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:3.4.21.1 (chymotrypsin)
10,938 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Stereospecific high-affinity binding sites for beta h-[3H]endorphin could be demonstrated in the P2 pellet of rat brain homogenate. Scatchard analysis of the binding data revealed binding sites with Kd values of 0.81 and 6.8 nM and density of 120 and 240 fmol/mg of protein. Distribution of beta h-[3H]endorphin binding in various brain regions parallels that of opiate receptor:striatum greater than thalamus greater than amygdala greater than hypothalamus, septum greater than cortex greater than midbrain, brainstem. Similar to their effect on 3H-labeled agonist binding, Na+ and other monovalent cations, GTP, trypsin, chymotrypsin, phospholipase A2, and N-ethylmaleimide all inhibited the specific binding of beta h-[3H]endorphin. In contrast to their action on alkaloid and enkephalin binding, Ca2+, Mg2+, and Mn2+ also inhibited beta h-[3H]endorphin binding. These data suggest a difference between beta h-endorphin and alkaloid/enkephalin binding sites.
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PMID:Properties and localization of beta-endorphin receptor in rat brain. 23 Apr 77

Carrageenan or thrombin-induced aggregation of plasma-free rabbit platelets was inhibited by calcium and magnesium chelating agents, by N-ethylmaleimide and by drugs that increase the intra-cellular cyclic AMP content. Inhibitors of prostaglandin (PG) synthetase were only partially active, and had to be present in the platelet suspension to inhibit aggregation. Inhibition of PG synthetase, as evaluated by bioassay and by AA-induced platelet aggregation, was not reduced when inhibitors were washed from platelets. The phospholipase A2 inhibitors bromophenacyl bromide and mepacrine, the chymotrypsin inhibitor tosylphenylalaninechloromethylketone, catalase and dithiothreitol also inhibited aggregation, whereas inhibitors of trypsin failed to do so. Incubation of rabbit platelet-rich plasma with carrageenan was followed by generation of PG-like and of rabbit aorta contracting activities. Generation of these activities was inhibited by drugs effective against aggregation, and also by non-steroidal anti-inflammatory drugs. Aggregation of rabbit platelets by carrageenan and by thrombin does not appear to be dependent upon activation of PG synthetase, although PG-like substances are formed during aggregation.
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PMID:Involvement of mediators in the interaction of platelets and carrageenan. 41 34

The calcium dependence and the time course of phosphatidylethanolamine and phosphatidylcholine degradation by sheep erythrocyte membrane suspensions in presence of Triton X-100 were investigated. One enzyme with phospholipase A2 specificity was found to be responsible for both phosphatidyl-ethanolamine and phosphatidylcholine degradation. The localization of this enzyme in the membrane of the sheep erythrocyte was investigated by proteolytic treatment of sealed erythrocyte ghosts from the outside and of ghosts which had both sides of the membrane exposed to chymotrypsin. The inability of sealed ghosts to take up chymotrypsin was followed by flux measurements of [14C]dextran carboxyl previously trapped in the ghosts. No efflux of the marker was found during the proteolytic treatment. By comparing the residual phospholipase activities in the membranes from both ghost preparations, we concluded that the phospholipase is oriented to the exterior of the sheep erythrocyte.
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PMID:Phospholipase A2 from sheep erythrocyte membranes. Ca2+ dependence and localization. 42 Aug 27

The complete amino acid sequence of phosphlipase A2 (EC 3.1.1.4) from horse pancreas was determined. The protein controls of a single polypeptide chain of 125 amino acids and has a molecular weight of 13,927. The chain is crosslinked by seven disulfide bridges. The sequence was determined by automated Edman degradation of the intact protein and several of the large peptide fragments. Smaller peptides were analyzed by manual Edman degradation. Fragmentation of the peptide chain was accomplished by enzymatic digestion with trypsin, chymotrypsin, and thermolysin. The final overlap was found by digestion of the polypeptide with a staphylococcal protease specific for glutamoyl bonds. Phospholipase A2 from horse pancreas shows homology to snake venom phospholipases A2 and to the enzyme from porcine pancreas, provided that the published amino acid sequence of the porcine phospholipase A2 is revised to some extent.
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PMID:Amino acid sequence of phospholipase A2 from horse pancreas. 83 12

In order to covalently bind the hydrolyzed thiol ester groups of the human alpha 2-macroglobulin (alpha 2M) transformed by methylamine, the phospholipase A2 (PLA2), a small enzyme (M(r) = 13,000) from Naja nigricollis snake venom was activated by succinimidyl 4-(maleimidomethyl)cyclohexane-1-carboxylate (SMCC). Average images determined from electron micrographs of the methylamine-transformed alpha 2M, with and without activated PLA2, were determined by image processing and compared. A localization of the PLA2 was achieved by subtracting the average image of alpha 2M transformed by methylamine from that containing PLA2. The results are consistent with previous work showing the central localization of chymotrypsin trapped in alpha 2M. They also suggest that the four thiol esters are located near the center of the alpha 2M molecule.
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PMID:Electron microscopy of alpha 2-macroglobulin with a thiol ester bound ligand. 128 56

Changes in the activities of three gastric and nine pancreatic enzymes plus colipase were determined during postnatal development and weaning in calves. In calves exclusively milk-fed for 2, 7, 28, 56, 70 and 119 d, the enzyme activities per kilogram of empty live weight increased with age for chymotrypsin, elastase, carboxypeptidases A and B, ribonuclease and alpha-amylase, decreased for chymosin, lysozyme and colipase but showed no change in the case of pepsin, trypsin, lipase and phospholipase A2 compared with animals at birth. The greatest increase was that in alpha-amylase activity (about 50-fold between d 2 and 119). In calves weaned between d 28 and 56, all the activities were higher than in milk-fed animals, except that of chymosin (which was slightly lower) and that of colipase (which did not change). At 119 d of age, chymotrypsin, carboxypeptidase A, alpha-amylase and lipase were 1.6- to fourfold higher in ruminants than in preruminants. Thus, most enzyme activities were modified first by colostrum and milk intake, and again upon weaning by development of the forestomachs and ingestion of solid food. These ontogenic patterns might be under the control of many gut regulatory peptides, the plasma concentrations of which changed simultaneously. Some gastric and pancreatic enzymes were correlated to plasma concentrations of these gut regulatory peptides.
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PMID:Gastric and pancreatic enzyme activities and their relationship with some gut regulatory peptides during postnatal development and weaning in calves. 137 46

When the effect of MY-1250 (5,6-dihydro-7,8-dimethyl-4,5-dioxo-4 H-pyrano [3,2-c] quinoline-2-carboxylic acid) on histamine release from rat peritoneal mast cells induced by compound 48/80 was studied, MY-1250 caused a significant inhibition of histamine release at concentrations higher than 3 microM. Furthermore, the compound inhibited not only 45C a uptake into the mast cells but also Ca2+ release from the intracellular Ca store at a concentration of 10 microM in both cases. By contrast, MY-1250 did not affect either histamine release from permeabilized mast cells induced by TPA, IP3 and GTP gamma S or Ca2+ release from the endoplasmic reticulum induced by IP3. In the chopped lung preparations, MY-1250 at doses of 10 and 100 microM caused a significant inhibition in histamine release from the pieces of actively sensitized guinea pigs exposed to antigen and simultaneously prevented a decrease in intracellular cAMP contents taking place in association with antigen-antibody reaction. No significant changes were effected by MY-1250 in alpha-chymotrypsin activity and phospholipase A2 activity. Also, no antagonistic effects on LTD4 and PAF were observed.
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PMID:Inhibitory effect of MY-1250 on histamine release from rat peritoneal mast cells and guinea pig lung fragments: the elucidation of the mechanism. 171 61

1. Methacholine relaxed phenylephrine-contracted aorta of the rat with the endothelium intact. This effect was inhibited by haemoglobin, methylene blue, gossypol, phenidone and L-NG-nitroarginine methyl ester (L-NAME). Rat aorta denuded of endothelium failed to relax in response to methacholine, histamine and the peptidoleukotrienes C4, D4 and E4. 2. Methacholine and histamine but not leukotrienes C4, D4 and E4 relaxed phenylephrine-contracted rat aorta without endothelium when surrounded by rabbit epithelium-intact bronchus. The muscarinic antagonist atropine antagonized the methacholine-induced relaxation. 3. Removal of the epithelium either mechanically or chemically, abolished methacholine-induced relaxation of rat aorta in the co-axial bioassay. These data indicate that the epithelium is responsible for the observed relaxant effect to methacholine and histamine. 4. The cyclo-oxygenase inhibitor, indomethacin, the phospholipase A2 inhibitor, mepacrine and the lipoxygenase inhibitor, nordihydroguaiaretic acid (NDGA), failed to inhibit methacholine-induced relaxation of rat aorta in the co-axial bioassay. This indicates that the epithelium-derived inhibitory factor (EpDIF) is not a product of the cyclo-oxygenase or lipoxygenase pathway or a product derived from activation of phospholipase A2. 5. Haemoglobin, methylene blue, phenidone, gossypol and L-NAME failed to inhibit the relaxation of rat aorta in the co-axial bioassay. These results demonstrate that EpDIF detected in the co-axial bioassay is not endothelium-derived relaxing factor (EDRF) or nitric oxide. Similarly, catalase was without effect. 6. EpDIF is unlikely to be a peptide since papain and alpha-chymotrypsin failed to alter the methacholine-induced relaxation of rat aorta in the co-axial bioassay. Furthermore, thiorphan, captopril and aprotinin were also without effect, suggesting that EpDIF is not a substrate for airway peptidases. 7. The results presented in this paper demonstrate the release of a vasoactive epithelium-derived inhibitory factor (EpDIF) from rabbit intrapulmonary bronchi by use of a co-axial bioassay preparation.
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PMID:The release of a non-prostanoid inhibitory factor from rabbit bronchus detected by co-axial bioassay. 185 18

Three phospholipase A2 enzymes or homologs were purified from the venom of Trimeresurus mucrosquamatus (Taiwan habu). The most abundant one was found to be a phospholipase homolog without enzyme activity, and its complete amino acid sequence was determined using oligopeptide fragments derived from digestion by endopeptidases Glu-C, Asp-N, Lys-C and alpha-chymotrypsin, and by means of gas-phase sequencing. The sequence revealed that the protein belonged to the Lys-49 family of snake venom phospholipase A2. This protein's function was characterized as edema-inducing. The Lys-49 protein has the potential to bind membrane phospholipid and Ca2+ (Kd = 1.6 x 10(-4) M) as shown by ultraviolet difference spectra; however, the catalytic site appeared to be inactive and the edematous response was independent of the protein's hydrolytic activity. Mast cells and platelets were shown to be subject to activation by the Lys-49 protein.
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PMID:The amino acid sequence and properties of an edema-inducing Lys-49 phospholipase A2 homolog from the venom of Trimeresurus mucrosquamatus. 202 35

Two phospholipases A2, named phospholipases A2-I and A2-II, were purified to homogeneity from the venom of Trimeresurus gramineus (green habu snake). The complete amino acid sequence of phospholipase A2-I was determined by sequencing the native protein and the peptides produced by enzymatic (Achromobacter protease I, clostripain, and chymotrypsin) and chemical (hydroxylamine) cleavages of the S-pyridylethylated derivative of the protein. The protein consisted of 122 amino acid residues and was similar in sequence to phospholipases A2 from the venoms of crotalid snakes which belong to the category of Group II. A most striking feature of this protein is that tyrosine at the 28th position which is common in phospholipases A2 and is assumed to be a part of the Ca2(+)-binding loop is replaced by phenylalanine. Such replacement is the first finding in Group II phospholipases A2. Secondary structure compositions of phospholipase A2-I are similar to those of Crotalus atrox phospholipase A2. No appreciable Ca2(+)-induced difference spectrum was observed, due probably to the absence of the effective chromophoric groups in the neighborhood of the Ca2+ binding site although Ca2+ is bound with affinity similar to that for T. flavoviridis phospholipase A2.
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PMID:Amino acid sequence of a phospholipase A2 from the venom of Trimeresurus gramineus (green habu snake). 204 35


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