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 effect of sodium taurocholate on the biliary export of stable mutagenic phenolic glucuronide metabolites of benzo(a)pyrene from livers of corn oil- or 3-methylcholanthrene-treated rats was studied using a nonrecirculating perfusion system. Sterile bile samples were collected every 4 min and assayed for mutagens using the Ames Salmonella (Ta 98) test without addition of microsomes but containing beta-glucuronidase. Rates of export of mutagens produced from benzo(a)pyrene (20 microM) into the bile were stimulated 5-fold by the bile salt sodium taurocholate, concomitant with a 2- to 3-fold increase in bile flow. Steady-state rates of 60 and 90 revertants/g/h were observed in bile when 20 microM benzo(a)pyrene was infused into livers from corn oil or 3-methylcholanthrene-treated rats, respectively. These rates of efflux were increased to 250 and 550 revertants/g/h by the addition of taurocholate. Rates of production of mutagenic phenolic metabolites which account for the mutagenic activity were determined by adding rates of efflux into bile and effluent perfusate with rates of accumulation of metabolites in the cell. In livers from 3-methylcholanthrene-treated rats, rates (8 min) of benzo(a)pyrene phenol formation averaged 300 nmol/g/h during the initial 20 min of perfusion but increased to 450 nmol/g/h after 1 h. The addition of taurocholate increased maximal rates of phenol efflux in the bile from 6 to 148 nmol/g/h and decreased rates of phenol accumulation in intracellular stores from 342 to 220. Rates of efflux into the vena cava effluent averaged 120 nmol/g/h and were not affected by taurocholate. Infusion of dehydrotaurocholate increased the appearance of metabolites of benzo(a)pyrene in the effluent perfusate but did not change rates of efflux into bile. Taurocholate doubled rates of output of phenolic metabolites into the effluent perfusate when bile flow was arrested by perfusion with calcium-free buffer. Thus, mutagenic glucuronides from benzo(a)pyrene phenols accumulated in hepatocytes much faster than rates at which they were exported. Total rates of production of phenolic glucuronides by the liver were not affected by bile salts; however, taurocholate stimulated their export into bile, while dehydrotaurocholate increased their concentration in the effluent perfusate. Both salts probably act by displacing metabolites from intracellular binding sites.
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PMID:Effect of bile salts on rates of formation, accumulation, and export of mutagenic metabolites from benzo(a)pyrene produced by the perfused rat liver. 397 30

Deuterium-labelled methadone and metabolites were used for the g.l.c.-mass spectrometry detection and identification of biliary conjugated methadone metabolites in rats. After beta-glucuronidase hydrolysis the bile extract contained an unknown metabolite that was not ring hydroxylated and retained an intact keto group. Chemical oxidation of the methadone metabolite 2-ethylidene-N,5-dimethyl-3,3-diphenylpyrrolidine, perchlorate salt (EDDP) with m-chloroperbenzoic acid in chloroform, gave a compound identical by g.l.c.-mass spectrometry to the new metabolite. The chemical oxidation product was identified as 2-(4',4'-diphenylheptan-5'-one-2'-yl)oxaziridine by spectroscopic methods. The oxaziridine was shown to quantitatively isomerize to a secondary formamide (2-formamido-4,4-diphenyl-5-heptanone) during g.l.c.-mass spectrometry analysis. The formamide was also isolated by flash column chromatography after reflux of the oxaziridine in m-xylene, and then characterized by spectroscopy. The formamide and oxaziridine g.l.c.-mass spectrometry characteristics were identical. It was concluded on the basis of g.l.c.-mass spectrometry that the metabolite is the secondary formamide.
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PMID:Methadone metabolism in the rat in vivo: identification of a novel formamide metabolite. 400 35

The granule fraction of human leukocytes contains neutral protease capable of degrading the noncollagenous protein mucopolysaccharide matrix of cartilage at neutral pH in physiological salt solution. Cartilage degradation was monitored by quantitating the release of (35)S from labeled rabbit ear cartilage. Degradation of cartilage matrix occurs when intact viable human leukocytes are incubated with cartilage opsonized with aggregated human gamma globulin (AHGG). During a similar 4 h incubation period cells did not degrade uncoated cartilage or cartilage coated with nonaggregated gamma globulin. Cells remain viable during the enzyme release process as evidenced by the absence of a cytoplasmic enzyme marker (lactic dehydrogenase) in the supernatant and dye exclusion studies. The release of (35)S from labeled cartilage by human leukocytes in the presence of cartilage coated with AHGG (nonphagocytic enzyme release) was compared with the cartilage degrading activity of the supernatant from the same number of cells preincubated with a suspension of AHGG (phagocytic enzyme release). Nonphagocytic enzyme release by 5 x 10(6) cells provoked two to four times more (35)S and beta-glucuronidase (beta-G) release from cartilage than phagocytic enzyme release conditions. beta-glucuronidase was used as an indicator of the release of lysosomal granule enzymes. By the use of selected pharmacological agents it was possible to dissociate the enzyme release process from intrinsic enzyme (neutral protease) activity. Neutral protease and beta-G release by human cells in the presence of AHGG-coated cartilage was inhibited by 10(-5)M colchicine, whereas the protease activity, but not the release process, was inhibited by 10(-6)M gold thiomalate and 10% human serum. It is suggested that the release of a cartilage degrading neutral protease by viable human cells when exposed to AHGG might be a relevant model for the study of cartilage destruction as it occurs in rheumatoid arthritis.
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PMID:Release of cartilage mucopolysaccharide-degrading neutral protease from human leukocytes. 412 11

The lysozyme content of human cartilage was measured by incubation of lyophilized, powdered cartilage in a variety of buffers and salt solutions, and the factors controlling the binding of lysozyme within cartilage were studied. Lysozyme was extracted from hyaline cartilage by buffers of pH greater than 9.0 by solutions 1 M in monovalent cations, and by solutions 0.12-0.40 M in divalent cations. The ability of cations to extract lysozyme from cartilage agreed with their known affinities for binding to chondroitin sulfate. The total extractable lysozyme content of five samples of human costal cartilage ranged from 1.45 to 3.36 mug lysozyme per mg of cartilage; for five samples of hyaline cartilage from peripheral joints the range was 0.80-3.03 mug lysozyme per mg of cartilage. Cartilage incubated in excess exogenous lysozyme could bind 0.053 equivalents of lysozyme per equivalent of chondroitin sulfate. Fibrocartilage and synovium from knee joints yielded no detectable lysozyme, despite the fact that synovium, a tissue rich in lysosomes, contained measurable quantities of beta-glucuronidase. Lysozyme extraction from cartilage was not augmented by incubation with streptolysin S. When incubation was carried out with mild extraction techniques, lysozyme extraction from cartilage tended to parallel uronic acid release, both as a function of time and from one specimen to another. The active material as lysozyme. Lysozyme occurs in human hyaline cartilage as a counterion to polyanionic glycosaminoglycans. Carextracted from cartilage met five criteria for identification tilage lysozyme appears to be extracellular and nonlysosomal. Degradation of cartilage may contribute to the increased serum and synovial fluid lysozyme levels often present in patients with rheumatoid arthritis.
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PMID:Human cartilage lysozyme. 463 12

1. Bilirubin glucuronide was synthesized in vitro in a system containing a rat liver microsomal fraction, UDP-glucuronic acid, Mg(2+) and bilirubin. The enzymic synthesis was accomplished without the addition of a bilirubin carrier. 2. Azobilirubin and azobilirubin glucuronide were separated by t.l.c. and paper chromatography and the measurement of the conjugate provided a specific assay for bilirubin UDP-glucuronyltransferase (EC 2.4.1.17). 3. This diazo compound was labelled when [U-(14)C]UDP-glucuronic acid was employed in the transglucuronidation reaction. 4. Identity of the glucuronide nature of the product was further confirmed by hydrolysis with beta-glucuronidase prepared from limpets and Helix pomatia. In each instance azobilirubin and glucuronic acid were liberated. 5. There was a close correlation between the bilirubin glucuronyl-transferase activity as measured by two procedures, colorimetric and radioisotopic. The specific activities so measured were 19nmol of bilirubin ;equivalents' conjugated/h per mg of protein and 16.9-18.4nmol of UDP-glucuronic acid incorporated/h per mg of protein, respectively. On this basis, it was concluded that the major product formed in vitro was bilirubin monoglucuronide; this represents about 77% of the total products formed. 6. The K(m) values for bilirubin and UDP-glucuronic acid at pH8.2 are 3.3x10(-4)m and 1.67x10(-3)m, respectively. 7. The addition of Mg(2+) at a final concentration of 5mm to the reaction mixture increased the rate of conjugation by 5.6-fold in the microsomal preparation that had been subjected to overnight dialysis against 10mm-EDTA (disodium salt). 8. Diethyl-nitrosamine at a final concentration of 1-20mm has no effect on the glucuronidation of bilirubin in vitro.
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PMID:Bilirubin glucuronyltransferase. Specific assay and kinetic studies. 515 13

1. The major metabolite of 2,4-dimethoxy-6-sulphanilamidopyrimidine (sulphadimethoxine) in urine in man is a non-reducing glucuronide, which has been isolated and characterized as its S-benzylthiouronium salt. 2. The same compound was made synthetically by standard methods from sodium sulphadimethoxine and methyl 2,3,4-tri-O-acetyl-1-bromoglucuronate. 3. On hydrolysis with acid, the glucuronide yielded sulphanilic acid, glucuronic acid and barbituric acid, and with beta-glucuronidase it slowly yielded sulphadimethoxine and glucuronic acid. 4. Evidence based on infrared spectra and other data showed that the urinary and synthetic glucuronide was 1-deoxy-1-[N(1)'-(2'',4''-dimethoxypyrimidin-6'' -yl)sulphanilamido-beta-d-glucosid]uronic acid or sulphadimethoxine N(1)-glucuronide. 5. N(1)-Methyl- and N(ring)-methyl derivatives of sulphadimethoxine and 4-methoxy-6-sulphanilamidopyrimidine were prepared and their infrared and ultraviolet spectra determined for comparison.
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PMID:The structure of the glucuronide of sulphadimethoxine formed in man. 586 22

Metaproterenol (1-(3,5-dihydroxyphenyl)-2-isopropylaminoethanol) is primarily converted in humans to metaproterenol-3-O-sulfate following oral administration. Ion exchange column chromatography with a gradient of ammonium acetate buffer permitted the isolation of the ammonium salt of metaproterenol-3-O-sulfate from human urine. Treatment of aliquots of the column eluate with purified sulfatase and subsequent HPLC/fluorescence analysis confirmed the presence of metaproterenol. Comparison of the column eluate with a metaproterenol standard by 250-MHz proton-NMR revealed a pattern consistent with monosubstitution of the resorcinol ring. Negative and positive ion fast atom bombardment/mass spectrometry showed the metabolite to have a (M-H)- m/z of 290 and a (M + H)+ m/z ion of 292. These three methods support the structural assignment of metaproterenol-3-O-sulfate. Enzymatic hydrolysis of urine specimens from 29 different subjects with purified beta-glucuronidase as well as beta-glucuronidase-sulfatase mixtures yielded no significant increase in metaproterenol beyond purified sulfatase-treated urine, thus ruling out the presence of a glucuronide of metaproterenol. Approximately 40% of an oral 20-mg dose, given as either a tablet or a solution, was recovered in the urine as metaproterenol-3-O-sulfate. Approximately 5% of the dose was recovered in the unconjugated form. The majority of the dose was excreted over the first 12 hr with a biological half-life of 5-6 hr followed by a slower excretion phase with a half-life of 20 hr.
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PMID:Isolation and characterization of metaproterenol-3-O-sulfate: a conjugate of metaproterenol in human urine. 614 Jan 41

Most of the available histochemical methods and techniques (azodye, metal salt and indigogenic methods, cryostat, free-floating and lyophilized section techniques) and different modifications of these methods (different substrate concentrations, pH, temperature, incubation time e.g.) were applied to study the distribution of acid phosphatase (AcPB = after Barka and Anderson; AcPG = after Gomori), beta-glucuronidase (beta-Glu), aryl sulfatase (AS), beta-N-acetylglucosaminidase (NAG), acid 5'-nucleotidase (a5-Nucl), non-specific esterase (NE) and alkaline phosphatase (AlP) in the kidneys of rats of both sexes. The optimal conditions for the demonstration of these enzymes were established. As most important proved: the incubation of free-floating sections cut from "standard"-fixed (2 h in formol-calcium continued for another 18-22 h in the same fixative plus 0.88 M sucrose at 4 degrees C) kidney slices - only for AcPB and NE material fixed after Holt had to be used; the incubation for AlP and NE at 4 degrees C; final pH of the incubation medium for AcPB 5.5, AcPG 5.0 and NE 6.5; the use of Fast Garnet GBC Salt as coupler in the NE azo-dye reaction. Sex differences and for the female rats an increased activity during oestrus were established for all hydrolases studied. In particular the following results were obtained: AcPB, a5-Nucl and A1P are more intensive in male and AcPG in female S1 segments of the juxtamedullary nephrons in relation to the nephrons of the other parts of the cortex. In the medullary rays the NE and the a5-Nucl show a higher activity in the S2 segments of female rats demonstrate a more intensive activity for NAG and NE. This is true for AcPG and A1P in male rats. In the inner medulla a stronger beta-Glu activity in male rats and a stronger NAG activity in female rats is observed. The AcPB activity of the cortical distal tubules is higher in male rats.
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PMID:[Distribution of some hydrolases in the rat kidney (author's transl)]. 626 81

All of the common cytochalasins activate superoxide anion release and exocytosis of beta-N-acetylglucosaminidase and lysozyme from guinea-pig polymorphonuclear leukocytes (neutrophils) incubated in a buffered sucrose medium. Half-maximal activation of both processes is produced by approx. 0.2 microM cytochalasin A, C greater than 2 microM cytochalasin B greater than or equal to 4-5 microM cytochalasin D, E. While maximal rates of O2- release and extents of exocytosis require extracellular calcium (1-2 mM), replacing sucrose with monovalent cation chlorides is inhibitory to neutrophil activation by cytochalasins. Na+, K+ or choline inhibit either cytochalasin B- or E-stimulated O2- production with IC50 values of 5-10 mM and inhibition occurs whether Cl-, NO3- or SCN- is the anion added with Na+ or K+. Release of beta-N-acetylglucosaminidase in control or cytochalasin B-stimulated cells is inhibited by NaCl(IC50 approximately 10 mM), while cytochalasin E-stimulated exocytosis is reduced less and K+ or choline chloride are ineffective in inhibiting either cytochalasin B- or E-stimulated exocytosis. Release of beta-glucuronidase, myeloperoxidase or acid phosphatase from neutrophils incubated in buffered sucrose is not stimulated by cytochalasin B. Stimulation of either O2- or beta-N-acetylglucosaminidase release by low concentrations of cytochalasin A is followed by inhibition of each at higher concentrations. It appears that all cytochalasins can activate both NAD(P)H oxidase and selective degranulation of neutrophils incubated in salt-restricted media and that differential inhibition of these two processes by monovalent cations and/or anions is produced at some step(s) subsequent to cytochalasin interaction with the cell.
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PMID:Activation of superoxide production and differential exocytosis in polymorphonuclear leukocytes by cytochalasins A, B, C, D and E. Effects of various ions. 627 16

This in vitro study examined the ability of various dietary fiber components to bind 7,12-dimethylbenz[a]anthracene (DMBA), a hydrocarbon carcinogen known to contaminate food. Bile salt solutions of DMBA were incubated with individual fiber materials under various conditions, and the degree of binding was assessed. Binding of DMBA from simple bile salt solution was greatest with delipidated bran greater than acid lignin greater than alpha-cellulose greater than unprocessed bran. Binding to acid lignin was slowly reversible, was constant within the pH range 4-8, and appeared independent of a bile salt-fiber interaction. Acid lignin bound DMBA from a mixed lipid-bile salt solution significantly, but less effectively than from pure bile salt solutions. DMBA biliary metabolites from Sprague-Dawley rats were bound less extensively to all the fiber materials than was the parent hydrocarbon, but following hydrolysis of the metabolites by beta-glucuronidase binding was significantly increased. These results indicate that there is considerable potential for dietary fiber to interact with DMBA and its metabolites in the lumen of the gastrointestinal tract, possibly influencing hydrocarbon carcinogen bioavailability.
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PMID:In vitro interaction of 7,12-dimethylbenz[a]anthracene and its biliary metabolites with dietary fiber. 630 23


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