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:3.4.24.3 (collagenase)
18,340 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The kinetics of AChE solubilization from intact motor endplates of mouse diaphragm, by collagenase, papain and hyaluronidase, was studied in parallel with the ultrastructural localization of AChE in treated neuromuscular junctions. Hyaluronidase did not solubilize more AChE from isolated motor endplate regions than Ringer's solution itself. Residual AChE activity could be demonstrated histochemically in motor endplates even after the plateau of solubilization by collagenase or papain was reached. Less than 35% of junctional AChE is left after collagenase, and less than 20% after papain treatment, as estimated by the percentage of AChE activity left in the isolated endplate region of the diaphragm after protease treatment. Cytochemically, both proteases had a similar effect on postsynaptic AChE. Residual AChE activity was distributed randomly, adhering to the sarcolemma of junctional clefts. Presynaptic AChE localized in the gap between axon terminal and Schwann cell appears to be resistant to collagenase but not to papain treatment. The mode of AChE attachment or the composition of the intercellular material in this gap may differ from that of the primary and secondary clefts.
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PMID:Attachment of acetylcholinesterase to structures of the motor endplate. 22 95

1. Postsynaptic responses to acetylcholine released from nerve terminals and from iontophoretic micropipettes were investigated in skeletal twitch-muscle fibers of the snake. The preparation consists of thin sheets of muscle fibers in which details of the end plate, including the outlines of individual synaptic boutons, are clearly seen in the living state. After treatment with collagenase, the motor nerve and its terminal boutons can be removed to expose the intact subsynaptic membrane to direct application of ACh by iontophoretic pipettes. 2. The number of ACh molecules in a quanta was estimated to be fewer than 10,000. This was done by developing a sensitive bioassay to measure the output of ACh from iontophoretic pipettes needed to produce synaptic responses closely resembling nerve-released miniature postsynaptic potentials. 3. Postsynaptic receptors are not saturated by the ACh in a quantum, since the peak of the quantal response produced by an appropriate background concentration of ACh from a pipette. 4. When acetylcholine esterase is inhibited, two or more quanta can act upon partially overlapping postsynaptic membrane areas and potentiate each other's effects. This potentiation reveals itself as a prolongation of the synaptic current. Postsynaptic potentiation is a consequence of the nonlinear dose-response characteristics of ACh receptors and can also be demonstrated in a model system in which ACh micropipettes substitute for quantal release from the nerve. 5. With AChE fully active, however, each quantum is functionally isolated from its neighbors and no postsynaptic potentiation is seen. 6. It is suggested that postsynaptic potentiation between quantum may play a role in signaling at synapses which have nonlinear dose-response characteristics and where transmitter is not so rapidly inactivated as at the neuromuscular synapse.
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PMID:The number of acetylcholine molecules in a quantum and the interaction between quanta at the subsynaptic membrane of the skeletal neuromuscular synapse. 106 24

Cultures of rat myotubes from 18-day-old embryos produce both globular (G) and asymmetric (A) forms of acetylcholinesterase (AChE; EC 3.1.1.7), mostly G1, G4, and A12 and a small proportion of A8. We show that all forms are partly intracellular and partly exposed to the extracellular medium; the A forms and their intra- and extracellular distribution are not modified when myotubes are grown in the presence of spinal cord neurons. In these cocultures, however, AChE patches may be detected immunohistochemically at sites of neuromuscular contacts. These patches represent a very minor proportion of AChE activity. We found that collagenase removes AChE patches but not the acetylcholine receptor clusters with which they coincide. This digestion specifically decreases the level of the A12 form. cis-Hydroxyproline, an inhibitor of collagen synthesis, reduces the level of G1 and blocks the synthesis of A forms.
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PMID:Acetylcholinesterase in cocultures of rat myotubes and spinal cord neurons: effects of collagenase and cis-hydroxyproline on molecular forms, intra- and extracellular distribution, and formation of patches at neuromuscular contacts. 215 53

AChE activity was detected mainly in membrane-bound fractions in the frontal cortex of autopsied control or Alzheimer brain as well as rat cerebral cortex. However, the distribution of AChE among various membrane fractions was different between control and Alzheimer brains. The highest specific activity was detected in the fraction enriched with senile plaque, which was obtained from the Alzheimer brain by sonication, solubilization with detergent and centrifugation on a sucrose density gradient. The senile plaque enriched fraction was incubated with purified collagenase or protease and centrifuged at 100,000 g for 60 min. More than 50% of AChE activity was detected in the supernatant fraction. AChE in the supernatant solution showed a property of G4 isozyme. AChE might probably be anchored to the senile plaque through its collagen tail and be solubilized with collagenase or protease, producing a G4 isozyme.
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PMID:Subcellular distribution of acetylcholinesterase in Alzheimer's disease: abnormal localization and solubilization. 239 13

Acetylcholinesterase (EC 3.1.1.7.; AChE) and butyrylcholinesterase (EC 3.1.1.8.; BuChE) from chicken muscle exist as sets of structurally homologous forms with very similar properties. The collagenase sensitivity and aggregation properties of the 'heavy' forms of both enzymes indicate that they possess a collagen-like tail, and their stepwise dissociation by trypsin confirms that they correspond to triple (A12) and double (A8) collagen-tailed tetramers. In addition to this dissociating effect, trypsin digests an important fraction of the catalytic units of AChE, in a progressive manner, removing as much as 30% of the enzyme's mass, without inactivation of the tetramers and of the tailed molecules. The trypsin-modified AChE forms closely resemble the corresponding mammalian AChE forms in their hydrodynamic properties. It is not known whether the trypsin-digestible peptides, which do not appear to be involved in the ionic or hydrophobic interactions of the enzymes, are a fragment of the catalytic subunit or whether they constitute distinct polypeptides.
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PMID:The quaternary structure of chicken acetylcholinesterase and butyrylcholinesterase; effect of collagenase and trypsin. 625 92

We have distinguished three fractions of acetylcholinesterase (AcChoE; acetylcholine acetylhydrolase, EC 3.1.1.7) from Torpedo marmorata electric organs, according to their solubilization characteristics. The low-salt-aggregating collagen-tailed forms are soluble in high-salt buffers; their hydrodynamic properties ae not modified in the presence of detergents. They constitute the A fraction, which amounts to about a third of the tissue's AcChoE activity. The low-salt-soluble (LSS) and detergent-soluble (DS) fractions are not sensitive to ionic strength and collagenase. In the presence of nonionic detergents or bile salts, both fractions behave as a monodisperse "6.3S" form, the properties of which have been investigated mostly in the case of Triton X-100. Disulfide bond reduction dissociates the detergent form into a smaller "5S" form. These two forms are thought to be, respectively, detergent-associated dimers and monomers. In the absence of detergent, the LSS fraction is polydisperse: it contains a major 8S component, 11S and 14S components, and faster-sedimenting aggregates, which appear to represent dimers, tetramers, and higher polymers. The heterogeneity of the 8S component in gel filtration suggests that it also contains variable noncatalytic elements. Upon removal of the detergent the DS fraction forms ill-defined aggregates. Trypsin induces quaternary rearrangements of part of the 8S component into 11S and 14S components, which are still convertible into the detergent form; therefore trypsin probably digests noncatalytic elements. Pronase and proteinase K, on the other hand, convert the enzyme into a dimeric form, G2, that does not interact with detergents, probably by cleaving a minor fragment of the subunit that is involved in hydrophobic interactions.
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PMID:Collagen-tailed and hydrophobic components of acetylcholinesterase in Torpedo marmorata electric organ. 693 97

The levels and molecular forms of acetylcholinesterase (AChE, EC 3.1.1.7) and pseudocholinesterase (psiChE, EC 3.1.1.8) were examined in various skeletal muscles, cardiac muscles, and neural tissues from normal and dystrophic chickens. The relative amount of the heavy (Hc) form of AChE in mixed-fibre-type twitch muscles varies in proportion to the percentage of glycolytic fast-twitch fibres. Conversely, muscles with higher levels of oxidative fibres (i.e., slow-tonic oxidative-glycolytic fast-twitch, or oxidative slow-twitch) have higher proportions of the light (L) form of AChE. The effects of dystrophy on AChE and psiChE are more severe in muscles richer in glycolytic fast-twitch fibres (e.g., pectoral or posterior latissimus dorsi, PLD); there is no alteration of AChE or psiChE in a slow-tonic muscle. In the pectoral of PLD muscles from older dystrophic chickens, however, the AChE forms revert to a normal distribution while the pesChE pattern remains abnormal. Muscle psiChE is sensitive to collagenase in a similar way as is AChE, thus apparently having a similar tailed structure. Unlike skeletal muscle, cardiac muscle has very high levels of psiChE, present mainly as the L form; AChE is present mainly as the medium (M) form, with smaller amounts of L and Hc. The latter pattern of AChE forms resembles that seen in several neural tissues examined. No alterations in AChE or psiChE were found in cardiac or neural tissues from dystrophic chickens.
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PMID:Comparison of the molecular forms of the cholinesterases in tissues of normal and dystrophic chickens. 706 26

The developmental profiles of the enzyme acetylcholinesterase, and of some of its quaternary structural forms, characterized by discrete sedimentation coefficients, have been comparatively analyzed in chick retina and optic tectum, between embryonic day 8 and day 10 after hatching. Four molecular species of AChE have been characterized in both retina and tectum during this developmental period: two of them with sedimentation coefficients of 11S and 6S, accounting together for 94-99% of the AChE activity in the initial homogenate, can be easily extracted by homogenization in a buffer containing 1% Triton X-100 and 1 M NaC1, at 4 degrees C. The other two, however, are not extractable by such treatment, but can be released by collagenase from the residue left after the detergent-salt extraction; they have apparent sedimentation coefficients of 21.5S and 16.5S and represent, together, less than 2% of activity in the initial homogenate. All four forms of the enzyme show distinctive patterns of change during the developmental period considered, with significant differences between retina and tectum. These differences are discussed in the context of the specific roles of retina and tectum in the visual process.
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PMID:Molecular forms of acetylcholinesterase in the developing chick visual system. 721 2

Rat obturator nerve 16S acetylcholinesterase (16S AChE) was separated by sucrose gradient velocity sedimentation and compared to the 16S form of AChE similarly derived from endplate regions of anterior gracilis muscles. The 16S AChE from both tissues could only be extracted in high ionic strength buffer; as it aggregated under low ionic strength conditions. Treatment of nerve and muscle 16S AChE with purified collagenase, in the presence of calcium, caused an identical "shift" in the enzyme's sedimentation coefficient to 17.5S. Other properties which were also equivalent for 16S AChE from both tissue sources included: an excess substrate inhibition above 2 x 10(-3) M acetylcholine and Km of 1.6 x 10(-4) M, relative sensitivity to the specific inhibitors BW284C51 (I50 of 5 x 10(-8) M) and Iso-OMPA (I50 of 5 x 10(-4) M), and a half maximal thermal inactivation at 62.5 degrees C. These and additional results indicate that the 16S forms of AChE in both tissues are analogous molecules, which have a highly asymmetric conformation probably containing a collagen-like domain. The present findings are also consistent with the view that motor neurons provide at least a fraction of the 16S AChE present at the neuromuscular junction.
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PMID:Properties of 16S acetylcholinesterase from rat motor nerve skeletal muscle. 732 60

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


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