Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.1.7 (acetylcholinesterase)
 28,390 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

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.
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PMID:Determinants of substrate specificity of a second non-neuronal secreted acetylcholinesterase from the parasitic nematode Nippostrongylus brasiliensis. 1075 51

It has been reported that the ACTH-(4-9) analog H-Met(O(2))-Glu-His-Phe-D-Lys-Phe-OH (ORG 2766) administered in adulthood has trophic effects on neuronal tissue and when given postnatally, it can induce long-lasting changes in brain development. In the present study, we investigated whether early postnatal treatment with ORG 2766 affects adult neuronal vulnerability, i.e. the sensitivity of cholinergic neurons against excitotoxic damage. Wistar rat pups received injections of ORG 2766 or saline on postnatal days 1, 3 and 5 and were then left undisturbed until adulthood. At the age of 6 months, the animals were subjected to unilateral lesion of magnocellular basal nucleus by infusion of high dose of N-methyl-D-aspartate (NMDA). The effects of the excitotoxic insult were studied 28 hours and 12 days after the lesion by measuring both the acute cholinergic and glial responses, and the final outcome of the degeneration process. Twenty eight hours after NMDA infusion, postnatally ACTH-(4-9)-treated animals showed stronger suppression of choline-acetyltransferase immunoreactivity and increased reaction of glial fibrillary acidic protein -immunopositive astrocytes in the lesioned nucleus compared to control animals. However, 12 days post-surgery, the NMDA-induced loss of cholinergic neurons, as well as the decrease of their acetylcholinesterase -positive fibre projections in the cortex, were less in ACTH-(4-9) animals. Our data indicate that the early developmental effects of ACTH-(4-9) influence intrinsic neuroprotective mechanisms and reactivity of neuronal and glial cells, thereby resulting in a facilitated rescuing mechanism following excitotoxic injury.
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PMID:Postnatal treatment with ACTH-(4-9) analog ORG 2766 attenuates N-methyl-D-aspartate-induced excitotoxicity in rat nucleus basalis in adulthood. 1103 12

The motility of the avian oviduct is controlled by hormones and neurons, but little is microscopically known about a neural network in the oviduct. The present study was investigated to determine the distribution of nitric oxide-synthesizing neurons in the oviduct of the pigeon by histochemistry for nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d). The NADPH-d reaction was seen in the neurons and fibers. NADPH-d neurons were mainly distributed around the arterioles of the intermuscular tissue in the upper oviduct (infundibulum, magnum, and isthmus); in addition, NADPH-d neurons were also seen in the smooth muscle layers and lamina propria in the lower oviduct (uterus and vagina). NADPH-d neurons were found singly or in small groups of two-eight cell bodies. The number of NADPH-d neurons was smallest in the infundibulum, gradually increased toward the vagina. NADPH-d was also shown to be strongly positive in many neurons in the ganglia of the vaginal adventitia. Bundles of NADPH-d fibers ran in the smooth muscle layer, surrounded blood vessels, or connected with small groups of NADPH-d neurons by forming strands. Thin fibers branched from these bundles and constituted a finer network in the smooth muscle layer and lamina propria. Acetylcholinesterase staining in neurons and fibers showed a similar pattern of NADPH-d distribution in the oviduct. By double staining, 70 approximately 77% of neurons showed colocalization of NADPH-d and acetylcholinesterase in the uterus and vagina. Tyrosine hydroxylase immunoreactivity stained only nerve fibers and were distributed largely around blood vessels in the oviduct. Nerve fibers immunoreactive for calcitonin-gene related peptide, galanin, methionine-enkephalin, substance P, or vasoactive intestinal peptide were found sparsely in the oviduct. These results demonstrate that nitrergic neurons make up a large subpopulation of intrinsic neurons that are closely associated with a cholinergic system in the pigeon oviduct, thus suggesting that nitric oxide and acetylcholine could be used to modify the relaxation of the avian oviduct.
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PMID:Innervation of the pigeon oviduct: correlation of NADPH diaphorase with acetylcholinesterase, tyrosine hydroxylase, and neuropeptides. 1110 84

The motility of the avian cloaca is under neural control, but little is known about the neural network that accomplishes this function. This present study was designed to determine the distribution of nitric oxide-synthesising neurons in the pigeon cloaca by enzyme histochemistry for reduced nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d). NADPH-d-positive staining was seen in the neurons and fibres in the cloaca. The highest density of nerve fibres was noted in the coprodeum and the lowest in the proctodeum. In the coprodeum, NADPH-d neurons were found singly, formed small groups of 2-10 neurons, or were seen in plexuses in the muscle layer, lamina propria, or around the arterioles. Several NADPH-d-positive neurons were also observed in the ganglia of the cloaca. NADPH-d fibres ran in the muscle layer, lamina muscularis mucosae and lamina propria, or surrounded blood vessels. The distribution pattern of acetylcholinesterase (AChE)-stained neurons and fibres in the cloaca was similar to that of NADPH-d. Double staining for NADPH-d and AChE showed colocalisation of the 2 enzymes in many neurons of the cloaca. Tyrosine hydroxylase (TH)-immunoreactive nerve fibres originating outside the cloaca were also noted. In the urodeum and proctodeum, neurons or fibres positive for NADPH-d, AChE or TH were scattered in the lamina propria. Nerve fibres immunoreactive for calcitonin-gene related peptide, galanin, methionine-enkephalin, substance P, and vasoactive intestinal peptide were found sparsely in the cloaca. Our results demonstrate that nitrergic neurons constitute a subpopulation which is closely associated with the cholinergic system in the pigeon cloaca.
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PMID:Innervation of NADPH diaphorase-containing neurons correlated with acetylcholinesterase, tyrosine hydroxylase, and neuropeptides in the pigeon cloaca. 1127 43

Thyroglobulin (Tg) binds to cell surfaces through various binding sites of high, moderate and low affinity. We have previously shown that binding with low to moderate affinity is pH dependent, selective, but not tissue specific. To identify the regions of Tg involved in this cell surface binding, we studied the binding of (125)I-labeled cyanogen bromide peptides from human Tg to cell surfaces of thyroid cells (inside-out follicles) and of CHO cells. Electrophoretic analysis of cell homogenates after binding of native or of reduced and alkylated (125)I-labeled peptides showed that three peptides, P1, P2 and P3, were always associated with the cells. Sequence analysis allowed the identification of P1 (Ser-2445 to Met-2596 or Met-2610) and P2 (Phe-2156 to Met-2306). P3 proved to be a mixture of several peptides among which two were identified: P3-1 (Cys-1306 to Met-1640) and P3-2 (Cys-2035 to Met-2413) which includes P2. P1, P2 and P3-2 are entirely (P1) or partly (P2 and P3-2) located in the C-terminal domain of Tg homologous with acetylcholinesterase. The smallest peptides, P1 and P2, were purified by preparative electrophoresis. They both displayed strong binding properties towards cell surfaces. Inhibition experiments of (125)I-labeled Tg binding by P1 or P2 indicated that they were involved in Tg binding to cell surfaces. All the other peptides tested for their binding abilities were either not or only poorly involved in Tg binding to cell surfaces, which suggested that P1 and P2 are major Tg sites of binding to cell surfaces. These two peptides are not involved in the binding of Tg to the known Tg 'receptors' described in the literature, to which recycling, transcytosis and regulation functions have been ascribed. Thus they are potential tools to identify cell surface components involved in the process of Tg endocytosis leading to lysosomal degradation.
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PMID:Identification of thyroglobulin domain(s) involved in cell-surface binding and endocytosis. 1143 Nov 54

The nature of the dynamical coupling between a protein and its surrounding solvent is an important, yet open issue. Here we used temperature-dependent protein crystallography to study structural alterations that arise in the enzyme acetylcholinesterase upon X-ray irradiation at two temperatures: below and above the glass transition of the crystal solvent. A buried disulfide bond, a buried cysteine, and solvent exposed methionine residues show drastically increased radiation damage at 155 K, in comparison to 100 K. Additionally, the irradiation-induced unit cell volume increase is linear at 100 K, but not at 155 K, which is attributed to the increased solvent mobility at 155 K. Most importantly, we observed conformational changes in the catalytic triad at the active site at 155 K but not at 100 K. These changes lead to an inactive catalytic triad conformation and represent, therefore, the observation of radiation-inactivation of an enzyme at the atomic level. Our results show that at 155 K, the protein has acquired--at least locally--sufficient conformational flexibility to adapt to irradiation-induced alterations in the conformational energy landscape. The increased protein flexibility may be a direct consequence of the solvent glass transition, which expresses as dynamical changes in the enzyme's environment. Our results reveal the importance of protein and solvent dynamics in specific radiation damage to biological macromolecules, which in turn can serve as a tool to study protein flexibility and its relation to changes in a protein's environment.
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PMID:Specific protein dynamics near the solvent glass transition assayed by radiation-induced structural changes. 1156 86

Hodological, electrophysiological, and ablation studies indicate a role for the basal forebrain in telencephalic vocal control; however, to date the organization of the basal forebrain has not been extensively studied in any nonmammal or nonhuman vocal learning species. To this end the chemical anatomy of the avian basal forebrain was investigated in a vocal learning parrot, the budgerigar (Melopsittacus undulatus). Immunological and histological stains, including choline acetyltransferase, acetylcholinesterase, tyrosine hydroxylase, dopamine and cAMP-regulated phosphoprotein (DARPP)-32, the calcium binding proteins calbindin D-28k and parvalbumin, calcitonin gene-related peptide, iron, substance P, methionine enkephalin, nicotinamide adenine dinucleotide phosphotase diaphorase, and arginine vasotocin were used in the present study. We conclude that the ventral paleostriatum (cf. Kitt and Brauth [1981] Neuroscience 6:1551-1566) and adjacent archistriatal regions can be subdivided into several distinct subareas that are chemically comparable to mammalian basal forebrain structures. The nucleus accumbens is histochemically separable into core and shell regions. The nucleus taeniae (TN) is theorized to be homologous to the medial amygdaloid nucleus. The archistriatum pars ventrolateralis (Avl; comparable to the pigeon archistriatum pars dorsalis) is theorized to be a possible homologue of the central amygdaloid nucleus. The TN and Avl are histochemically continuous with the medial aspects of the bed nucleus of the stria terminalis and the ventromedial striatum, forming an avian analogue of the extended amygdala. The apparent counterpart in budgerigars of the mammalian nucleus basalis of Meynert consists of a field of cholinergic neurons spanning the basal forebrain. The budgerigar septal region is theorized to be homologous as a field to the mammalian septum. Our results are discussed with regard to both the evolution of the basal forebrain and its role in vocal learning processes.
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PMID:Organization of the avian basal forebrain: chemical anatomy in the parrot (Melopsittacus undulatus). 1245 5

Insect acetylcholinesterase (AChE) is known to be a primary target of organophosphorus and carbamate insecticides. However chronic exposure to these chemicals has led to resistance to applied insecticides, due usually to mutation of the AChE gene. Analysis of the AChE gene (hm) of Musca domestica (the housefly), which is cloned in this report, reveals the relationship between mutation and insecticide resistance. The 2,076 bp hm encodes a mature protein of 612 amino acids (67 kDa), and an 80 residue signal peptide. Unlike the enzyme of 'sensitive' strains, the AChE used in this study was resistant to the organophosphorus insecticide, trichlorphon. DNA sequencing showed that this AChE is identical to that of the sensitive strains with the exception of three amino acids Met-82, Ala-262, and Tyr-327. Site-directed mutagenesis of the Ala-262 and Tyr-327 residues largely restored sensitivity to the insecticide, suggesting that these two residues are the key structural elements controlling sensitivity. In addition to these residues, Glu-234 and Ala-236 in the conserved sequence FGESAG are thought to play a role in modulating sensitivity to organophosphorus insecticides.
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PMID:Cloning, mutagenesis, and expression of the acetylcholinesterase gene from a strain of Musca domestica; the change from a drug-resistant to a sensitive enzyme. 1280 84

In the present work we investigated the in vitro effects of homocysteine (Hcy) and methionine (Met), metabolites accumulated in homocystinuria, on butyrylcholinesterase (BuChE) activity in rat serum. We also studied the kinetics of the inhibition of BuChE activity caused by Hcy. For determination of BuChE we used serum of 60-day-old Wistar rats, which was incubated in the absence (control) or presence of Hcy (0.01-0.5 mM) or Met (0.2-2.0 mM). The kinetics of the interaction of Hcy and BuChE was determined using the Lineweaver-Burk double reciprocal plot. Results showed that serum BuChE activity was not altered by Met, but it was significantly inhibited (37%) by 500 microM Hcy, a concentration similar to those found in blood of homocystinuric patients. The apparent Km values, in the absence and presence of 500 microM of Hcy, were 0.034 and 0.142 mM, respectively, and V(max) of BuChE for acetylcholine (ACh) as substrate was 1.25 micromol ACSCh/h/mg of protein. The Ki value obtained was 120 microM, and the inhibition was of the competitive type, suggesting a common binding site for Hcy and ACh. It is proposed that inhibition of cholinesterase activity may be one of the mechanisms involved in the neurological dysfunction observed in homocystinuria.
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PMID:Homocysteine inhibits butyrylcholinesterase activity in rat serum. 1456 69

Previously it has been demonstrated that the human epidermis synthesises and degrades acetylcholine and expresses both muscarinic and nicotinic receptors. These cholinergic systems have been implicated in the development of the epidermal calcium gradient and differentiation in normal healthy skin. In vitiligo severe oxidative stress occurs in the epidermis of these patients with accumulation of H2O2 in the 10(-3)M range together with a decrease in catalase expression/activity due to deactivation of the enzyme active site. It was also shown that the entire recycling of the essential cofactor (6R)-l-erythro-5,6,7,8-tetrahydrobiopterin via pterin-4a-carbinolamine dehydratase (PCD) and dihydropteridine reductase (DHPR) is affected by H2O2 oxidation of Trp/Met residues in the enzyme structure leading to deactivation of these proteins. Using fluorescence immunohistochemistry we now show that epidermal H2O2 in vitiligo patients yields also almost absent epidermal acetylcholinesterase (AchE). A kinetic analysis using pure recombinant human AchE revealed that low concentrations of H2O2 (10(-6)M) activate this enzyme by increasing the Vmax>2-fold, meanwhile high concentrations of H2O2 (10(-3)M) inhibit the enzyme with a significant decrease in Vmax. This result was confirmed by fluorescence excitation spectroscopy following the Trp fluorescence at lambdamax 280nm. Molecular modelling based on the established 3D structure of human AchE supported that H2O2-mediated oxidation of Trp(432), Trp(435), and Met(436) moves and disorients the active site His(440) of the enzyme, leading to deactivation of the protein. To our knowledge these results identified for the first time H2O2 regulation of AchE. Moreover, it was shown that H2O2-mediated oxidation of AchE contributes significantly to the well-established oxidative stress in vitiligo.
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PMID:Activation/deactivation of acetylcholinesterase by H2O2: more evidence for oxidative stress in vitiligo. 1476 37


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