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:3.2.1.31 (beta-glucuronidase)
7,680 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

N-Acetyl-beta-hexosaminidase, beta-galactosidase and beta-glucuronidase activities were shown to be present in cultured rabbit articular chondrocytes. Secretion of enzyme activity seems to preferentially result in the accumulation of N-acetyl-beta-hexosaminidase. Three days after seeding, the amount of N-acetyl-beta-hexosaminidase activity found in the medium accounts for about 140% of the total N-acetyl-beta-hexosaminidase activity after complete disruption of the cell pellet. Optimal conditions of incubation time, cell numbers, substrate concentration, and pH for glycosidase activities were determined in 0.1% Triton X-100. Intracellular and secreted glycosidases have shown similar elution profiles by chromatofocusing. N-acetyl-beta-hexosaminidase exhibits two major forms which may play a role in the catabolism of glycosaminoglycans.
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PMID:Partial characterization of intracellular and secreted glycosidases from rabbit articular chondrocytes in culture. 311 49

Homogenates of Giardia lamblia trophozoites exhibited the following hydrolase activities: acid phosphatase (EC 3.1.3.2), proteinase (EC 3.1.4) with urea-denatured hemoglobin and N-benzoyl-DL-arginine-2-naphthylamide as substrates, deoxyribonuclease (EC 3.1.4.5), and ribonuclease (EC 2.7.7.16). beta-N-Acetylglucosaminidase (EC 3.2.1.30), beta-galactosidase (EC 3.2.1.23), beta-glucuronidase (EC 3.2.1.31), alpha-D-glucosidase (EC 3.2.1.20), beta-D-glucosidase (EC 3.2.1.21), and beta-D-xylosidase (EC 3.2.1.37) activities were below the level of detection. Differential and isopycnic centrifugation of homogenates demonstrated that giardial hydrolases were localized in a single-particle population sedimenting at 7200g for 30 min. The particles had a buoyant density in sucrose of 1.15 and exhibited latency. Latency was completely destroyed by Triton X-100 or 15 cycles of freezing and thawing. After centrifugation of Triton- or freeze-thaw-treated particle fractions, the hydrolase activities, though no longer latent, were still sedimentable suggesting tight binding to the organelle membrane. Latency was destroyed simultaneously for all hydrolases, in direct proportion to the amount of Triton added to a particle preparation or to the number of times a particle preparation was subjected to freezing and thawing. These results support the suggestion that the hydrolases of G. lamblia trophozoites are localized in a single-particle population of lysosome-like organelles.
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PMID:Giardia lamblia: localization of hydrolase activities in lysosome-like organelles of trophozoites. 327 50

The effects of zinc acexamate on stress and reserpine ulcers as well as on gastric mast cells degranulation and membrane stability were evaluated in the rat. Zinc acexamate (100 mg/kg) has demonstrated an inhibitory effect on cold-restraint stress and reserpine-induced ulcer in a dose-dependent manner. Pretreatment of rats, prior to cold restraint stress, reduced gastric mast cell degranulation. Zinc acexamate (10(-4) M) inhibits Triton X-100 release of beta-glucuronidase in isolated hepatic lysosomes. These observations suggest that ulcer protective actions of zinc acexamate may be exerted in part through enhancing gastric mucosal resistance by stabilizing biological membrane integrity.
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PMID:Anti-ulcer and membrane stabilizing actions of zinc acexamate. 357 22

A receptor which recognizes glycoproteins bearing terminal mannose residues has been isolated from human placental membranes. Washed membranes were solubilized with buffer containing 1% Triton X-100 and applied to a mannose-Sepharose affinity column. The column was eluted with buffer containing 200 mM mannose and 1% cholate. The major protein eluted exhibited a molecular weight of 175 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The protein binds 125I-labeled mannosylated bovine serum albumin in a saturable fashion with a dissociation constant of 4 nM. Ligand binding is pH-dependent with maximal binding above pH 6.5. This binding can be inhibited with EDTA, mannose, fucose, mannan, beta-glucuronidase, and bovine serum albumin conjugated to fucose. Polyclonal antibodies generated against the mannose binding protein immunoprecipitate a single 175-kDa protein species from both surface-iodinated and biosynthetically labeled human monocyte-derived macrophages.
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PMID:Isolation and characterization of a mannose-specific endocytosis receptor from human placenta. 361 Oct 70

Rabbit alveolar macrophages express a plasma-membrane receptor that recognizes glycoprotein ligands bearing terminal mannose, fucose or N-acetylglucosamine residues. Macrophage membranes were washed extensively with buffers containing high salt and mannose or EDTA to remove endogenously bound ligand, before Triton X-100 extraction. The extracts were chromatographed on mannose-Sepharose. Elution with mannose, followed by dialysis and a second mannose-Sepharose step with EDTA elution, produced a preparation that migrated as single protein band of Mr 175,000 on SDS/polyacrylamide-gel electrophoresis. The purified protein binds mannose-BSA (bovine serum albumin) with a dissociation constant of 1.9 X 10(-8) M. Ligand binding is Ca2+ and pH-dependent, with maximal binding at neutral pH and low binding below pH 6.0. The binding of 125I-mannose-BSA is inhibited by ligands bearing high-mannose oligosaccharides, such as mannan or beta-glucuronidase, as well as the monosaccharides mannose, fucose and N-acetylglucosamine. Galactose, galactosylated BSA, glucose and mannose 6-phosphate are non-inhibitory. Amino acid compositional analyses indicate that the receptor contains high concentrations of aspartate/asparagine and glutamate/glutamine, and low amounts of methionine. The carbohydrate composition was studied by lectin overlays of electrophoretically transferred receptor, and the results indicate the presence of N-linked complex and O-linked sialylated oligosaccharides. A protein of Mr 175,000 was immunoprecipitated from radio-iodinated macrophage membranes with an antibody generated against purified rabbit lung mannose receptor.
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PMID:Isolation and characterization of a mannose-specific endocytosis receptor from rabbit alveolar macrophages. 366 87

Mouse liver beta-glucuronidase is stabilized within microsomal vesicles by complexation with the accessory protein egasyn. The location of the beta-glucuronidase-egasyn complex and free egasyn within microsomal vesicles was investigated. Surprisingly, it was found that neither the complex nor free egasyn are intrinsic membrane components. Rather, both are either free within the vesicle lumen or only weakly bound to the inside of the vesicle membrane. This conclusion was derived from release studies using low concentrations of Triton X-100 or controlled sonication. Both the intact complex and free egasyn were released in parallel with lumenal proteins, not with intrinsic membrane components. Also, beta-glucuronidase was protected from digestion by proteinase K by the membrane of microsomal vesicles. The hydrophilic nature of both the complex and free egasyn was confirmed by phase separation experiments with the detergent Triton X-114. Egasyn is one of an unusual group of esterases that, despite being located within the lumen or only weakly bound to the lumenal surface of the endoplasmic reticulum, do not enter the secretory pathway.
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PMID:Lumenal location of the microsomal beta-glucuronidase-egasyn complex. 366 91

Lysosomal membrane fractions were prepared from lysosomes of mouse liver by freeze-thawing in a hypotonic buffer: 54% of beta-glucosidase [EC 3.2.1.45] in lysosomes was associated with the membrane fractions, whereas 96% of beta-glucuronidase [EC 3.2.1.31] was recovered in the soluble fractions of lysosomes. beta-glucosidase was solubilized by pH 9.5 treatment or by Triton treatment of membranes. The enzyme solubilized with alkali and concentrated with (NH4)2SO4 was rapidly inactivated in a solution of pH 9.5, but could be protected against inactivation by acidic detergent. Gel filtration analysis indicated that beta-glucosidase was in an aggregated form at neutral pH and could be disaggregated by alkali and detergents. The enzyme dissociated with detergents also showed a higher activity than the alkali-treated enzyme. These results suggested that beta-glucosidase is a peripheral enzyme bound to acidic lipids in membranes. beta-Glucosidase was purified to apparent homogeneity by (NH4)2SO4 fractionation and chromatographies with Sephacryl S-300, hydroxylapatite and cation exchangers in the presence of detergents. The catalytic activity of the purified enzyme was maximally stimulated by phosphatidylserine and heat-stable protein in the presence of a low concentration of Triton X-100. The stimulation was mainly due to an increase in Vmax.
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PMID:Characterization of beta-glucosidase as a peripheral enzyme of lysosomal membranes from mouse liver and purification. 393 51

A method for the isolation of intact phagocytic vesicles from guinea pig peritoneal-exudate granulocytes and human peripheral-blood leukocytes is presented. After leukocytes ingested the particles of a stable emulsion of paraffin oil, the uningested emulsion was washed away and the cells were homogenized. The homogenate was placed in the middle of a three-step discontinuous sucrose gradient and centrifuged for 1 hr at 100,000 g. The phagocytic vesicles, containing the low density paraffin-oil particles, were simultaneously washed and collected by floatation, while the other organelles, chiefly granules, sedimented through the lower wash layer, and the particle-free supernatant remained in the middle of the gradient. Emulsion particles stained with Oil Red O were employed to assay the rate of phagocytosis and to mark the location of the particles in subcellular fractions. The dye was extracted from washed cells or cell fractions with dioxane and colorimetrically quantified. The purity of phagocytic vesicles obtained by this method was assessed by electron microscopy, chemical analysis, and assay of enzyme composition. Granule-associated enzymes, acid phosphatase, alkaline phosphatase, beta-glucuronidase, and peroxidase were present in the phagocytic vesicles and originated from the granules. Cyanide-resistant NADH (reduced form of diphosphopyridine nucleotide) oxidase was also found. Enzymes associated with the vesicles exhibited latency to Triton X-100. Uptake of particles and the transfer of total protein and phospholipid into phagocytic vesicles occurred simultaneously Accumulation of acid and alkaline phosphatase in the vesicles continued until phagocytosis ceased. Peroxidase, NADH oxidase, and beta-glucuronidase activities in the phagocytic vesicles, on the other hand, were maximal by 30 min and increased little thereafter even when phagocytosis was still going on.
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PMID:Isolation and properties of phagocytic vesicles from polymorphonuclear leukocytes. 410 63

In order to study mechanisms underlying selective enzyme release from human leukocytes during phagocytosis, the effects were studied of compounds which affect microtubule integrity or the accumulation of cyclic nucleotides. Human leukocytes selectively extrude lysosomal enzymes (beta-glucuronidase) from viable cells during phagocytosis of zymosan or immune complexes, or upon encounter with immune complexes dispersed along a non-phagocytosable surface such as a millipore filter. In each circumstance, lysosomal enzyme release was reduced by previous treatment of cells with pharmacological doses of drugs which disrupt microtubules (e.g. 10(-3)-10(-5) M colchicine) or with agents which affect accumulation of adenosine 3'5'-monophosphate (cAMP) (e.g. 10(-3) M cyclic nucleotides and 2.8 x 10(-4)-2.8 x 10(-6) M prostaglandin E (PGE) and A (PGA) compounds). Preincubation of cells with 5 microg/ml cytochalasin B resulted in complete inhibition of zymosan ingestion, but not of adherence of zymosan particles to plasma membranes or selective enzyme release. In this system, in which enzyme release was independent of particle uptake, preincubation of cells with colchicine, vinblastine, dibutyryl cAMP, or PGE(1) also reduced extrusion of lysosomal enzymes. When cell suspensions were incubated with membrane-lytic crystals of monosodium urate (MSU), cytoplasmic as well as lysosomal enzymes were released with subsequent death of the cells. However, enzyme release followed phagocytosis of crystals (as measured by enhanced C-1 oxidation of glucose) and was due to "perforation from within" of the lysosomal membrane, rather than lysis by crystals of the plasma membrane. Enzyme release after MSU ingestion was also reduced when cells were treated with pharmacological doses of the test agents. When cells were killed by Triton X-100, acting on the plasma membrane, C-1 oxidation of glucose was abolished and enzyme release could not be inhibited pharmacologically. These observations suggest that lysosomal enzyme release from human phagocytes can be an active process which accompanies plasma membrane stimulation, is independent of cell death, and may be controlled by cyclic nucleotides and agents which affect microtubules.
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PMID:Mechanisms of lysosomal enzyme release from human leukocytes. I. Effect of cyclic nucleotides and colchicine. 412 73

1. A partially purified lysosomal preparation was obtained from adult mouse livers by sucrose-density-gradient centrifugation of a large-granule fraction. 2. This lysosome-enriched subfraction was contaminated approx. 10% by mitochondrial cytochrome c oxidase and malate dehydrogenase. 3. Free acid phosphohydrolase and beta-glucuronidase contributed less than 10% of the total (Triton X-100-solubilized) activity in contrast with approx. 30% free N-acetyl-beta-d-glucosaminidase when assayed in an iso-osmotic incubation system. 4. Exposure of the lysosomal preparation to inorganic Hg(2+) ions and organic mercurials (p-chloromercuribenzoate, phenylmercuric acetate) induced an irreversible loss of structure-linked latency with resulting enzyme activation. 5. Maximal activation was related to log [Hg(2+)] and pH. The response was all-or-none for individual particles; the dose-response curve portrayed the variation in particle resistance within the lysosomal population. 6. l-Cysteine and GSH totally prevented Hg(2+) ion-induced hydrolase activation. Ascorbate provided approx. 50% protection. 7. The three lysosomal hydrolases were differentially activated at constant [Hg(2+)], suggesting a different pattern of binding, unique for each enzyme studied.
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PMID:Effect of mercurial compounds on structure-linked latency of lysosomal hydrolases. 429 23


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