Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.4 (trypsin)
 42,187 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cell free preparations of the whole-cell lysate and ultrafiltration (UF) fractions of broth cultures of a strain of Enterobacter cloacae, isolated from a Puerto Rican with tropical sprue, were assayed for their ability to induce in vivo net water secretion in the rat jejunum. The whole-cell lysate and UM-10 retentate of broth cultures were inactive. The UM-2 retentate and filtrate were active at a concentration of 100 mug/ml or more; the toxigenic activity was entirely retained, and increased to 1 mug/ml, by a UM-05 membrane; washing this retentate yielded a fraction with an activity of 10 ng/ml. Stationary aerobic culture conditions yielded the most active UF fractions when ammonium sulfate was used as the precipitating agent, whereas anaerobic culture conditions produced the most active fractions in broth cultures precipitated by acetone. Passage of the active acetone-precipitated UF fractions through a Sephadex G-25 column yielded eluate pools with enhanced toxigenic activity in, or adjacent to, the void volume, but maximum activity of the ammonium sulfate-precipitated UM-05 retentate eluated at a Kav of 0.38 to 0.52. Neither of the most active gel filtration elution fractions of the UM-05 retentates contained detectable carbohydrate, suggesting that the toxin is not associated with endotoxin. Toxigenic activity was unaltered by exposure to a temperature of 100C for 30 min, lowering the pH to 1, or incubation with either Pronase or trypsin. These observations indicate that the strain of E. cloacae under study elaborates a heat-stable enterotoxin htat has approximately the same molecular weight and shares many of the characteristics of the heat-stable enterotoxin produced by some strains of Escherichia coli and Klebsiella pneumoniae.
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PMID:Partial purification and properties of Enterobacter cloacae heat-stable enterotoxin. 0 76

The metal content of carboxypeptidase Y was analyzed by the atomic absorption method. After exhaustive dialysis against an EDTA solution, the enzyme showed no loss of activity nor any significant content of metals (Zh,Mg,Ca,Cu,Mn,Ni,Fe, and Co). The activity was, however, rather sensitive to preincubation with various metals. The reactivity of a serine residue of the enzyme was also reevaluated. Diisopropyl fluorophosphate (DFP) and phenylmethanesulfonyl fluoride (PMSF) stoichiometrically and irreversively inhibited the enzyme. The rate of inactivation with DFP was much faster than that for typsin [EC 3.4.21.4] and chymotrypsin [EC 3.4.21.1.], while the rate with PMSF was one-fifteenth of that for chymotrypsin. The pH-dependence of the inactivation by DFP was similar to that of the enzymatic hydrolysis of acetylphenylalanine ethyl ester. The present results indicate that carboxypeptidase Y is free of metals and has a serine residue with a vital role in the catalytic process, though the functional role of this SH group remains to be clarified.
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PMID:Further confirmation of carboxypeptidase Y as a metal-free enzyme having a reactive serine residue. 0 4

A low molecular weight active fragment of potato proteinase inhibitor IIPB was obtained by incubating the inhibitor with an equimolar amount of trypsin [EC 3.4.21.4] at pH 8 and 30 degrees for 16 hr, followed by gel filtration through Sephadex G-50, treatment with trichloroacetic acid, and CM-cellulose chromatography. The purified active fragment consisted of a single peptide chain with a molecular weight of 4,300, comprising 39 amino acid residues. It retained very strong inhibitory activity against chymotrypsin [EC 3.4.21.1] and subtilisin [EC 3.4.21.14]. However, the yield of this active fragment was rather low and was variable. On further incubation with trypsin, it was converted into smaller inactive peptides.
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PMID:Isolation of a low molecular weight active fragment of potato proteinase inhibitor IIb. 0 22

The loss in protein synthesis which the regenerating forelimb of the newt suffers after denervation can be recovered by infusing into it an extract of newt soluble brain protein. Moreover, the synthesis of basic protein shows a greater response to the active brain principle than does that of acidic protein. The active agent of the nervous tissue is destroyed by heat and trypsin digestion. Extracts of liver and spleen, similarly prepared, do not evoke recovery of lost protein synthesis. Synaptosomal extracts of the frog brain also cause recovery of protein synthesis in the denervated regenerate, demonstrating the likelihood that the active agent is not species-specific within these amphibians, that it is a constituent of the neuronal fraction of nervous tissue, and that it is present in axonal terminals. Additional experiments showed that the nervous agent is likely a basic protein, and that the amount of protein infused is of the order of only 1.0% of the total regenerate protein. The significance of the findings is discussed in relation to the nature of the effect on protein synthesis and the nature of the active principle.
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PMID:Neurotrophic activity of brain extracts in forelimb regeneration of the urodele, Triturus. 0 74

The reactivity of vesicular stomatitis virus (VSV) with kethoxal can be appreciably altered by treatment with 1-guanyl-3, 5-dimethyl pyrazole nitrate (GDMP) and proteolytic enzymes. Pretreatment of purified VSV with GDMP or proteolytic enzymes markedly reduced the effectiveness of kethoxal as a virucide. The rate of neutralizability of GDMP- and trypsin-treated viruses by specific antiserum differed from that of controls.
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PMID:Diminished virucidal activity of kethoxal against vesicular stomatitis virus pretreated with guanidinating reagent and proteases. 0 66

Pretreatment of chick embryo cells (CEC) with homologous interferon enhanced the subsequent interferon production induced by human adenovirus. This priming effect of interferon pretreatment was also demonstrable when trypsin-treated virus was used for the induction of interferon.
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PMID:Interferon pretreatment primes interferon production by human adenovirus in chick embryo cells. 0 73

Two proteinases (2A and 2B) purified from the granular fraction of horse blood leucocytes degrade casein (Km values 12.8 and 6mg/ml respectively) with maximum activity at pH 7.4 and in the presence of 2m-urea. Urea-denatured haemoglobin, fibrinogen, albumin and resorcin/fuchsin-stained elastin are digested at a slower rate. The enzymes hydrolyse synthetic substrates of elastase, N-benzyloxycarbonyl-L-alanine 4-nitrophenyl ester (Km 0.114 and 0.178 mM) and N-acetyl-tri-L-alanine methyl ester (Km 5.55 and 0.98 mM), but they do not hydrolyse synthetic substrates of trypsin, chymotrypsin and thrombin. The examined proteinases are completely inhibited by 2 mM-di-isopropyl phosphorfluoridate and show a sensitivity to butyl and octyl isocyanates similar to that of pancreatic elastase. The pH-dependence of their photoinactivation in the presence of Rose Bengal indicates the presence of histidine in the active centre. Proteinase 2A rather insensitive to iodination by IC1 as is pancreatic elastase, whereas proteinase 2B is totally inactivated after incorporation of five iodine atoms per enzyme molecule.
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PMID:Substrate specificity and modifications of the active centre of elastase-like neutral proteinases from horse blood leucocytes. 0 9

According to previous authors, cytochrome b5, when extracted from bovine liver by a detergent method, is called cytochrome d-b5. On the other hand, the protein obtained after trypsin action, which eliminates an hydrophobic peptide of about 54 residues, is called cytochrome t-b5. Fluorescence polarization of the dansyl phosphatidylethanolamine probe inserted into phospholipid vesicles is very sensitive to the binding of proteins, and so is a useful method to study lipid-protein interactions. The chromophore mobility, R, decreases markedly when dipalmitoyl phosphatidylcholine vesicles are incubated with cytochrome d-b5, whereas R does not change for cytochrome c and cytochrome t-b5. This can be interpreted as a strengthening of bilayer, only due to the interaction of the hydrophobic peptide tail. Interaction of dipalmitoly phosphatidylcholine vesicles with cytochrome d-b5 occurs either below or above the melting temperature of the aliphatic chains (41 degrees C). Even for a high protein to lipid molar ratio (1 molecule of protein for 40 phospholipid molecules), the melting temperature is apparently unaffected. Phosphatidylserine and phosphatidylinositol do not interact at pH 7.7 with cytochrome d-b5, because electrostatic forces prevent formation of complexes. At low pH, the interaction with the protein occurs, but the binding is mainly of electrostatic nature.
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PMID:Lipid-protein interactions in membrane models. Fluorescence polarization study of cytochrome b5-phospholipids complexes. 0 65

The photosensitive inactivation of trypsin and chymotrypsin by 4-fluoro-3-nitrophenyl azide (FNPA) is described. A dark inhibition was observed at elevated probe concentrations, and was reversible. The enzymes were stable to photolysis in the absence of probe. Photolytic inactivation of trypsin and chymotrypsin with FNPA was found to be irreversible, and occurs in minutes at concentrations of FNPA where dark inhibition is negligible. The photoprobe was equally effective at pH 3 or pH 8. Nonspecific inactivation appears to be low, as evidenced by the stability of glucose oxidase and peroxidase to photolysis with FNPA.
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PMID:Inactivation of trypsin and chymotrypsin with a photosensitive probe. 0 98

Supernatant fluids from murine spleen cell cultures incubated with concanavalin A for 48 hr contain a factor(s), soluble immune response suppressor (SIRS), which suppresses plaque-forming cell responses to sheep erythrocytes by murine spleen cells in vitro. In the present studies, some of the biochemical and biophysical properties of SIRS were investigated. SIRS was non-dialysable; the suppressive activity was stable at 56 degrees C for 30 min, but was destroyed by treatment at 70 degrees C for 30 min, 80 degrees C for 10 min, or at pH 2. The suppressive activity was not absorbed by the stimulating antigen, SRBC, or antisera against murine IgG or mu-chain, suggesting that SIRS does not contain immunoglobulin determinants. Murine spleen and thymus, but not kidney cells, however, absorbed SIRS activity. Enzyme treatments revealed that SIRS was resistant to DNase and RNase, but was destroyed by trypsin and chymotrypsin. In gel filtration with Sephadex G-100, SIRS activity eluted in the fraction corresponding to m.w. in the range between 48,000 and 67,000. With polyacrylamide gel electrophoresis, SIRS activity migrated in the region cathodal to albumin. Isopycnic centrifugation in a cesium chloride gradient suggested that SIRS is a glycoprotein. These supernatant fluids with SIRS activity were also found to contain macrophage migration inhibitory factor (MIF). In the experiments using gel filtration, polyacrylamide gel electrophoresis, and isopycnic centrifugation to fractionate supernatant fluids, SIRS and MIF activity were found in the same fractions, and to date we have been unable to dissociate definitively SIRS activity from MIF activity.
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PMID:Biological expressions of lymphocyte activation. V. Characterization of a soluble immune response suppressor (SIRS) produced by concanavalin A-activated spleen cells. 0 95


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