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)

The Brassica napus cDNA clone A9 and the corresponding Arabidopsis thaliana gene have been sequenced. The B. napus cDNA and the A. thaliana gene encode proteins that are 73% identical and are predicted to be 10.3 kDa and 11.6 kDa in size respectively. Fusions of an RNase gene and the reporter gene beta-glucuronidase to the A. thaliana A9 promoter demonstrated that in tobacco the A9 promoter is active solely in tapetal cells. Promoter activity is first detectable in anthers prior to sporogenous cell meiosis and ceases during microspore premitotic interphase. The deduced A9 protein sequence has a pattern of cysteine residues that is present in a superfamily of seed plant proteins which contains seed storage proteins and several protease and alpha-amylase inhibitors.
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PMID:The isolation and characterisation of the tapetum-specific Arabidopsis thaliana A9 gene. 162 74

A monoclonal antibody (2C5) raised against rat liver lysosomal membranes was used to identify a 78-kD glycoprotein that is present in the membranes of both endosomes and lysosomes and, therefore, is designated endolyn-78. In cultures of rat hepatoma (Fu5C8) and kidney cells (NRK), this glycoprotein could not be labeled with [35S]methionine or with [32P]inorganic phosphate but was easily labeled with [35S]cysteine and [3H]mannose. Pulse-chase experiments and determinations of endoglycosidase H (endo H) sensitivity showed that endolyn-78 is derived from a precursor of Mr 58-62 kD that is processed to the mature form with a t1/2 of 15-30 min. The protein has a 22-kD polypeptide backbone that is detected after a brief pulse in tunicamycin-treated cells. During a chase in the presence of the drug, this is converted into an O-glycosylated product of 46 kD that despite the absence of N-linked oligosaccharides is effectively transferred to lysosomes. This demonstrates that the delivery of endolyn-78 to this organelle is not mediated by the mannose-6-phosphate receptor (MPR). Immunocytochemical experiments showed that endolyn-78 is present in the limiting membranes and the interior membranous structures of morphologically identifiable secondary lysosomes that contain the lysosomal hydrolase beta-glucuronidase, lack the MPR, and could not be labeled with alpha-2-macroglobulin at 18.5 degrees C, a temperature which prevents appearance of endocytosed markers in lysosomes. Endolyn-78 was present at low levels in the plasma membrane and in peripheral tubular endosomes, but was prominent in morphologically diverse components of the endosomal compartment (vacuolar endosomes and various types of multivesicular bodies) which acquired alpha-2-macroglobulin at 18.5 degrees C, and frequently contained substantial levels of the MPR and variable levels of beta-glucuronidase. On the other hand, the MPR was very rarely found in endolyn-containing structures that were not labeled with alpha-2-macroglobulin at the low temperature. Thus, the process of lysosomal maturation appears to involve the progressive delivery of lysosomal enzymes to various types of endosomes that may have already received some of the lysosomal membrane proteins. Although endolyn-78 would be one of the proteins added early to endosomes, other lysosomal membrane proteins may be added only to multivesicular endosomes that represent very advanced stages of maturation.
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PMID:Endolyn-78, a membrane glycoprotein present in morphologically diverse components of the endosomal and lysosomal compartments: implications for lysosome biogenesis. 265 37

Activities of a cathepsin B-like cysteine proteinase have previously been observed to correlate with the malignancy of several animal and human tumors. Plasma membrane fractions of some of these tumors have been found to be enriched in cathepsin B-like activity. We have determined the subcellular distribution of this enzyme and three additional lysosomal hydrolases (cathepsin H, beta-hexosaminidase, and beta-glucuronidase) in normal murine liver and six metastatic variants of the B16 melanoma. The tissues were fractionated initially by differential centrifugation followed by Percoll density gradient centrifugation of the light mitochondrial fraction. Two fractions were obtained: an L-2 fraction enriched in all four lysosomal hydrolases; and an L-1 fraction enriched in a marker enzyme for the plasma membrane. Cathepsin B-like and beta-hexosaminidase activities, but not the other hydrolase activities, were also found to be enriched in the L-1 fractions of the metastatic B16 tumors. We explored the nature of the association of the cathepsin B-like activity with the plasma membrane using fractions from the spontaneously metastatic B16 amelanotic melanoma. Activity could not be dissociated from the plasma membrane fraction by washing with a physiological salt solution suggesting that it was not adsorbed to this fraction nonspecifically, nor could it be displaced by mannose 6-phosphate or other sugars which compete for binding to the known lysosomal receptors. High salt concentrations, low concentrations of the mild detergent saponin, mild acidification, or phosphatidylinositol-specific phospholipase C did not elute the cathepsin B-like activity. However, activity was eluted by exposure to 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate, a detergent used in the purification of integral membrane proteins. The B16 amelanotic melanoma plasma membrane-associated cathepsin B-like activity had a slightly higher pH optimum and was resistant to inactivation by neutral pH and to inhibition by three low molecular weight inhibitors of cysteine proteinases. The Ki values for inhibition by leupeptin and stefin A were 20-fold higher. The presence of a cathepsin B-like cysteine proteinase at the surface of metastatic tumor cells, particularly in a form which can retain activity at physiological pH and retain activity in the presence of extracellular proteinase inhibitors, may contribute to the focal dissolution of the extracellular matrix observed at sites of contact with invading tumor cells.
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PMID:Properties of a plasma membrane-associated cathepsin B-like cysteine proteinase in metastatic B16 melanoma variants. 282 39

Rats, germfree and conventional, were dosed with 14C-labelled benzo[a]pyrene. Faeces and urine were collected. Metabolites in faeces were effectively extracted with a new method using a combination of solvents and solid sorbents. Metabolites in urine were extracted with octadecylsilane-bonded silica. The metabolites were fractionated into groups by chromatography on a cation exchanger (SP-LH-20 or SP-Sephadex C-25) and an anion exchanger (TEAP-LH-20). Some of the groups were further purified by column chromatography and analysed by HPLC and TLC. The analyses show a complex pattern of metabolism. A large part of the metabolites (9-24% depending on animal type and route of excretion) had amphoteric properties, e.g. like glutathione and cysteine conjugates. The abundance of conjugates sensitive to beta-glucuronidase and sulphatase was low. The relative amount of acidic conjugates in faeces was much higher in the germfree than in the conventional rats indicating the influence of the intestinal flora on the metabolism. The results support the view that the mercapturic acid pathway is a quantitatively important metabolic route for benzo[a]pyrene in rats. The methods of extraction and group fractionation were designed to be generally applicable to the analysis of lipophilic xenobiotics and their metabolites.
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PMID:Studies on the chromatographic fractionation of metabolites of benzo[a]pyrene in faeces and urine from germfree and conventional rats. 350 18

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

GAM broth was cultured for 5 days at 37 degrees C to obtain maximum yields of extracellular beta-glucuronidase from smooth colonies of Clostridium perfringens (Hobbs' type 4) isolated from the feces of a patient. A crude enzyme preparation was obtained by 20-80% ammonium sulfate precipitation of the broth. The beta-glucuronidase was purified using DEAE cellulose column chromatography, gel filtration on Sephadex G-200, and affinity chromatography on Sepharose 4B-bound glucuronolactone. We obtained two kinds of beta-glucuronidase. Properties of the purified beta-glucuronidase I were an optimum pH of 7.2, a pH stability range below 7.0, and a molecular weight of 115,000. The purified beta-glucuronidase II had an optimum pH of 6.0, pH stability at around 6.0, and a molecular weight of 195,000. Cu++ and Hg++ were strong inhibitors, which inhibition was restored by cysteine. EDTA did not influence enzyme activity. The Michaelis constants of beta-glucuronidase I and beta-glucuronidase II for p-nitrophenyl glucuronide were 1.25 X 10(-3) M and 4.17 X 10(-4) M, for naphthol AS-BI glucuronide 1.35 X 10(-4) M and 1.14 X 10(-4) M, and for phenolphthalein glucuronide 7.46 X 10(-5) M and 2.50 X 10(-4) M.
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PMID:Beta-glucuronidases of clostridium perfringens. 609 66

The excretion and biliary metabolites of intravenously administered benzo[a]pyrene 4,5-oxide were studied in the rat at two dose levels. After administration of 4.5 or 0.47 mumol, half of the dose was excreted in the bile in 60 min. Biliary metabolites were separated by reverse-phase high-pressure liquid chromatography and identified by cochromatography with biosynthetic standards, beta-glucuronidase hydrolysis, ultraviolet spectrophotometry and, in the case of the thioether conjugates, identification of the constituent amino acids. The major biliary metabolite was a mixture of isomeric glutathione conjugates. Some cysteine conjugate was also present, but no cysteinylglycine conjugate was detected. Hydration to transbenzo[a]pyrene-4,5-dihydrodiol followed by glucuronidation was also a quantitatively important metabolic pathway. Although benzo[a]pyrene-4,5-dihydrodiol glucuronide was more readily excreted by the liver than was benzo[a]pyrene 4,5-oxide:glutathione conjugate, the rate of glucuronidation of the dihydrodiol was low, resulting in its accumulation in the liver and possible release into the circulation. Therefore, the glutathione S-transferases may provide a more efficient mechanism for the removal of benzo[a]pyrene 4,5-oxide from the body than is provided by expoxide hydrolase.
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PMID:Metabolism and biliary excretion of benzo[a]pyrene 4,5-oxide in the rat. 610 90

Human seminal plasma contain two forms of beta-glucuronidase (beta-D-glucuronidase glucuronosohydrolase, EC 3.2.1.31) which are present in the ratio of 4:1. The major form of beta-glucuronidase with a slow moving band in electrophoresis was purified to homogeneity as revealed by polyacrylamide gel electrophoresis, double immunodiffusion and immunoelectrophoresis. The major form of beta-glucuronidase shows dual optimum pH at 4.3 and 4.7 with a dip in the activity at pH 4.5. The Km of this form of beta-glucuronidase is dependent on pH and was found to be 0.95, 3.08 and 0.67 mM at pH 4.4, 4.5 and 4.7, respectively. The major form of beta-glucuronidase from seminal plasma is stable at 55 degrees C for 30 min but it denatures at 65 degrees C. Heat denaturation is faster at acidic pH (4.7) than at alkaline pH (7.8). However, the activity of enzyme increased linearly with increase in temperature up to 70 degrees C during incubation with substrate. Cu, Ag, Hg and Ni salts inhibited enzyme activity significantly at 0.1 and 1.0 mM concentration, but the inhibition of HgCl2 was protected by cysteine. 1,4-D-Saccharic acid lactone and ascorbic acid inhibited seminal beta-glucuronidase competitively, yielding Ki values of 1.7 . 10(-3) mM and 10.3 mM, respectively. Though fructose and mannose also showed significant inhibition of beta-glucuronidase at 10-100 mM, glucose did not show any effect. The molecular weight of the major form of beta-glucuronidase was found to be 279 000, and it appears to be composed of four subunits each having a molecular weight of 74 000.
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PMID:Isolation and characterization of the major form of beta-glucuronidase from human seminal plasma. 641 96

In this study, an effect of single administration of organic thio-compounds on the combined use with uridine diphosphate glucuronic acid was investigated. In the single administration of organic thio-compounds to Wistar strain rats, the synthesis of glucuronide was slightly accelerated by glutathione or methionine, but it was not so much as in the single administration of UDPGA. The glucuronyltransferase activity was accelerated, when either taurine or methionine was administered in combination with UDPGA. None of these organic thio-compounds used in this study showed more significant inhibitory action of beta-glucuronidase activity than UDPGA in the single administration. It was perceived, however that the inhibitory action of beta-glucuronidase activity was much accelerated, when UDPGA was administered in combination either with taurine or methionine. In the administration of organic thio-compounds to Gunn strain rats, cysteine was detected to be the compound which accelerated the synthesis of glucuronide. It was also noted that no organic thio-compounds used in this study affected as influence on beta-glucuronidase activity.
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PMID:Effect of organic thio-compounds on detoxication of glucuronyltransferase and beta-glucuronidase in the rat liver. 679 Jul 25

Amino acid analysis of oxidized or reduced and carboxymethylated beta-glucuronidase have shown the presence of 24 cysteic acid or S-carboxymethylcysteine residues respectively per mole of the tetrameric enzyme. Titration of sulfhydryl groups gave eight cysteine residues, and by difference 16 half-cystine residues per mole. Six peptides containing radiolabelled cysteine residues were isolated from pepsin and chymotrypsin digest of reduced and S-carboxymethylated beta-glucuronidase by ion-exchange chromatography or gel filtration, followed by paper ionophoresis and paper chromatography. The peptides were analysed for amino acids and sequenced by the dansyl-Edman procedure. Peptides containing cysteic acid were selectively recovered from thermolysin digests of performic acid-oxidized glucuronidase. The amino acid sequences confirmed that there were only six different peptide sequences containing either cysteine or half-cystine residues in the tetrameric enzyme, supporting the presence of four identical subunits. These sequences wer: (A)-Val-Asx-Val-Ile-Cys-Val-Asx-Ser-Tyr- (B)-Gly-Asx-Leu-Cys-Ser-Gly- (C)-Phe-Val-Val-Ile-Asx-Glx-Cys-Pro-Gly-Val-Gly- (D)-Val-Val-Cys-Leu- (E)-Gln-Ser-Gly-Cys-Leu-Val-Lys-Gly-Tyr- (F)-Cys-Asp-Arg-Tyr-Gly-Ile-Val-Val-.
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PMID:Amino acid sequences containing cysteine or half-cystine residues in beta-glucuronidase. 721 58


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