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)

The digestive juice of Achatina balteata, a giant snail of the West African Coast catalyses the hydrolysis of several natural and synthetic compounds. Enzymatic activities on lactose, o- and p-nitrophenyl-beta-D-galactoside, p-nitrophenyl-beta-D-glucoside, p-nitrophenyl-beta-D (and alpha-L-) fucoside, o-nitrophenyl-beta-D-xyloside, p-nitrophenyl-N-acetyl-beta-D-glucosaminide and phenolphthalein-glucuronide have been shown to be present. The effect of pH and substrate concentration on these activities were studied. The galactosidase, glucosidase and fucosidase activities were studied with respect to temperature, heat inactivation, pH stability and incubation with trypsin. Kinetic experiments suggest the presence of several galactosidase activities. This hypothesis is confirmed by specific staining after polyacrylamide gel electrophoresis. These activities showed a broad specificity towards galactosides and glucosides. The digestive juice showed no action on acetyl-L-tyrosine and benzoyl-L-arginine ethyl esters. However a small protease activity was observed on hemoglobine. No lipase activity was found. Sulfatase content was low compared to that of Helix pomatia.
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PMID:[Characterization of some hydrolase activities in digestive juice of Achatina balteata]. 0 61

Extracts of the marine polychaetous annelid, Amphitrite ornata, agglutinate rat, rabbit, chicken and human erythrocytes and in other work have been shown to inhibit the growth of Ehrlich ascites tumors in mice. Fractionation of extracts on Sephadex G-100 gave three active fractions with molecular weights of 30 000, 54 000 and 100 000. The 30 000 dalton fraction (B) was purified 72-fold by ammonium sulfate precipitation, gel filtration and preparative disc gel electrophoresis. The purified hemagglutinin, amphitritin, was homogenous on analytical disc gel electrophoresis at four different pH values and gave a sharp boundary in sedimentation velocity ultracentrifugation. The three fractions showed paralled specificity toward rat and chicken erythrocytes, the former giving the higher titer. The purified agglutinin was active toward human blood groups A, B and O and exhibited 4-fold higher activity toward group A. The hemagglutinin titer against rat red blood cells was lowered only by N-acetylgalactosamine, the terminal sugar residue of the group A determinant. None of the saccharides tested inhibited agglutination of chicken erythrocytes. Hemagglutinin activity was insensitive to dialysis or treatment with EDTA. The activity was not affected by digestion with trypsin or pronase, but was destroyed by phenol extraction. Analytical disc gel electrophoresis showed one protein band with high anodal mobility at pH 8.5, which was not affected by proteolytic enzymes but was removed by phenol. Activity was unaffected by heating at 70 degrees C for 30 min but was destroyed by similar treatemtn at 85 degrees C. Activity was at a maximum at pH 7-9 and decreased reversibly down to pH 4 at which point it was irreversibly inactivated. The higher molecular weight agglutinin (A1) could be dissociated to give amphitritin by treatment with 6M urea of precipitation in 55% (NH4)2SO4. This dissociation was not reversed by dialysis. Amphitritin is a glycoprotein with a molecular weight determined by gel filtration of 30 000 and by approach to equilibrium sedimentation of 32 000. Amino acid analysis showed a preponderance of aspartic and glutamic acids and relatively large amounts of glycine, proline, alanine, valine and cysteine. The carbohydrate moeity which represented 12.8% of the molecule, contained mannose, galactose, glucosamine and sialic acid. Amphitritin is the first hemagglutinin to be isolated from a polychaetous annelid.
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PMID:Isolation and characterization of a hemagglutinin from Amphitrite ornata, a polychaetous annelid. 0 17

We have investigated the interaction between concanavalin A-agarose (Con A-agarose) and thyroid peroxidase, an integral membrane protein found in the 105,000 X g, 1-h particulate fraction of thyroid tissue. An intact form of porcine thyroid peroxidase was obtained by solubilization with the nonionic detergent Triton X-100 and two fragmented, hydrophilic forms of the enzyme were prepared by trypsin treatment of the membrane. The three types of thyroid peroxidase bind to Con A-agarose and can be eluted with alpha-methyl-D-mannoside. The alpha-methyl-D-mannoside eluate of the most purified thyroid peroxidase preparation has been analyzed by polyacrylamide gel electrophoresis. Peroxidase activity corresponds with a glycoprotein band. The binding of thyroid peroxidase to Con A-agarose can be inhibited by sugars in the following order: alpha-methyl-D-mannoside greater than D-mannose greater than alpha-methyl-D-glucoside greater than D-glucose greater than D-galactose. This order of specificity is typical of Con A-sugar interactions. Furthermore, inactivation of the carbohydrate binding site of Con A by demetallization greatly reduces the extent of thyroid peroxidase binding. Reactivation of the carbohydrate binding site by the addition of Ca2+ and Mn2+ to demetallized Con A-agarose restores thyroid peroxidase binding. These and other experiments suggest that htyroid peroxidase is, like several other peroxidases, a glycoprotein. In addition, the interaction between thyroid peroxidase and Con A-agarose may provide a new purification tool for thyroid peroxidase.
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PMID:Interaction of thyroid peroxidase with concanavalin A covalently coupled to agarose. 1 48

We have demonstrated binding of purified pili from a strain of Escherichia coli to Vero cell monolayers as a model of prokaryotic-eukaryotic cell adherence. Pili bound to the tissue culture in a rapid reaction that did not require enzymatic activation. Attachment occurred optimally at pH 4-5 and could be inhibited by analogues of D-mannose, anti-pili antibodies, or by preincubation of tissue cells with mannose-specific plant lectins. Binding remained after treatment of the monolayer with glycosidases, trypsin, or a protease mixture but was enhanced after neuraminidase treatment. These results indicate that bacterial binding can occur via pili which act like lectins and presumably bind to mannose-containing glycoproteins on mammalian cell surfaces.
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PMID:Type I Escherichia coli pili: characterization of binding to monkey kidney cells. 2 33

Phosphodiesterase activity is estimated in extracts and partially purified preparations from functionally different parts of bovine tongue. The enzyme activity varied from 4.0 to 10.4 nmole/mg of protein/min. Properties of phosphodiesterase from circumvallate papillae are studied, the pH optimum being 8.0--8.5, Km for cAMP--1.5.10(-4) M and for cGMP--6.5.10(-5) M. The enzyme activity did not change after the treatment with trypsin, protamine sulphate (0.01--1.0%), heparin (0.01--1.0) and taste agents: L-leucine (from 1.10(-2) M to 1.10(-5) M), quinine (from 4.10(-3) M to 4.10(-8) M) and D-glucose (from 1.10(-1) M to 1.10(-4) M). The protein inhibitor of the enzyme, isolated from retina external rod-cell segments considerably suppressed phosphodiesterase activity, and the protein activator from brain tissue stimulated it insignificantly. Thermostable protein modulators, which inhibit or activate (depending on experimental conditions) phosphodiesterase activity, are isolated from circumvallate papillae.
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PMID:[Properties of cyclic nucleotide phosphodiesterase from lingual taste papillae]. 2 46

Cross-reactive antigens of clover roots and Rhizobium trifolii were detected on their cell surfaces by tube agglutination, immunofluorescent, and radioimmunoassay techniques. Anti-clover root antiserum had a higher agglutinating titer with infective strains of R. trifolii than with noninfective strains. The root antiserum previously adsorbed with noninfective R. trifolii cells remained reactive only with infective cells, including infective revertants. When adsorbed with infective cells, the root antiserum was reactive with neither infective nor noninfective cells. Other Rhizobium species incapable of infecting clover did not demonstrate surface antigens cross-reactive with clover. Radioimmunoassay indicated twice as much antigenic cross-reactivity of clover roots and R. trifolii 403 (infective) than R. trifolii Bart A (noninfective). Immunofluorescence with anti-R. trifolii (infective) antiserum was detected on the exposed surface of the root epidermal cells and diminished at the root meristem. The immunofluorescent crossreaction on clover roots was totally removed by adsorption of anti-R. trifolii (infective) antiserum with encapsulated infective cells but not with noninfective cells. The cross-reactive capsular antigens from R. trifolii strains were extracted and purified. The ability of these antigens to induce clover root hair deformation was much greater when they were obtained from the infective than noninfective strains. The cross-reactive capsular antigen of R. trifolii 403 was characterized as a high-molecular-weight (greater than 4.6 times 10(6) daltons), beta-linked, acidic heteropolysaccharide containing 2-deoxyglucose, galactose, glucose, and glucuronic acid. A soluble, nondialyzable, substance (clover lectin) capable of binding to the cross-reactive antigen and agglutinating only infective cells of R. trifolii was extracted from white clover seeds. This lectin was sensitive to heat, Pronase, and trypsin. inhibition studies indicated that 2-deoxyglucose was the most probable haptenic determinant of the cross-reactive capsular antigen capable of binding to the root antiserum and the clover lectin. A model is proposed suggesting the preferential adsorption of infective versus noninfective cells of R. trifolii on the surface of clover roots by a cross-bridging of their common surface antigens with a multivalent clover lectin.
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PMID:Cross-reactive antigens and lectin as determinants of symbiotic specificity in the Rhizobium-clover association. 5

Rosette formation with unsensitized sheep erythrocytes is a characteristic of human thymus dependent lymphocytes. Release of glycopeptides from the sheep erythrocyte by trypsin reduces rosette formation. These tryptic glycopeptides inhibit rosette formation by untrypsinized sheep erythrocytes; this suggests that rosetting is mediated by erythrocyte surface glycopeptides. To investigate the molecular nature of this interaction, we examined the abilities of various model compounds to act as haptenic inhibitors of rosette formation. Inhibition is given by glycopeptides bearing oligosaccharide units rich in sialic acid, galactose, N-acetylglucosamine, and mannose linked to asparagine residues through glycosylamine bonds. Among compounds tested, fetuin glycopeptide is most effective, but human transferrin glycopeptide and human erythrocyte glycopeptide I also inhibit rosette formation. Other compounds including human erythrocyte glycopeptide II, human IgG glycopeptide, lacto-N-neotetraose, 3'- and 6'-sialyllactose show no significant inhibition. Neither sialic acid, galactose, manose, nor N-acetyl-glucosamine alone inhibits rosette formation. Stepwise degradation of fetuin glycopeptide established the galactose residues as important determinants of inhibitory activity. Fetuin glycopeptide blocks rosette formation when added to a suspension of human lymphocytes and sheep erythrocytes or when preincubated with human lymphocytes, but not when preincubated with sheep erythrocytes. Studies of the binding of [3H] fetuin glycopeptide to normal lymphocytes demonstrate 7.5 x 10(6) saturable binding sites per cell. No saturable binding of this compound to sheep erythrocyte membranes is observed. Compared to normals, lymphocytes from patients with chronic lymphatic leukemia demonstrate decreased fetuin glycopeptide binding with a mean of 0.9 x 10(6) sites per cell. This decreased binding correlates with the impaired ability of these cells to form rosettes. The data suggest that fetuin glycopeptide inhibits rosette formation by binding to the thymus-dependent cell where competition occurs with sheep erythrocytes for specific lymphocyte surface receptors.
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PMID:Rosette formation between human lymphocytes and sheep erythrocytes. Inhibition of rosette formation by specific glycopeptides. 5 39

A simple method using a cationic dye, toluidine blue (TB), to quantify changes of red cell membrane area has been developed and tested for its validity. After incubating a glucose-depleted red cell suspension with a fixed quantity of TB at 37 degrees C for 10 min, the remaining TB was measured spectrophotometrically at 640 nm. Using this technique, we were able to show differences in TB uptake by populations of young and old red cells. The exact mechanism for TB uptake by the red cells is not clear. Treatment of the cells with bromelin, papain and trypsin reduced the uptake of TB, but neuraminidase and ficin had little or no effect. No inhibition of TB removal by red cells was observed using heparin, D-glucose, glucuronic acid, or N-acetylglucosamine.
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PMID:Evaluation of toluidine blue for measuring erythrocyte membrane loss during in vivo ageing. 8 Oct 69

The present experiments demonstrate that animals carrying large peripheral intramuscular tumours were free of spontaneous pulmonary metastases. Secondaries in the lung emerged, however, after administration of agents such as trypsin, 10% dextrose or antiserum to alpha-2-macroglobulin (AMG). Such metastases also appeared in animals treated with trypsin after amputation of the tumour-bearing limb. It is believed that the pulmonary vessels of tumour-bearing animals are lined with a layer of tumour-associated AMG. The presence of this peptide on vascular endothelium blocks the transmigration of tumour cells. Tumour emboli may remain dormant, i.e. unattached, in the vascular lumen. Agents inactivating AMG or enhancing vascular permeability (proteases, antisera to AMG or vasodilators) may promote the emergence of a latent tumour cell into an overt state. This is confirmed by the above experiments and by the microscopic appearance of the pulmonary vessels of test animals (shift of tumour cells from the intravascular to the perivascular space). It is suggested that latency is determined by the state of permeability of the vessels harbouring tumour emboli.
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PMID:On the latency of tumour cells. 8 78

The heat-labile enterotoxin (LT) has been isolated in homogeneous form with high specific activity from three sources: cell-free supernatant, NaCl extract, and whole-cell lysates of an enterotoxigenic Escherichia coli strain. In vitro immunological assays were used in lieu of tedious and highly variable bioassays to recognize fractions with activity. This revealed that the major portion of the LT remained adherent to columns containing agarose, from which it could be eluted quantitatively in practically homogeneous form by galactose. Isolated LT has remarkable similarities to the cholera enterotoxin (choleragen) in both subunit structure and amino acid composition, although there are also notable differences in these two enterotoxins, which are related immunologically and by mode of action. Unlike choleragen, in which the A region is totally nicked, E. coli LT, depending on its source, is activated by proteolytic processing. The activity of LT is equivalent to that of choleragen in bioassays on adrenal cells, in rabbit skin, and in rabbit ileal loops, especially when, depending on the source of material, the LT has been activated by treatment with trypsin. The whole-cell lysate is the richest source of LT.
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PMID:Isolation and characterization of homogeneous heat-labile enterotoxins with high specific activity from Escherichia coli cultures. 8 88


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