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)

A protease zymogen present in the plasma fraction of the hemolymph of silkworm, Bombyx mori, was purified to homogeneity as judged by SDS/PAGE and IEF/PAGE. An activating system for the zymogen was also isolated from the plasma fraction and was shown to be triggered by zymosan (yeast cell wall polysaccharide containing beta-1,3-glucan) or peptidoglycan. Using this system, the purified zymogen was activated and the active enzyme was purified to homogeneity. The physiological function of the zymogen or its active form is not yet known, but the active form was shown to have narrower substrate specificity than trypsin. Among 33 peptide derivatives examined, Boc-Gln-Arg-Arg-NH-Mec and Boc-Val-Pro-Arg-NH-Mec (Boc = tert-butoxycarbonyl, NH-Mec = 4-methylcoumaryl-7-amide) were the best and the second best substrates, respectively. The purified zymogen was determined to be a 39-kDa protein consisting of a single polypeptide. The active form of the zymogen was labeled with [3H]diisopropylfluorophosphate and was completely inactivated by (p-amidinophenyl)methanesulfonyl fluoride. The molecular mass of the [3H]-labeled enzyme was determined to be 38 kDa in SDS/PAGE under reducing conditions. These results indicate that the 39-kDa protein purified in the present study is a zymogen of a serine-type protease and that the activation of the zymogen occurs by limited proteolysis.
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PMID:A serine protease zymogen in insect plasma. Purification and activation by microbial cell wall components. 773 88

An inhibitor of Streptococcus sobrinus endodextranase was detected in the extracellular fractions of UAB66 mutants identified following ethyl methanesulfonate mutagenesis as either devoid of dextranase activity (Dex-) or overproducing water-soluble glucan. The two groups of mutants had the same phenotype and displayed no dextranase activity in assays of extracellular fractions (H. Murchison, S. Larrimore, and R. Curtiss III, Infect. Immun. 34:1044-1055, 1981) and had been shown to be defective in adherence (Adh-) and capable of inhibiting adherence of wild-type strains during cocultivation in vitro (H. Murchison, S. Larrimore, and R. Curtiss III, Infect. Immun. 50:826-832, 1985) and in vivo in gnotobiotic rats (K. Takada, T. Shiota, R. Curtiss III, and S. M. Michalek, Infect. Immun. 50:833-843, 1985). By analysis of proteins in Western blots (immunoblots) and following blue dextran-sodium dodecyl sulfate-polyacrylamide gel electrophoresis (BD-SDS-PAGE), it was demonstrated that these Dex- mutants did synthesize enzymatically active dextranase. From the results of mixing experiments, it was determined that these Dex- Adh- mutants produced enhanced amounts of a cell surface-localized or a cell-associated dextranase inhibitor (Dei). Dei was heat stable but trypsin sensitive. By adding excess dextranase following BD-SDS-PAGE, Dei was detected as blue bands with apparent molecular masses of 43, 40, 37, 27, and 23 kDa. Dei competitively inhibits dextranase activity and is synthesized by wild-type S. sobrinus strains, with the amount varying depending upon growth medium and stage in the growth cycle. R. M. Hamelik and M. M. McCabe (Biochem. Biophys. Res. Commun. 106:875-880, 1982) previously described a Dei in a wild-type S. sobrinus strain.
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PMID:Overproduction of a dextranase inhibitor by Streptococcus sobrinus mutants. 796 92

In mice and humans zymosan binds to the complement receptor three/Mac-1 receptor; however, identification of this receptor in channel catfish (Ictalurus punctatus) has not been accomplished. Soluble fluorescein isothiocyanate (FITC) conjugated beta-glucan, a component of zymosan, was found to bind to channel catfish anterior kidney (AK) neutrophils but not to B-lymphocytes. Serum activated zymosan (SAZ)-mediated chemiluminescence responses of channel catfish AK neutrophils could be inhibited by beta-glucan but not by mannan, and inhibition of chemiluminescence responses by beta-glucan was dose dependent. Similarly, phagocytosis of FITC-SAZ could be inhibited by beta-glucan in a dose-dependent manner. Treatment of channel catfish AK neutrophils with various concentrations of trypsin resulted in inhibition of phagocytosis of FITC-SAZ but not of Aeromonas hydrophila indicating that A. hydrophila phagocytosis was mediated by a trypsin-resistant receptor. Deleting serum or using heat-inactivated serum in the mixtures for the chemiluminescence and FITC-SAZ phagocytosis assays resulted in baseline readings. These data indicate that the beta-glucan component of zymosan is responsible for zymosan phagocytosis. Furthermore, the recognition of zymosan by a specific receptor is evident based on trypsin sensitivity assays. Based on these results it is proposed that a complement receptor 3, Mac-1-like receptor, is present on channel catfish AK neutrophils.
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PMID:A beta-glucan inhibitable zymosan receptor on channel catfish neutrophils. 806 90

Previous studies have established the efficacy of soluble polymers of poly-(1-6)-beta-glucotriosyl-(1-3)-beta-glucopyranose (PGG) glucan, a biological-response modifier, in protecting against mortality associated with experimentally induced peritonitis in a rat model. PGG glucan-treated animals showed increases in total leukocyte counts and enhanced bacterial clearance from blood. To further explore the mechanisms) by which this agent confers protection, studies were performed to examine whether protection could be transferred from PGG glucan-treated animals to naive recipients via spleen cells (SC), SC lysates, or serum. Passive-transfer experiments indicated that the responsible factor(s) was transferable by whole SC and SC lysates, as well as by peripheral leukocytes or serum from animals treated with PGG glucan. The transferable factor(s) was resistant to pronase and trypsin digestion, was heat stable at 56 or 80 degrees C, and was not removed by NH4SO4 precipitation. The protective effect of PGG glucan was abrogated by treatment with indomethacin, a potent inhibitor of prostaglandin synthesis. Administration of a purified prostaglandin extract from the sera of PGG glucan-treated animals protected against mortality in the peritonitis model. Furthermore, treatment of rats with exogenous synthetic prostaglandin E2 also conferred protection against mortality. These results suggest that the protective effect exhibited by PGG glucan in the rat peritonitis model is mediated, at least in part, by prostaglandins.
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PMID:Passive transfer of poly-(1-6)-beta-glucotriosyl-(1-3)-beta-glucopyranose glucan protection against lethal infection in an animal model of intra-abdominal sepsis. 867 27

Phenoloxidase activity was detected in plasma and haemocytes of the marine mussel Perna viridis. This enzyme exists as a proenzyme, prophenoloxidase (proPO), in both these haemolymph fractions and could be activated in vitro by exogenous proteases (trypsin and alpha-chymotrypsin) and a detergent (sodium dodecyl sulphate). In addition, laminarin (a polymer of beta-1,3 glucan) and bacterial lipopolysaccharides (LPSa) effectively triggered proPO activation in these haemolymph fractions. The activation of proPO by non-self molecules was dependent upon calcium ions at a low concentration. This activation process appeared to involve a limited proteolysis, since serine protease inhibitors (soybean trypsin inhibitor, benzamidine or p-nitrophenyl-p'-guanidinobenzoate) suppressed conversion of proPO to the active enzyme. This study demonstrates the selective response of plasma and haemocytic proPO to activation by different types of bacterial LPS tested and suggests that proPO system in both plasma and haemocytes of P. viridis serves an important function in non-self recognition and host immune reactions.
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PMID:Activation of prophenoloxidase in the plasma and haemocytes of the marine mussel Perna viridis Linnaeus. 924 84

In pollen tubes of Nicotiana alata, a membrane-bound, Ca(2+)-independent callose synthase (CalS) is responsible for the biosynthesis of the (1,3)-beta-glucan backbone of callose, the main cell wall component. Digitonin increases CalS activity 3- to 4-fold over a wide range of concentrations, increasing the maximum initial velocity without altering the Michaelis constant for UDP-glucose. The CalS activity that requires digitonin for assay (the latent CalS activity) is not inhibited by the membrane-impermeant, active site-directed reagent UDP-pyridoxal when the reaction is conducted in the absence of digitonin. This is consistent with digitonin increasing CalS activity by the permeabilization of membrane vesicles. A second group of detergents, including 3-[(3-cholamidopropyl)dimethylammonio]-1-propane-sulfonate (CHAPS), Zwittergent 3-16, and 1-alpha-lysolecithin, activate pollen tube CalS 10- to 15-fold, but only over a narrow range of concentrations just below their respective critical micellar concentrations. This activation could not be attributed to any particular chemical feature of these detergents. CHAPS increases maximum initial velocity and decreases the Michaelis constant for UDP-glucose and activates CalS even in the presence of permeabilizing concentrations of digitonin. Inhibition studies with UDP-pyridoxal indicate that activation by CHAPS occurs by recruitment of previously inactive CalS molecules to the pool of active enzyme. The activation of pollen tube CalS by these detergents therefore resembles activation of the enzyme by trypsin.
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PMID:Activation of pollen tube callose synthase by detergents. Evidence for different mechanisms of action. 927 48

The phenoloxidase (PO) activity of hemocyte lysate supernatant (HLS) from both tiger shrimp (Penaeus monodon) and giant freshwater prawn (Macro-branchium rosenbergii) was examined by treating HLS with various factors, such as an increase in temperatures from 25 to 70 degrees C, one of four elicitors (beta-1,3-1,6-glucan, zymosan, heat-killed Vibrio cells, and lipopolysaccharide), trypsin, one of three protease inhibitors (soybean trypsin inhibitor, p-nitrophenyl-p'-guanidinobenzoate, and benzamidine), and one of two divalent cations (Mg2+ and Ca2+). The strongest PO activity in both animals was induced at 37 degrees C, while enzyme activity varied according to the concentration of the elicitors or cations added to the HLS samples. The following optimum concentrations were recorded: lipopolysaccharides at 0.5 mg/ml, both beta-glucan and zymosan at 1 mg/ml, and Vibrio cells at 10(6) cells/ml. In addition, for giant freshwater prawn, PO activity increased when HLS was treated with trypsin and decreased when it was separately treated with three protease inhibitors. However, effects of either trypsin or protease inhibitors did not occur in tiger shrimp. Strongest PO activity occurred in HLS treated with 20 mM of either calcium ion or magnesium ion, and the addition of the two cations led to an increase in enzyme activity; a decrease was noted following the treatment with EDTA. Cytochemical analysis revealed that prophenoloxidase system exists in the granulocytes of both tiger shrimp and giant freshwater prawn.
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PMID:Phenoloxidase activity of hemocytes derived from Penaeus monodon and Macrobrachium rosenbergii. 944 34

We isolated glucan-binding peptides of a dextransucrase from Leuconostoc mesenteroides B-512F. The dextransucrase was bound to DEAE-Sephadex A-50, Sephadex G-100, and mutan from Streptococcus mutans. Mild trypsin digestion dissociated the enzyme and glucan binding. In the presence of ammonium sulfate, several peptides were bound to glucan after trypsin digestion. Four main mutan-binding peptides were obtained by this method, and those amino acid sequences were analyzed. One of them was identical with the dextran-binding peptide that contains lysine, which was previously isolated by differential chemical modification with o-phthalaldehyde. We also found mutan-binding peptides in sucrose- and dextran-binding regions and a lysine-rich region. Also, there was a peptide similar in sequence to glucan-binding A-repeat of streptococcal glucosyltransferases.
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PMID:Glucan binding regions of dextransucrase from Leuconostoc mesenteroides NRRL B-512F. 950 23

The extracellular material (EM) produced by the white rot fungus Phlebia radiata cultured in an N-limited liquid medium was studied. Carbohydrate analysis showed maximum concentration of glucose as the major monosaccharide component of EM was found on postinoculation day 9. Beyond day 9 of cultivation the proportion of glucose decreased suggesting that the glucan component of EM had been further metabolized. The analysis of EM at day 9 revealed the presence of the following monosaccharides (in relative %): glucose (62); galactose (16); mannose (13); xylose (4); and fucose (5). The carbohydrate analysis together with the presence of protein in EM corresponds to a mixture of glucan and glycoprotein. Purification by trypsin treatment yielded an enriched glucose-containing extracellular polysaccharide (EPS). Methylation analysis identified EPS as (1-3)-beta-D-glucan highly branched at C-6. The structure of the glucan was confirmed by 13C-NMR spectroscopy. The results suggest that P. radiata's EPS is entangled with a glycoprotein in a complex that makes the extracellular sheath surrounding the hyphae.
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PMID:Structure of extracellular polysaccharide produced by lignin-degrading fungus Phlebia radiata in liquid culture. 1007 73

Glucosyltransferase-I (GTF-I: 175 kDa) of a cariogenic bacterium, Streptococcus sobrinus 6715, mediates the conversion of water-soluble dextran (alpha-1,6-glucan) into a water-insoluble form by making numerous alpha-1,3-glucan branches along the dextran chains with sucrose as the glucosyl donor. The structures and catalytic properties were compared for two GTF-I fragments, GTF-I' (138 kDa) and GS (110 kDa). Both lack the N-terminal 84 residues of GTF-I. While GTF-I' still contains four of the six C-terminal repeats characteristic of streptococcal glucosyltransferases, GS lacks all of them. Electron microscopy of negatively stained samples indicated a double-domain structure for GTF-I', consisting of a spherical head with a smaller spherical tail, which was occasionally seen as a long extension. GS was seen just as the head portion of GTF-I'. In the absence of dextran, both fragments simply hydrolyzed sucrose with similar K(m) and k(cat) values at low concentrations (<5 mM). At higher sucrose concentrations (>10 mM), however, GTF-I' exhibited glucosyl transfer activity to form insoluble alpha-1, 3-glucans. So did GS, but less efficiently. Dextran increased the rate and efficiency of the glucosyl transfer by GTF-I'. On removal of the C-terminal repeats of GTF-I' by mild trypsin treatment, this dextran-stimulated transfer was completely lost and the dextran-independent transfer became less efficient. These results indicate that the N-terminal two-thirds of the GTF-I sequence are organized as a structurally and functionally independent domain to catalyze not only sucrose hydrolysis but also glucosyl transfer to form alpha-1,3-glucan chains, although not efficiently; the C-terminal repeat increases the efficiency of the intrinsic glucosyl transfer by the N-terminal domain as well as rendering the whole molecule primer-dependent for far more efficient insoluble glucan synthesis.
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PMID:Structure and enzymatic properties of genetically truncated forms of the water-insoluble glucan-synthesizing glucosyltransferase from Streptococcus sobrinus. 1042 19


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