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)

Electric organs of skate (Raja species) dissociate to form populations of individual electrocytes when incubated in saline solutions containing collagenase. The rate of dissociation was highly temperature dependent, with an apparent Q10 of > 6 in the range of 6 degrees-26 degrees C. The number of electrocytes per organ was relatively constant and independent of electric organ size, whereas mean cell diameters increased with organ size. The activities of two cholinergic marker enzymes, choline acetyltransferase (ChAT) and acetylcholinesterase (AChE), in extracts of whole fresh organs were much less than those reported for the electric ray Torpedo, suggesting a lower volume of terminals in the organ. Electrocytes prepared from collagenase-treated organs had good resting potentials and generated postsynaptic evoked potentials. Spontaneous and electrode pressure-evoked miniature endplate potentials (MEPPs) were readily recorded from isolated electrocytes. Incubation periods of more than 4 days in collagenase at 6 degrees C produced electrocytes with good resting potentials and very low MEPP frequencies, indicating denervation. Detachment of terminals and decreased MEPP frequencies were concurrent. The time course of denervation was followed with the appearance of ChAT and AChE activities in a small particulate fraction derived from washed electrocytes. Peak activities of both enzymes were seen at 4 days of incubation at 16 degrees C, but after 20 h at 16 degrees C. Electrocytes from 4-day, 6 degrees C incubations showed detached, mitochondria-rich nerve terminals and dissociated Schwann cells. In unfixed preparations examined with Nomarski optics, isolated nerve terminals were recognized and distinguished from nucleated Schwann cells. Electron micrographs show that isolated terminals were similar to attached terminals just before they dissociated. The MEPP frequencies and evoked potentials were normal at terminals just before dissociation. We conclude that the transmitter release process was normal in detached terminals and in terminals free of Schwann cells.
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PMID:Detached, purified nerve terminals from skate electric organ for biochemical and physiological studies. 885 32

To obtain information about the evolution of the cholinesterases, we investigated the cholinesterase activity of an agnathan vertebrate, the hagfish Myxine glutinosa. On the basis of evidence from enzymology, pharmacology, and molecular biology, we conclude that the cholinesterase activity is due to acetylcholinesterase (AChE). The enzyme hydrolyzes acetylthiocholine preferentially and exhibits substrate inhibition. The hydrolysis of both acetylthiocholine and butyrylthiocholine are inhibited in parallel by cholinesterase inhibitors, with the AChE-specific drug BW284c51 being the most potent; however, this drug and propidium, a peripheral anionic site ligand, are much weaker inhibitors of the hagfish enzyme than of Torpedo AChE. We used sequential extraction, collagenase digestion, and velocity sedimentation on sucrose gradients to determine that the AChE from the skeletal muscle of the hagfish is present in both globular and asymmetric forms. We also used the polymerase chain reaction with degenerate oligonucleotide probes and genomic DNA to obtain a 1 kb gene fragment for hagfish AChE. The enzyme has an acyl binding site typical of other vertebrate AChE, but lacks two aromatic residues implicated in the function of the peripheral anionic subsite. We discuss the relevance of our findings to the evolution of the cholinesterases in the vertebrates.
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PMID:Biochemical and molecular characterization of acetylcholinesterase from the hagfish Myxine glutinosa. 889 35

The distribution and glycosylation of acetylcholinesterase (AChE) forms in vesicles derived from sarcoplasmic reticulum of normal muscle (NMV) were investigated and compared with those from dystrophic muscle vesicles (DMV). AChE activity was similar in NMV and DMV. Most of the AChE in NMV and half in DMV were released with Triton X-100. Asymmetric (A12) and globular hydrophilic and amphiphilic (G4H, G4A, G2A, and G1A) AChE species occurred in NMV and DMV, the lighter forms being predominant. The percentage of G4H and G4A decreased in DMV. A fraction of the AChE that could not be extracted with detergent was detached with collagenase. Most of the detergent-released A12 AChE from NMV and nearly half in DMV failed to bind to Ricinus communis agglutinin (RCA-I). Conversely, the collagenase-detached isoforms bound to RCA, revealing that asymmetric AChE associated with internal membranes or basal lamina differed in glycosylation. Moreover, nearly half of G4A AChE in DMV and a few in NMV bound to RCA. Most of the RCA-unreactive G4A forms in NMV come from sarcolemma. The results indicate that dystrophy induces minor changes in the distribution and glycosylation of AChE forms in internal membranes of muscle.
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PMID:Glycosylation of acetylcholinesterase forms in microsomal membranes from normal and dystrophic Lama2dy mouse muscle. 934 41

Asymmetric acetylcholinesterase (AChE) is anchored to the basal lamina (BL) of cholinergic synapses via its collagenic tail, yet the complement of matrix receptors involved in its attachment remains unknown. The development of a novel overlay technique has allowed us to identify two Torpedo BL components that bind asymmetric AChE: a polypeptide of approximately 140 kDa and a doublet of 195-215 kDa. These were found to stain metachromatically with Coomassie blue R-250, were solubilized by acetic acid, and were sensitive to collagenase treatment. Upon sequence analysis, the 140 kDa polypeptide yielded a characteristic collagenous motif. Another AChE-binding BL constituent, identified by overlay, corresponded to a heparan sulfate proteoglycan. Lastly, we established that this proteoglycan, but not the collagenous proteins, interacted with at least one heparin binding domain of the collagenic tail of AChE. Our results indicate that at least two BL receptors are likely to exist for asymmetric AChE in Torpedo electric organ.
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PMID:At least two receptors of asymmetric acetylcholinesterase are present at the synaptic basal lamina of Torpedo electric organ. 975 26

A component of collagen-tailed acetylcholinesterase (asymmetric; A-AChE) in muscle forms a metabolically-stable pool which can be released from the cell surface only by collagenase, suggesting that part of the enzyme is covalently bound by its tail (COLQ) subunits. We have investigated whether this insoluble pool forms through covalent cross-linking of A-AChE to extracellular matrix glycoproteins by tissue transglutaminase (Tg; type 2 transglutaminase). Tg catalyzed the incorporation of the polyamine substrate 3[H]-putrescine into the collagen tail of affinity-purified avian A12-AChE. Complexes between A12-AChE and cellular fibronectin were also formed in vitro by Tg. In quail myotubes, retinoic acid, which stimulates the formation of epsilon(gamma-glutamyl)lysine isodipeptide bonds by Tg in myotubes, increased the proportion of extraction-resistant (er) A-AChE. Following irreversible inactivation of AChE by diisopropylfluorophosphate, entry of newly-synthesized A-AChE into the extraction-resistant pool was inhibited by a competitive Tg inactivator RS48373-007. The quantity of exogenously-added A 12 AChE incorporated into the extraction-resistant pool in living myotubes was increased by Tg in the presence of calcium. The inhibition of cross-bridge formation in fibrillar collagen by beta-aminopropionitrile, and pre-exposure of myotubes to a monoclonal antibody to fibronectin, resulted in a reduction in the size of the erA-AChE pool present on the cell-surface. The evidence supports the hypothesis that a component of insoluble collagen-tailed AChE, once subject to clustering influences mediated via reversible docking to proteoglycans and their receptors, is anchored at the cell surface through covalent cross-linking by Tg. The high stability of the epsilon(gamma-glutamyl)lysine isopeptide bond is likely to contribute to the observed low turnover of the erA-AChE fraction.
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PMID:Stabilization of collagen-tailed acetylcholinesterase in muscle cells through extracellular anchorage by transglutaminase-catalyzed cross-linking. 1071 26

One of the major problems in computational drug design is incorporation of the intrinsic flexibility of protein binding sites. This is particularly crucial in ligand binding events, when induced fit can lead to protein structure rearrangements. As a consequence of the huge conformational space available to protein structures, receptor flexibility is rarely considered in ligand design procedures. In this work, we present an algorithm for integrating protein binding-site flexibility into de novo ligand design and docking processes. The approach allows dynamic rearrangement of amino acid side chains during the docking and design simulations. The impact of protein conformational flexibility is investigated in the docking of highly active inhibitors in the binding sites of acetylcholinesterase and human collagenase (matrix metalloproteinase-1) and in the design of ligands in the S1' pocket of MMP-1. The results of corresponding simulations for both rigid and flexible binding sites are compared in order to gauge the influence of receptor flexibility in drug discovery protocols.
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PMID:Receptor flexibility in de novo ligand design and docking. 1622 Sep 75

Attempts were made to solubilize acetylcholinesterase from Wistar rat brains by extraction with dilute buffer, Triton X-100 and proteolytic digestion. About 13% of the total enzyme activity could be solubilized with 30 mM sodium phosphate buffer (pH 7) and the remainder brought into solution with 1% w/v Triton X-100. Storage of the brains in dry toluene for 3-6 months followed by extraction did not improve the yield and resulted in the loss of about half of the enzyme activity. Digestion with trypsin or collagenase was totally ineffective in solubilizing the enzyme from fresh or toluene-stored brains. The enzyme in the buffer and detergent extracts of fresh and toluene-stored brains was very stable when stored at -20 degrees C for several months although some activity was found in a 100,000 g pellet obtained by centrifugation of the thawed extracts. All enzyme preparations showed inhibition by excess substrate and an optimum substrate concentration of 2 mM acetylcholine. The Km of the crude tissue suspension was 80 microM acetylcholine while that of the buffer-soluble enzyme was 91 microM and that of the detergent-solubilized enzyme was 250 microM. Storage of the brains in toluene had little effect on these values. Starch-block electrophoresis and polyacrylamide gel electrophoresis showed up to five bands with different net charge while gradient gel electrophoresis revealed up to eleven forms with molecular weights ranging from 39,000 to 450,000. The electrophoretic pattern obtained depended on the preparation and extraction of the tissue as well as the temperature and the presence of salt, mercaptoethanol and inhibitors. Storage of the tissue in toluene does affect the yield and the properties of acetylcholinesterase obtained from rat brain thus emphasising the need to clearly define the methods and conditions of solubilization when reporting the presence of multiple molecular forms of acetylcholinesterase.
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PMID:The effect of solubilization on the properties and molecular forms of rat brain acetylcholinesterase. 1964 67

To obtain more information about the evolution of acetylcholinesterase in the vertebrates, we studied the cholinesterase activity from the brain of the lamprey Petromyzon marinus. We found that the enzyme is true acetylcholinesterase and that 98% of it is present in the G(4) globular form. Only 1% of the enzyme was found distributed among the asymmetric forms A(4), A(8) and A(12); an additional 1% of the activity could not be extracted from the brain. The identity of the asymmetric forms was confirmed by collagenase digestion. These data demonstrate that asymmetric acetylcholinesterase is present in the CNS of organisms representing all classes of vertebrates. However, our results are inconsistent with an evolutionary trend that has been observed for vertebrate brain acetylcholinesterase.
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PMID:Lamprey brain contains globular and asymmetric forms of acetylcholinesterase. 2050 Dec 14

Tailed acetylcholinesterase (AChE) was studied in three subcellular membrane fractions of mouse skeletal muscle: a fraction enriched in isolated motor endplates (C), an extrasynaptic membrane fraction (A) and a microsomal fraction (S). In the (C) fraction, tailed asymmetric 16S AChE required high salt conditions to be extracted, while in (A) and (S) microsomal membranes, a collagenase sensitive 16S form, was extracted by detergent alone. This apparent "hydrophobic" property suggests that there is a pool of 16S AChE which is probably bound to lipidic membranes. The detergent extractable (DE) 16S AChE was not concentrated in motor endplate-rich regions and differential inhibition of external and internal AChE demonstrated that it could have both intra- and extracellular locations in the adult differentiated muscle fibres.
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PMID:Association of tailed acetylcholinesterase to lipidic membranes in mammalian skeletal muscle. 2050 Dec 92

This study evaluated the effects of two exogenous enzymes on the resin-dentin interface. Collagenase (Col) and acetylcholinesterase (Ach) were used to simulate salivary enzymes and accelerate the aging process of the bonding interfaces. Four adhesives, Adper Single Bond 2 (SB), Clearfil SE Bond (SE), Clearfil tri-S Bond (S3) and G-Bond (G), were bonded to the dentin surfaces. After storage in water with collagenase or acetylcholinesterase, the specimens were examined using a microtensile bond strength test (MTBS). Nanoleakage patterns were observed with a scanning electron microscope (SEM). The MTBS results demonstrated significantly lower bond strengths in the groups stored with either enzyme than in water. SB exhibited severe degradation after exposure to collagenase, while G showed severe degradation after exposure to acetylcholinesterase. All of the self-etch systems (SE, S3 and G) exhibited water-tree patterns within the adhesive layer when immersed in water for three months. The etch-and-rinse system (SB) showed nanoleakage within the hybrid layer and the adhesive.
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PMID:Biodegradation of all-in-one self-etch adhesive systems at the resin-dentin interface. 2212 5


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