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:3.4.21.4 (trypsin)
42,187 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

A soluble protein termed "supernatant protein factor" (SPF) that stimulates microsomal squalene epoxidase has been isolated in this laboratory (Ferguson, J.B., and Bloch, K. (1977) J. Biol. Chem. 252, 5381-5385). We now show that the purified protein also stimulates microsomal squalene-2,3-oxide leads to lanosterol cyclase but has no effect on the subsequent conversion of lanosterol to cholesterol. Phospholipid, specifically phosphatidylglycerol or phosphatidylethanolamine, is required for maximal stimulation of the cyclase by purified SPF. The response of microsomal squalene epoxide-lanosterol cyclase to SPF was abolished by pretreatment of the membranes with phospholipase A2 or by low concentrations of deoxycholate, indicating that an intact membrane system is required. Digestion of intact microsomes with trypsin had no effect on the SPF-stimulated cyclase activity. However, in the presence of 0.4% deoxycholate, trypsin completely inhibited microsomal squalene epoxide-lanosterol cyclase. We conclude that the cyclase is located on the luminal side of the microsomal membrane. SPF also significantly enhances the formation of lanosterol from squalene-2,3-oxide already bound to microsomes. This finding is constant with the proposal that SPF influences intramembrane events.
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PMID:Effects of a supernatant protein activator on microsomal squalene-2,3-oxide-lanosterol cyclase. 50 Jun 76

The binding and phospholipase A2 activity of an 11,000-dalton beta-bungarotoxin, isolated from Bungarus multicincutus venom, have been characterized using rat brain subcellular fractions as substrates. 125I-labeled beta-bungarotoxin binds rapidly (k = 0.14 min-1 and 0.11 min-1), saturably (Vmax = 130.1 +/- 5.0 fmoles/mg and 128.2 +/- 7.1) fmoles/mg), and with high affinity (apparent Kd = 0.8 +/- 0.1 nM and 0.7 +/- 0.1 nM) to rat brain mitochondria and synaptosomal membranes, respectively, but not to myelin. The binding to synaptosomal membranes is inhibited by divalent cations and by pretreatment with trypsin. The binding results suggest that the toxin binds to specific protein receptor sites on presynpatic membranes. The 11,000-dalton toxin rapidly hydrolyzes synaptosomal membrane phospholipids to lysophosphatides and manifests relative substrate specificity in the order phosphatidyl ethanolamine greater than phosphatidyl choline greater than phosphatidyl serine. These results indicate that the 11,000-dalton beta-bungarotoxin is a phospholipase A2 and can use presynaptic membrane phospholipids as substrates. The binding, phospholipase activity and other biological properties of the 11,000-dalton toxin are contrasted with those of the beta-bungarotoxin found in highest concentration in the venom (the 22,000-dalton beta-bungarotoxin), and the two toxins are shown to have qualitatively similar properties. Finally the results are shown to support the hypothesis that beta-bungarotoxins act in a two-step fashion to inhibit transmitter release: first, by binding to a protein receptor site on the presynatic membrane associated with Ca2+ entry, and second, by perturbing through enzymatic hydrolyses the phospholipid matrix of the membrane and thereby causing an increase in passive Ca2+ permeability.
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PMID:Characterization of an 11,000-dalton beta-bungarotoxin: binding and enzyme activity on rat brain synaptosomal membranes. 51 91

Trypsin treatment of intact cells or isolated plasmalemmae from embryonic chick neural retinae leads to an accumulation of lysophospholipids in the plasmalemmae. Trypsin was used at activities commonly used in cell disaggregation techniques. This accumulation appears to result from the decrease in acyltransferase activity in the plasmalemma produced by enzyme treatment. Plasmalemmal CoA ligase activity is not affected by trypsin treatment. Trypsinization has little effect on plasmalemmal phospholipase A2 activity. These results are discussed in relation to (a) the effects of trypsinization on cell adhesion, and (b) the theory that cells cannot adhere to lecithins because of their fluidity or surface-free-energy values. We propose that the effects of trypsinization on adhesion may in large part be due to the effects on other plasmalemmal proteins. Similarly the inability of cells to adhere to lecithin substrates is simply explained as being due to the lysolecithin that contacting cells release from these substrates.
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PMID:Cell surface lipids and adhesion. IV. The effects of trypsin on lipid turnover by the plasmalemma. 52 67

The complete amino acid sequence of bovine phospholipase A2 (EC 3.1.1.4) was determined. This enzyme has a molecular weight of 13 782 and consists of a single polypeptide chain of 123 amino acids cross-linked by seven disulfide bridges. The main fragmentation of the polypeptide chain was accomplished by digesting the reduced and thialaminated derivative of the protein with trypsin, staphylococcal protease and cyanogen bromide. A number of chymotryptic peptides were used for alignment and to obtain overlaps of at least two residues. The sequence of the peptides was determined by Edman degradation by means of direct phenylthiohydantoin identification in combination with identification as dansyl amino acids. Although 71% of all residues of phospholipase A2 from bovine, porcine and equine sources are conserved, bovine phospholipase A2 differs from the others by the total number of residues and by substitutions at 20 (porcine) and 33 (equine) positions.
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PMID:The primary structure of bovine pancreatic phospholipase A2. 62 Jun 74

D-beta-Hydroxybutyrate dehydrogenase of beef heart mitochondria is a lipid-requiring enzyme, bound to the inner membrane. The orientation of this enzyme in the membrane has been studied by comparing the characteristics of the enzyme in mitochondria and 'inside-out' submitochondrial vesicles. We observe that the enzymic activity is (1) latent in intact mitochondria; (2) relatively stable to trypsin digestion in mitochondria but rapidly inactivated in submitochondrial vesicles by this treatment; and (3) released more rapidly from submitochondrial vesicles by phospholipase A2 digestion than from mitochondria. Conclusive evidence that D-beta-hydroxybutyrate dehydrogenase is localized on the matrix face of the mitochondrial inner membrane is provided by the correlation that the enzyme is released from submitochondrial vesicles before the membrane becomes leaky to cytochrome c. The arrangement of D-beta-hydroxybutyrate dehydrogenase in the membrane is discussed within a generalized classification of the orientation of proteins in membranes. The evidence indicates that D-beta-hydroxybutyrate dehydrogenase is an amphipathic molecule and as such is inlaid in the membrane, i.e. the enzyme is partially inserted into the hydrophobic milieu of the membrane, with the polar, functional end extending into the aqueous milieu.
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PMID:The orientation of D-beta-hydroxybutyrate dehydrogenase in the mitochondrial inner membrane. 71 94

beta1-Bungarotoxin modified with p-bromophenacyl bromide (BPB) was reduced and carboxymethylated, and the resulting two constituent RCM-polypeptide chains (the RCM-A and B chains) were separated. The RCM-A chain was found to be modified by BPB by measuring its UV absorption spectrum and was shown to have lost one histidine residue by analyzing its amino acid composition. To determine the location of the modified histidine residue in the A chain of the toxin, the RCM-A chain was digested with TPCK-trypsin, and the resulting peptides were fractionated by gel filtration followed by DEAE-cellulose chromatography. The modified residue was finally identified as histidine-48 in the A chain by Edman degradation and from the amino acid composition of the BPB-modified peptide. The amino acid sequence around the modified histidine residue in the A chain is highly homologous with those of porcine pancreas phospholipase A2 and presynaptic toxin, notexin. We conclude that histidine-48 in the A chain participates in the phospholipase A activity of beta1-bungarotoxin.
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PMID:Characterization of phospholipase A activity of beta1-bungarotoxin from Bungarus multicinctus venom. II. Identification of the histidine residue of beta1-bungarotoxin modified by p-bromophenacyl bromide. 73 Jul 54

Isoproteic and lipid-rich diets containing about 15 or 20 % of sun flower triglyceride or soya phospholipids given to rats for 8 weeks were observed to increase lipase, phospholipase A2 and trypsin synthesis in the pancreas phospholipase A2 and trypsin synthesis in the pancreas and the activities of these enzymes in the pancreatic juice (Tables IV, V). Smaller effects are observed after 15 day administration of diets containing 40 % of triglycerids or phospholipids ; these diets decreased the ADN content of pancreas.
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PMID:[Effects of isoproteic and lipid rich diets on lipase, phospholipase A2, cholesterolesterase, trypsin and amylase activities in rat pancreatic juice and pancreas (author's transl)]. 75 26

The effects of a highly-purified, potently bactericidal fraction from rabbit polymorphonuclear leukocytes on the envelope of Escherichia coli (W) have been examined. This leukocyte fraction has equally enriched bactericidal, permeability-increasing and phospholipase A2 activities, and is essentially devoid of lysozyme, myeloperoxidase and protease activities (Weiss, J., Franson, R.C., Beckerdite, S., Schmeidler, K. and Elsbach, P. (1975) J. Clin. Invest. 55, 33-42). Rapid killing of E. coli by this fraction is accompanied by two almost immediate alterations in the bacterial envelope: (1) a discrete increase in envelope permeability (measured by inhibition of bacterial leucine incorporation by normally impermeant actinomycin D), and, (2) hydrolysis of 14C-labeled fatty acid-prelabeled E. coli phospholipids. Both envelope effects are promptly reversed during further incubation at 37 degrees C, But not at 0 degrees C, with 40 mM Mg2+. Reversal is also produced by Ca2+ (40 mM) and trypsin (200 mug/ml), but 200 mM K+ causes only partial recovery and Na+ and hyperosmolar sucrose are ineffective. Upon addition of Mg2+, phospholipid degradation ceases abruptly and the labeled products of hydrolysis (free fatty acids and lysocompounds) disappear with a corresponding reaccumulation of radioactive diacylphosphatides. The time course of resynthesis of phospholipids coincides with that of restoration of the permeability barrier. Higher concentrations of the leukocyte fraction and prolonged incubation increase both the extent of phospholipid degradation and the time required for reversal of both envelope effects. These findings suggest that both the initiation of the increased permeability and its reversal are linked to respectively the breakdown and resynthesis of major E. coli membrane phospholipids, and thus depend on the fact that the biochemical apparatus of E. coli remains capable of biosynthesis despite loss of viability. Treatment of E. coli, exposed to the leukocyte fraction, with albumin results in extracellular sequestration of the products of hydrolysis and also restores the permeability barrier to actinomycin D, suggesting that the accumulation of lytic products of lipid hydrolysis within the bacterial envelope, rather than the loss of phospholipids per se, causes increased permeability Whereas the effects on the envelope are reversible as long as 2 h after nearly complete loss of ability to multiply by E. coli, the effect on bacterial multiplication is irreversible within 5 min.
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PMID:Reversible envelope effects during and after killing of Escherichia coli w by a highly-purified rabbit polymorpho-nuclear leukocyte fraction. 77 27


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