Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.1.8 (cholinesterase)
12,691 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. It was recently proposed that acetylcholinesterase (AChE), in addition to its esteratic activity, has proteolytic activity such that it may cleave the beta-amyloid precursor (beta-APP) within the beta-amyloid sequence. The purpose of this paper was to examine further whether AChE or butyrylcholinesterase (BuChE) had associated proteinase activity that was involved in the metabolism of beta-APP. 2. The ability of various preparations of AChE and BuChE to hydrolyze two synthetic fragments of beta-APP695 as model substrates containing the normal and aberrant cleavage sites was studied. 3. Digestion of these synthetic substrates with commercial preparations of Electrophorus electricus AChE indicated the presence of a trypsin-like proteolytic activity cleaving each peptide at the carboxy-terminal side of an internal lysine residue. 4. Purification of the trypsin-like proteinase activity by aminobenzamidine affinity chromatography yielded a preparation that was devoid of AChE activity but retained all of the proteinase activity. 5. Amino-terminal sequence analysis of this preparation showed that the first 13 amino acid residues were identical to beta-pancreatic trypsin. 6. These data indicate that the proteinase activity found in these commercial preparations of AChE is due to contamination with trypsin.
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PMID:Proteolysis at the secretase and amyloidogenic cleavage sites of the beta-amyloid precursor protein by acetylcholinesterase and butyrylcholinesterase using model peptide substrates. 824 91

Acridine ligand affinity chromatography is an effective means of acetylcholinesterase (AChE) purification. However, the synthesis of these resins is laborious and expensive. We have developed an acridine ligand affinity resin that is easy to produce, inexpensive, and selective for AChE over butyrylcholinesterase. The resin is produced in a single synthetic step by attaching the aminoacridine tacrine to epoxy-activated Sepharose. AChE from bovine serum (59% yield), Torpedo electric organ (27-60% yield), and two commercial sources of eel AChE (> 92% yield) is purified using the affinity resin. One commercial source of eel AChE contains two proteins with molecular weights of 80 and 55 kDa upon purification, while two proteins with molecular weights of 55 and 25 kDa are isolated from the other commercial source, presumably representing degraded AChE. The degradation state of the commercially available eel AChE preparations did not influence their specific activities. The isolation of AChE from bovine serum results in a single 80-kDa protein. However, butyrylcholinesterase is not purified from the serum. Using the tacrine affinity resin, and 80-kDa AChE, solubilized from Torpedo electric organ membranes by protease digestion, can also be purified. Velocity sedimentation analysis of the Torpedo AChE reveals that the molecular forms isolated are either tetrameric or asymmetric when solubilized by collagenase or trypsin, respectively. Overall, the tacrine affinity resin which is simple and inexpensive to produce allows for the selective isolation of AChE from diverse biological matrices.
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PMID:Purification of acetylcholinesterase by tacrine affinity chromatography. 852 21

Serine esterases react with [3H]diisopropylphosphofluoridate ([3H]DFP) to produce radioactive adducts that can be resolved by denaturing slab gel electrophoresis. To identify an esterase or its catalytic subunit, a potential substrate was included in the reaction mixture with the expectation that it would suppress the enzyme's reaction with [3H]DFP. The nature of the enzyme could be inferred from the character of the substrates that suppress labeling. The validity of this analytical method was tested with two serine proteases, trypsin and alpha-chymotrypsin, and two serine esterases, acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE), and several of their natural or model substrates or inhibitors. Application of the method to complex biological systems was tested with chicken embryo brain microsomes. Trypsin labeling with [3H]DFP was suppressed by alpha-N-benzoyl-l-arginine ethyl ester (BAEE) and poly-l-lysine but not by benzoyl-l-tyrosine ethyl ester (BTEE). [3H]DFP labeling of chymotrypsin was suppressed by both BAEE and BTEE. Labeling of AChE and BuChE was suppressed by their natural and some related substrates and inhibitors. [3H]DFP reacted with brain microsomes to produce nine distinct radioactive bands. When the relevant substrates and inhibitors of AChE were included in the reaction mixtures, labeling of only the 95-kDa band was suppressed, implicating it as AChE. Labeling of the 85- and 79-kDa bands was inhibited by butyrylcholine, suggesting that these proteins have BuChE activity.
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PMID:Identification of serine esterases in tissue homogenates. 1003 48

Mouse plasma acetylcholinesterase (AChE) tetramers (G4) and dimers (G2) were retained by edrophonium-Sepharose, whereas AChE monomers (G1), and G4, G2 and G1 butyrylcholinesterase (BuChE) forms were not. Plasma G4 or G1 AChE did not differ in their affinity for edrophonium. G1 AChE, and G1 and G2 BuChE were retained in octyl-Sepharose, while G4 and G2 AChE, and G4 BuChE eluted freely. The amphiphilic behaviour of G1 AChE remained unmodified after incubation with trypsin. The electrophoretic mobility of the AChE monomers varied with the detergent added to the samples. The results show that mouse plasma G1 AChE possesses hydrophobic regions, which prevent its binding to the affinity matrix, and afford its interaction with octyl-Sepharose. The hydrophobic regions in G1 AChE probably provide conformational stability to disulfide-linked subunits in hydrophilic dimers.
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PMID:Amphiphilic properties of acetylcholinesterase monomers in mouse plasma. 1032 68

3-Alkylpyridinium polymers (poly-APS), composed of 29 or 99 N-butyl-3-butyl pyridinium units, were isolated from the marine sponge Reniera sarai. They act as potent cholinesterase inhibitors. The inhibition kinetics pattern reveals several successive phases ending in irreversible inhibition of the enzyme. To provide more information on mechanism of inhibition, interaction of poly-APS and N-butyl-3-butyl pyridinium iodide (NBPI) with soluble dimeric and monomeric insect acetylcholinesterase (AChE) was studied by using enzyme intrinsic fluorescence and light scattering, conformational probes ANS and trypsin, and SDS-PAGE. Poly-APS quenched tryptophan fluorescence emission of AChE more extensively than NBPI. Both inhibitors exhibited a pseudo-Lehrer type of quenching. Interaction of poly-APS with dimeric AChE did not induce significant changes of the enzyme conformation as assayed by using the hydrophobic probe ANS and trypsin digestion. In contrast to NBPI, titration of both monomeric and dimeric AChE with poly-APS resulted in the appearance of large complexes detected by measuring light scattering. An excess of poly-APS produced AChE precipitation as proved on SDS-PAGE. None of the effects were observed with trypsin as a control. It was concluded that AChE aggregation and precipitation rather than the enzyme conformational changes accounted for the observed irreversible component of poly-APS inhibition.
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PMID:Interaction of 3-alkylpyridinium polymers from the sea sponge Reniera sarai with insect acetylcholinesterase. 1039 43

Reactive phosphonate diesters were designed and prepared as inhibitors of serine proteases and esterases. Inactivation of trypsin, chymotrypsin, and butyrylcholinesterase was determined by residual enzymatic activity as well as by the release of a chromogenic or fluorogenic product of the inhibition reaction. Second-order rate constants were determined from rates of nitrophenol formation. Application of the reaction for active-site titration of enzyme preparations is demonstrated. A basic functional group present in the nitrophenyl tropane phosphonate diester was shown to confer selectivity for inactivation of trypsin and chymotrypsin. Biotinylated derivatives of the phosphonate diesters were prepared to permit analysis of proteins modified in the inhibition reaction. Labeled polypeptides were resolved by SDS-PAGE, electroblotted, and detected by streptavidin-peroxidase staining. A detection limit of less than 4 ng, corresponding to 20 nM of trypsin, was demonstrated. Pretreatment of enzymes with DFP or nonbiotinylated phosphonates specifically blocks the labeling. This technique permits identification of serine proteases in complex mixtures with good sensitivity and specificity.
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PMID:Inhibition and labeling of enzymes and abzymes by phosphonate diesters. 1082 63

Various proteins/enzymes obtained commercially were tested for the presence of endogenously nitrated tyrosine by Western blot analysis omitting reducing agent in the step of SDS-PAGE. Histones II-S and VIII-S, IgG, cAMP-dependent protein kinase (PKA), phosphorylase b, and phosphorylase kinase exhibited strong immunoreactive bands. Histone VI-S, glycogen synthase, lactate dehydrogenase, actin, thyroglobulin, and macroglobulin exhibited moderate immunoreactivity. Histone III-S, casein, acetyl cholinesterase, DNase I, and lipase had only traceable immunoreactivity. Whereas histone VII-S, pyruvate kinase, trypsin, pepsin, chymotrypsin, protease IV, and protease XIII, and glutathione S-transferase lacked immunoreactivity. A variation of immunoreactivity between hypertensive and normaltensive rat hearts was found in the histone-agarose fractions of crude extracts. Additionally, nitrotyrosine immunoreactivity was observed in non-mammalian organisms including Eschericia coli, Saccharomyces cerevisiae and Triticum vulgaris. Upon the treatment of 15 microM peroxynitrite (PN), strong oxidant derived from nitric oxide (NO), the apparent Km of PKA for cAMP increased from approximately 10(-8) to 10(-6) M. The results imply that the varied nitration of tyrosine residues in proteins/enzymes may occur as a post-translational modification in vivo, and such discriminative nitration may be vital in PN/NO-regulated signal transduction cascade.
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PMID:Protein nitration. 1119 83

1. Acetylcholinesterase (AChE, EC 3.1.1.7) and butyrylcholinesterase (BuChE, EC 3.1.1.8) are enzymes that catalyze the hydrolysis of esters of choline. 2. Both AChE and BuChE have been shown to copurify with peptidases. 3. BuChE has also been shown to copurify with other proteins such as transferrin, with which it forms a stable complex. In addition, BuChE is found in association with beta-amyloid protein in Alzheimer brain tissues. 4. Since BuChE copurifies with peptidases, we hypothesized that BuChE interacts with these enzymes and that this association had an influence on their catalytic activities. One of the peptidases that copurifies with cholinesterases has specificity similar to trypsin, hence, this enzyme was used as a model to test this hypothesis. 5. Purified BuChE causes a concentration-dependent enhancement of the catalytic activity of trypsin while trypsin does not influence the catalytic activity of BuChE. 6. We suggest that, in addition to its esterase activity, BuChE may assume a regulatory role by interacting with other proteins.
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PMID:Butyrylcholinesterase-Mediated enhancement of the enzymatic activity of trypsin. 1156 38

Previous kinetic studies found that butyrylcholinesterase (BChE) inhibited by (1R)-isomalathions readily reactivated, while enzyme inactivated by (1S)-isomers did not. This study tested the hypothesis that (1R)- and (1S)-isomers inhibit BChE by different mechanisms, yielding distinct adducts identifiable by peptide mass mapping with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Equine BChE (EBChE) was inhibited to <10% of control activity with each isomer of isomalathion and the reference compound isoparathion methyl. Control and treated enzyme was digested with trypsin, and peptides were fractionated with HPLC. Separated and unseparated peptides were analyzed with MALDI-TOF-MS. Identity of an organophosphorus peptide adduct was confirmed by fragmentation using postsource decay analysis. EBChE inhibited by (1R)-isomalathions or (S)-isoparathion methyl readily reactivated after oxime treatment with 30-40% activity recovered. Enzyme inactivated by (1S)-isomalathions or (R)-isoparathion methyl recovered <2% and <5% activity, respectively, after oxime treatment. MALDI-TOF-MS analysis revealed that inhibition of EBChE by (1R)-isomalathions and (R)- or (S)-isoparathion methyl yielded O,S-dimethyl phosphate adducts. Enzyme inactivated by (1S)-isomalathions produced only O-methyl phosphate adduct. EBChE modified by (1R)-isomalathions or either enantiomer of isoparathion methyl yielded an O-methyl phosphate adduct as well. The results indicate that EBChE inhibition by (1R)-isomalathions proceeds with loss of diethyl thiosuccinate, but inactivation by (1S)-isomers occurs with loss of thiomethyl as the primary leaving group followed by rapid expulsion of diethyl thiosuccinate to yield an aged enzyme. Furthermore, the data suggest that aging of the O,S-dimethyl phosphate adduct occurs via an S(N)2 process with loss of thiomethyl.
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PMID:Identification of butyrylcholinesterase adducts after inhibition with isomalathion using mass spectrometry: difference in mechanism between (1R)- and (1S)-stereoisomers. 1160 83

The classical laboratory tests for exposure to organophosphorus toxicants (OP) are inhibition of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activity in blood. In a search for new biomarkers of OP exposure, we treated mice with a biotinylated organophosphorus agent, FP-biotin. The biotinylated proteins in muscle were purified by binding to avidin-Sepharose, separated by gel electrophoresis, digested with trypsin, and identified from their fragmentation patterns on a quadrupole time-of-flight mass spectrometer. Albumin and ES1 carboxylesterase (EC 3.1.1.1) were found to be major targets of FP-biotin. These FP-biotinylated proteins were also identified in mouse plasma by comparing band patterns on nondenaturing gels stained for albumin and carboxylesterase activity, with band patterns on blots hybridized with Streptavidin Alexa-680. Two additional FP-biotin targets, AChE (EC 3.1.1.7) and BChE (EC 3.1.1.8), were identified in mouse plasma by finding that enzyme activity was inhibited 50-80%. Mouse plasma contained eight additional FP-biotinylated bands whose identity has not yet been determined. In vitro experiments with human plasma showed that chlorpyrifos oxon, echothiophate, malaoxon, paraoxon, methyl paraoxon, diazoxon, diisopropylfluorophosphate, and dichlorvos competed with FP-biotin for binding to human albumin. Though experiments with purified albumin have previously shown that albumin covalently binds OP, this is the first report of OP binding to albumin in a living animal. Carboxylesterase is not a biomarker in man because humans have no carboxylesterase in blood. It is concluded that OP bound to albumin could serve as a new biomarker of OP exposure in man.
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PMID:Albumin, a new biomarker of organophosphorus toxicant exposure, identified by mass spectrometry. 1552 94


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