterization of various ChE enzymes using specific substrates including an acetylthiocholine iodide (ASCh) and a butyrylthiocholine iodide (BSCh) was performed in gills, digestive gland and adductor muscle of the scallop. The effect of in vivo Zn2þ exposure in gills and digestive gland of A. colbecki was also studied. All the tissues expressed ChE activity (gill,adductor muscle,digestive gland) in accordance with data reported for marine mussels (Mytilus sp.) from temperate areas (1.1-13.8 nmol min1 mg protein1). Significant ...
2 Recep Tayyip Erdoğan University, Department of Fisheries and Aquatic Sciences, Rize, Turkey DOI : 10.4194/1303-2712-v14_3_06 Viewed : 2911 - Downloaded : 3126 Present study was conducted to determine the effects of long term carbosulfan exposure on erythrocyte and liver acetylcholinesterase (AChE) activity in rainbow trout (Oncorhynchus mykiss), and to assess sensitive tissue to carbosulfan in terms of AChE activity. For these purpose, fish were allowed to recover in toxicant-free water for 24 days after 60 days of exposure. AChE activity was determined spectrophotometrically using acetylthiocholine iodide as substrate in the erythrocyte and liver. Erythrocyte and liver AChE of carbosulfan-exposed fish showed considerable inhibition rate. A higher degree of enzyme inhibition was observed in the erythrocyte when compared with liver. The degree of enzyme inhibition had a positive correlation with the time of exposure. Erythrocyte and liver AChE activities were recovered after 18 d and 21 d, ...
5. Nguyen D, Helms V, Lee PH: PRIMSIPLR: Prediction of inner-membrane situated pore-lining residues for alpha-helical transmembrane proteins. Proteins 2014: (in press).. 4. Zhukovsky MA, Lee PH, Ott A, Helms V: Putative cholesterol-binding sites in human immunodeficiency virus (HIV) coreceptors CXCR4 and CCR5. Proteins 2013, 81(4):555-567.. 3. Lee PH, Helms V, Geyer T: Coarse-grained Brownian dynamics simulations of protein translocation through nanopores. J Chem Phys 2012, 137(14).. 2. Lee PH, Helms V: Identifying continuous pores in protein structures with PROPORES by computational repositioning of gating residues. Proteins 2012, 80(2):421-432.. 1. Lee PH, Kuo KL, Chu PY, Liu EM, Lin JH: SLITHER: a web server for generating contiguous conformations of substrate molecules entering into deep active sites of proteins or migrating through channels in membrane transporters. Nucleic Acids Res 2009, 37:W559-W564.. ...
The peripheral anionic site on acetylcholinesterase (AChE), located at the active center gorge entry, encompasses overlapping binding sites for allosteric activators and inhibitors; yet, the molecular mechanisms coupling this site to the active center at the gorge base to modulate catalysis remain unclear. The peripheral site has also been proposed to be involved in heterologous protein associations occurring during synaptogenesis or upon neurodegeneration. A novel crystal form of mouse AChE, combined with spectrophotometric analyses of the crystals, enabled us to solve unique structures of AChE with a free peripheral site, and as three complexes with peripheral site inhibitors: the phenylphenanthridinium ligands, decidium and propidium, and the pyrogallol ligand, gallamine, at 2.20-2.35 A resolution. Comparison with structures of AChE complexes with the peptide fasciculin or with organic bifunctional inhibitors unveils new structural determinants contributing to ligand interactions at the ...
Edit (09/07/17): Sorry for the long quiet interval. It was (partly) due to the fact that I took some time to refine some the code and the arguments in this and the previous post and put it into a paper, of which there is a preprint available as of today: http://arxiv.org/abs/1709.02341 :) Edit (11/14/18): A thoroughly…
Edit (09/07/17): Sorry for the long quiet interval. It was (partly) due to the fact that I took some time to refine some the code and the arguments in this and the previous post and put it into a paper, of which there is a preprint available as of today: http://arxiv.org/abs/1709.02341 :) Edit (11/14/18): A thoroughly…
A cholinesterase based biosensor was constructed in order to assess the effects of ionizing radiation on exposed AChE. Although the primary objective of the experiment was to investigate the effect of ionizing radiation on the activity of the biosensor, no changes in cholinesterase activity were observed. Current provided by oxidation of thiocholine previously created from acetylthiocholine by enzyme catalyzed reaction was in a range 395-455 nA. No significant influence of radiation on AChE activity was found, despite the current variation. However, a surprising phenomenon was observed when a model organophosphate paraoxon was assayed. Irradiated biosensors seem to be more susceptible to the inhibitory effects of paraoxon. Control biosensors provided a 94 ± 5 nA current after exposure to 1 ppm paraoxon. The biosensors irradiated by a 5 kGy radiation dose and exposed to paraoxon provided a current of 49 ± 6 nA. Irradiation by doses ranging from 5 mGy to 100 kGy were investigated and the mentioned
Morel, N., S. Bon, H. M. Greenblatt, D. Van Belle, S. J. Wodak, J. L. Sussman, J. Massoulié, and I. Silman, Effect of mutations within the peripheral anionic site on the stability of acetylcholinesterase., Mol Pharmacol, vol. 55, issue 6, pp. 982-92, 1999 Jun. ...
BioAssay record AID 309555 submitted by ChEMBL: Inhibition of partially purified Sprague-Dawley rat FAAH assessed as substrate hydrolysis.
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Background: Neuropsychological studies have extensively described the presence of cognitive dysfunction in MS patients. One possible pharmacological treatment of the impairment could be based on acetylcholinesterase inhibitors (AChEIs), which have sh
HUP 13 is an analogue of huperzine A with comparable inhibitory action on acetylcholinesterase, but less inhibitory effect on butyrylcholinesterase. HUP 13 is
Comparison between the Acetylcholinesterases of Helix Blood and Cobra Venom. I. The Hydrolysis of Acetylcholine and Its Inhibition by Various Compounds.. Augustinsson, Klas-Bertil ...
Gentaur molecular products has all kinds of products like :search , Arbor \ Acetylcholinesterase Standard, 225UL \ C046-225UL for more molecular products just contact us
Acetylcholinesterase小鼠单克隆抗体[HR2](ab2803)可与小鼠, 兔, 豚鼠, 牛, 猫, 人, 猕猴样本反应并经IP, ELISA, IHC, Flow Cyt, ICC/IF实验严格验证,被3篇文献引用。
乙醯膽鹼酯酶[1](英語:Acetylcholinesterase,簡稱為AChE,EC 3.1.1.7)是一種降解(通過其水解活性)神經遞質乙醯膽鹼成為膽鹼和乙酸的酶。該酶主要存在於神經肌肉接頭與膽鹼能神經系統中,在這些地方該酶的活性就是為了終止突觸傳遞。乙醯膽鹼酯酶具有極高的水解活性--每秒鐘一分子的乙醯膽鹼酯酶可以水解25000分子的乙醯膽鹼。經乙醯膽鹼酯酶作用而產生的膽鹼被重新利用--通過重攝取被轉運進入神經末梢,在那裡被重新利用以合成新的乙醯膽鹼分子[2]。. ...
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100 µg purified IgG, lyophilized. Albumin and azide were added for stabilization. For reconstitution add 100 µl H2O to get a 1mg/ml solution in PBS. Then aliquot and store at -20°C until use ...
TY - JOUR. T1 - Simple general acid-base catalysis of physiological acetylcholinesterase reactions. AU - Pryor, Alton N.. AU - Selwood, Trevor. AU - Leu, Lee Shan. AU - Andracki, Mark A.. AU - Lee, Bong Ho. AU - Rao, Muralikrishna. AU - Rosenberry, Terrone. AU - Doctor, Bhupendra P.. AU - Silman, Israel. AU - Quinn, Daniel M.. PY - 1992/5/6. Y1 - 1992/5/6. N2 - Elements of transition-state stabilization by proton bridging have been characterized by measuring solvent isotope effects and proton inventories for hydrolyses of (acetylthio)choline (ATCh), (propionylthio)choline (PrTCh), and (butyrylthio)choline (BuTCh) catalyzed by acetylcholinesterases (AChEs) from Electrophorus electricus, fetal bovine serum, human erythrocytes, and Torpedo californica. For the Electrophorus enzyme, the acylation rate constant, kcat/Km {= (V/K)/[E]T}, decreases in the order ATCh , PrTCh ≫ BuTCh. Solvent isotope effects for V/K of ATCh hydrolysis are usually within experimental error of unity, which is consistent ...
Using low energy electron (LEE) as a catalyst, the electronic origin of the catalytic strategies corresponding to substrate selectivity, reaction specificity and reaction rate enhancement are investigated for a reversible unimolecular elementary reaction. An electronic energy complementarity between the catalyst and the substrate molecule is the origin of substrate selectivity and reaction specificity. The electronic energy complementarity is induced by tuning the electronic energy of the catalyst. The energy complementarity maximizes the binding forces between the catalyst and the molecule. Consequently, a new electronically metastable high-energy reactant state and a corresponding new low barrier reaction path are resonantly created for a specific reaction of the substrate through the formation of a catalyst-substrate transient adduct. The LEE catalysis also reveals a fundamental \textit{structure-energy correspondence} in the formation of the catalyst-substrate transient adduct. Since the ...
The researchers) demonstrate that the active component of marijuana, Delta9-tetrahydrocannabinol (THC), competitively inhibits the enzyme acetylcholinesterase (AChE) as well as prevents AChE-induced amyloid beta-peptide (Abeta) aggregation, the key pathological marker of Alzheimers disease. Computational modeling of the THC-AChE interaction revealed that THC binds in the peripheral anionic site of AChE, the critical region involved in amyloidgenesis. Compared to currently approved drugs prescribed for the treatment of Alzheimers disease, THC is a considerably superior inhibitor of Abeta aggregation, and this study provides a previously unrecognized molecular mechanism through which cannabinoid molecules may directly impact the progression of this debilitating disease. ...
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Butyrylcholinesterase [BuChE (acylcholine acyl hydrolase); EC 3.1.1.8] limits the access of drugs, including tacrine, to other proteins. The atypical BuChE variant, in which Asp70 at the rim of the active site gorge is substituted by glycine, displayed a more drastically weakened interaction with tacrine than with cocaine, dibucaine, succinylcholine, BW284c51 [1,5-bis(4-allyldimethylammoniumphenyl)pentan-3-one dibromide], or alpha-solanine. To delineate the protein domains that are responsible for this phenomenon, we mutated residues within the rim of the active site gorge, the region parallel to the peripheral site in the homologous enzyme acetylcholinesterase [AChE (acetylcholine acetyl hydrolase); EC 3.1.1.7], the oxyanion hole, and the choline-binding site. When expressed in microinjected Xenopus laevis oocytes, all mutant DNAs yielded comparable amounts of immunoreactive protein products. Most mutants retained catalytic activity close to that of wild-type BuChE and were capable of binding ligands
Photochromic cholinesterase inhibitors were obtained from cis-1,2-α-dithienylethene-based compounds by incorporating one or two aminopolymethylene tacrine groups. All target compounds are potent acetyl- (AChE) and butyrylcholinesterase (BChE) inhibitors in the nanomolar concentration range. Compound 11b bearing an octylene linker exhibited interactions with both the catalytic active site (CAS) and the peripheral anionic site (PAS) of AChE. Yet upon irradiation with light, the mechanism of interaction varied from one photochromic form to another, which was investigated by kinetic studies and proved "photoswitchable". The AChE-induced β-amyloid (Aβ) aggregation assay gave further experimental support to this finding: Aβ1-40 aggregation catalyzed by the PAS of AChE might be inhibited by compound 11b in a concentration-dependent manner and seems to occur only with one photochromic form. Computational docking studies provided potential binding modes of the compound. Docking studies and molecular ...
Characterization and gene cloning of acetylecholinesterase (AChE) in the insecticide-resistant (R) and -susceptible (S) insects have been reported in the past. However, the studies focused mostly on herbivorous pests, rather than predacious species, such as ladybird beetles. Using R and S Propylaea japonica (thunberg), a full-length cDNA sequence (2928 bp) of the ace1-type AChE gene was determined for the first time. The ace1 encoding a protein of 645 amino acids contained typical conserved motifs, such as FGESAG domains, catalytic triad, acyl pocket, oxyanino hole, choline binding site, peripheral anionic site, omega loop and conserved aromatic residues. R P. japonica displayed 50-times greater resistance to chlorpyrifos or mathamidophos with a significantly lower AChE sensitivity to paraoxon, malaoxon, chlorpyrifos or methamidophos than its S counterpart. Five amino acids in the ace1 of R P. japonica differed from those found in S P. japonica. One of them, F358S, located in the acyl-binding ...
Define acetylcholinesterase. acetylcholinesterase synonyms, acetylcholinesterase pronunciation, acetylcholinesterase translation, English dictionary definition of acetylcholinesterase. n. An enzyme in the blood and in certain tissues that catalyzes the hydrolysis of acetylcholine. n an enzyme in nerve cells that is responsible for the...
1PWD: Crystal structures of complexes between the R61 DD-peptidase and peptidoglycan-mimetic beta-lactams: a non-covalent complex with a
1PWC: Crystal structures of complexes between the R61 DD-peptidase and peptidoglycan-mimetic beta-lactams: a non-covalent complex with a
By analogy with the natural product chelerythrine, which has been identified as an inhibitor of both acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), we prepared a small series of 8-hydroxy-2,7-naphthyridin-2-ium salts. Spectroscopic analyses allowed us to elucidate the zwitterionic nature of 2,
Is it true that using the positive pressure or positive deplacement ports on PICC lines eliminates the need for Heparin flushes? Why is it necessary to use Heparin flushes with PICC lines having a negative pressure port. If the line isnt used for blood draws, why the need for heparin? Peripheral saline locks dont require heparin. The blood flow at the tip of the PICC is far greater than that of a peripheral site. Why Heparin?
Recombinant Acetylcholinesterase (AChE) Protein. Species: Mouse (Murine). Source: Escherichia coli (E. coli). Order product ABIN6301593.
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Optimization of an essentially inactive 3,4-dihydro-2H-pyrano[3,2-c]quinoline carboxylic ester derivative as acetylcholinesterase (AChE) peripheral anionic site (PAS)-binding motif by double O → NH bioisosteric replacement, combined with molecular hybridization with the AChE catalytic anionic site (CAS) inhibitor 6-chlorotacrine and molecular dynamics-driven optimization of the length of the linker has resulted in the development of the trimethylene-linked 1,2,3,4-tetrahydrobenzo[h][1,6] ...
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Acetylcholinesterase (AChE) exhibits functions unrelated to the catalysis of acetylcholine (ACh) in particular during development. Although the underlying mechanism(s) is presently unknown, a candidat
Lanks, K W.; Dorwin, J M.; and Papirmeister, B, "Increased rate of acetylcholinesterase synthesis in differentiating neuroblastoma cells." (1974). Subject Strain Bibliography 1974. 492 ...
Abstract: Environmental citrate or malonate is degraded by a range of aerobic or anaerobic bacteria. For chosen illustrations, the genes encoding the specific enzymes with the degradation pathway are explained along with the encoded proteins and their catalytic mechanisms. Aerobic micro organism degrade citrate quickly by The fundamental enzyme products in the cell if a selected transporter for citrate is offered. Anaerobic degradation of citrate in Klebsiella pneumoniae needs the so-termed substrate activation module to transform citrate into its thioester Together with the phosphoribosyl dephospho-CoA prosthetic group of citrate lyase. The citryl thioester is subsequently cleaved into oxaloacetate as well as acetyl thioester, from which a whole new citryl thioester is formed given that the turnover carries on. The degradation of malonate Also features a substrate activation module by using a phosphoribosyl dephospho-CoA prosthetic group. The equipment receives Prepared for turnover just after ...
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We are happy to share a great write-up by colorimeter user (and kickstarter backer) Steve Maxwell "Detecting Pesticides in Organic and Conventional Raspberries". Steve has used a modified colorimeter along with a acetylcholinesterase inhibition assay to determine whether there was any detectable difference in the levels of pesticides found in store-bought organic versus conventional raspberries.. The acetylcholinesterase (AChE) inhibition assay works as follows: Activity of AChE produces thiocholine which reacts with Ellmans Reagent (DNTB: 5,5-dithio-bis-[2-nitrobenzoic acid) to produce a 412nm absorbing product. The product is measured with a colorimeter or spectrophotometer at 412nm to determine AChE activity. Pesticides in food (mainly Carbamate and Organophosphate) inhibit AChE activity thereby also inhibiting the production of the 412nm product in the assay tube.. For this pesticide assay, Steve used a commercially available kit, the Rapid Pesticide Detection Test Kit from RenekaBio, Cat ...
Authors: MIROSLAV POHANKA, JANA ZDAROVA KARASOVA, KAMIL KUCA, JIRI PIKULA Abstract: Multichannel spectrophotometry was performed to assay for paraoxon in spiked beverages. A 96-well microplate was used for this purpose. The measuring protocol was based on inhibition of the enzyme acetylcholinesterase by paraoxon that resulted in decreased or no reaction of the enzyme product thiocholine with Ellmans reagent (5,5-dithiobis [2-nitrobenzoic acid]). The above assay was practically tested using spiked drinking water, mineral water, and coffee. Analytical parameters such as the limit of detection, time, and sample size consumption were adequate. The limit of detection for beverages ranged from 32 to 48 ppb corresponding to 0.32-0.48 ng of paraoxon in absolute values. The described assay seems to be convenient in terms of practical use. Keywords: Acetylcholinesterase, cholinesterase, biosensing, pesticides, assay, Ellman. Full Text: PDF ...
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Various types of acetylcholinesterase (AChE) subunits are characterized by specific C-terminal peptides. In Torpedoand mammals, alternative exons encode H peptides, which contain a C-terminal signal...
Molecular isoform distribution and glycosylation of acetylcholinesterase are altered in brain and cerebrospinal fluid of patients with Alzheimers disease
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We investigate the possibility of using acetylthiocholine iodide as pseudosubstrate for amperometric detection. Our ... is quantified by the oxidation of the thiocholine that is produced enzymatically by the hydrolysis of the acetylthiocholine ... investigation demonstrates that operational conditions for any amperometric biosensor that use acetylthiocholine iodide must be ... Keywords: acetylthiocholine iodide; acetylthiocholine chloride; amperometry; acetylcholinesterase acetylthiocholine iodide; ...
Acetylthiocholine chloride for your research needs. Find product specific information including CAS, MSDS, protocols and ...
... assessed as hydrolysis of acetylthiocholine iodide per mg of protein in hypothalamus administered qd for 7 days measured 1 hr ...
Inhibition of human erythrocyte acetylcholinesterase using acetylthiocholine chloride as substrate preincubated for 15 mins ...
... assessed as hydrolysis of acetylthiocholine iodide per mg of protein in hippocampus at 10 mg/kg, po qd for 7 days measured 1 hr ...
ACETYLTHIOCHOLINE. AT3 as a free ligand exists in 3 entries. Examples include: 2HA5 2C58 2C4H ...
Crystal structure of mutant S203A of acetylcholinesterase complexed with acetylthiocholine. Display Files *FASTA Sequence ...
acetylthiocholine. This is a preview of subscription content, log in to check access. ...
Keywords: acetylcholinesterase; organophosphorus compounds; pesticides; thiocholine; acetylthiocholine; nanomaterials ...
a) 198 mg acetylthiocholine chloride (10 mM). (b) bring to 100 ml with 0.05M phosphate buffer, pH 7.2 ...
Acetyl thiocholine iodide (ATCI), 5,5-dithiobis-2-nitrobenzoate ion (DTNB), trisfamino methane hydrochloride (Tris-HCl), bovine ...
In general, acetylthiocholine was hydrolysed slightly more rapidly by insect cholinesterases. A unique cholinesterase was found ... Kinetic data indicate that acetylthiocholine has a greater affinity than does phenyl thioacetate for a variety of enzyme ... The utility of histochemistry in conjunction with in vitro methods is discussed.The substrates acetylthiocholine and phenyl ... Ultrastructural evidence shows that cholinesterases that hydrolyse acetylthiocholine are membrane-bound. Phenyl thioacetate was ...
Prepare 1 mM acetylthiocholine iodide (ATCh: Mr 289.18 g/mol) in 4% glycerol, 25 mM Tris (pH 7.0) in a 1.5 ml microcentrifuge ... Acetylthiocholine iodide. Sigma-Alderich. 1480. Acetylcholinesterase from Electrophorus electricus (electric eel). Sigma- ...
Activity is expressed as nmol acetylthiocholine min−1 mg−1 protein.. The catalase (CAT) activity was determined by monitoring ... The principle of this method is the hydrolysis of acetylthiocholine iodide by AChE, and spectrophotometrical detection (410 nm ... Acetylcholinesterase (AChE) activity (nmol hydrolysed acetylthiocholine iodide*min−1*mg−1 protein), S-glutathione transferase ( ... of the yellow product of the reaction of acetylthiocholine with DTNB in adequate milieu. ...
Acetylthiocholine chloride A substrate for acetylcholinesterase 6050-81-3. sc-257066 sc-257066A 1 g. 5 g. $65.00 $245.00 0 ... Acetylthiocholine iodide A nAChR agonist and substrate of acetylcholinesterase 1866-15-5. sc-208323 sc-208323A sc-208323B sc- ...
... acetylthiocholine (ASCh; □), or choline (chol; ▴). Log EC50 values and Hill coefficients (± S.E.M.) are provided in Table 2, ... and perhaps acetylthiocholine; and very weak potency for choline (Fig. 7, Table 2). Lobeline (not shown) and succinylcholine ... 100 μM acetylthiocholine (75%) » 3.8 mM (estimated) choline (22% at 1 mM). Self-inhibitory IC50 values were also determined for ... 7.1 μM acetylthiocholine » 290 μM choline. Lobeline (IC50 = 76 nM) had ligand binding competition potency greater than any ...
... acetylthio)choline. J. Am. Chem. Soc. 2000, 122, 2981-2987. [Google Scholar] [CrossRef] ... Consider the acylation transition state for AChE catalyzed hydrolysis of acetylthiocholine (ATCh). By measuring β-deuterium ... A secondary isotope effect study of equine serum butyrylcholinesterase-catalyzed hydrolysis of acetylthiocholine. Chem. Biol. ... The reactant state for substrate-activated turnover of acetylthiocholine by butyrylcholinesterase is a tetrahedral intermediate ...
Kinetics and Mechanism of Hydrolysis of Acetylthiocholine by Butyrylcholine Esterase By: Karel Komers, Alexandr Čegan and Marek ...
Predicting the Behavior of the Interaction of Acetylthiocholine, pH and Temperature of an Acetylcholinesterase Sensor ...
The enzyme activity was finally expressed in μmol of acetylthiocholine hydrolyzed/min/mg tissue. ... acetylthiocholine (6.7 mg/mL). The absorbance change during 5 min intervals was measured at 405 nm immediately. The ...
A DNA sequence encoding the brain and muscle form of human AChE (AChE-T) was constructed in our laboratory from cloned cDNA and genomic sequences, and tentatively identified by its homology to known...
Current provided by oxidation of thiocholine previously created from acetylthiocholine by enzyme catalyzed reaction was in a ... Current provided by oxidation of thiocholine previously created from acetylthiocholine by enzyme catalyzed reaction was in a ... Measurements were started by immersing the biosensor into 1 mM acetylthiocholine chloride (ATChCl) in PBS. The concentration of ... activity measurement is typically based on electrochemical oxidation of nascent thiocholine coming from acetylthiocholine [20, ...
Acetylthiocholine iodide. Adenosine-5-triphosphoric acid, disodium salt. Allophanic acid amide; Carbamoylurea. ...
Activity: Measured by its ability to cleave acetylthiocholine; the specific activity is ,250nM/min./μg ...
  • Kinetic data indicate that acetylthiocholine has a greater affinity than does phenyl thioacetate for a variety of enzyme sources. (nih.gov)