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)

1. A radiochemical method for the studies on the microsomal UDPglucuronic acid metabolism has been developed. 2. The rat liver microsomes caused a rapid hydrolysis of UDPglucuronic acid to D-glucuronic acid 1-phosphate and further although much slower to free D-glucuronic acid. In Tris-HCl buffer (pH 7.4) they were produced in ratio 72 : 1. No other metabolites were found in measurable amounts. The pyrophosphatase splitting UDPglucuronic acid showed a pH optimum at 8.9, but the liberation of D-glucuronic acid from UDPglucuronic acid had two pH maxima (pH 3.5 and 8.5). EDTA appeared to be less powerful inhibitor of pyrophosphatase than previously suggested. About 25 per cent of the UDPglucuronic acid hydrolyzing activity was still remaining in the presence of 10 mM EDTA. D-Glucaro-1,4-lactone was found to have a slight inhibitory action on the pyrophosphatase activity. Citrate inhibited powerfully the hydrolysis of UDPglucuronic acid and the liberation of free D-glucuronic acid. Phosphate was also inhibitory. 3. In the presence of an exogenous UDPglucuronosyltransferase substrate, 4-nitrophenol, the formation of D-glucuronic acid 1-phosphate and free D-glucuronic acid were slightly reduced, and D-glucuronic acid 1-phosphate, 4-nitrophenylglucuronide and free D-glucuronic acid were produced in ratio 78 : 23 : 1. When 10 mM EDTA was added to diminish the hydrolytic consumption of the glucuronyl donor substrate, the corresponding ratio was still as unfavorable as 19 : 2.6 : 1. The measurable activity of UDPglucuronosyltransferase was lower in the presence of phosphate or citrate than in Tris-HCl buffer, although they protected the glucuronyl donor substrate against hydrolysis. 4. The results indicate that even in the presence of added glucuronyl acceptor substrate the hydrolysis of UDPglucuronic acid predominates the conjugation in rat liver microsomes. The rate of the hydrolysis of UDPglucuronic acid is quite considerable even in the presence of EDTA, and it is recommended to control the UDPglucuronic acid pyrophosphatase activity when UDPglucuronosyltransferase and glucuronidation reactions are studied. Free D-glucuronic acid appears to be produced from UDPglucuronic acid for further use via D-glucuronic acid 1-phosphate, the rate-limiting step being the hydrolysis of this intermediate. UDP-glucuronosyltransferase, glucuronides of either endogenous or exogenous aglycones and beta-glucuronidase have only a minor role in this respect in rat liver microsomes.
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PMID:Pyrophosphatase and glucuronosyltransferase in microsomal UDPglucuronic-acid metabolism in the rat liver. 0 Dec 76

Neutrophil level in blood (1 l) and those of certain enzymes in neutrophils were measured in 36 patients with stomach tumors and 40 healthy controls. The range of the enzymes included myeloperoxidase (MPO), beta-glucuronidase (GR), N-acetyl-beta-D-glucosaminidase (NAG), acid phosphatase (AcP), alkaline phosphatase (AlP), lactate dehydrogenase (LD) and dehydrogenase-glucoso-6-phosphoric acid (DG-6-P). Glycogen and lipids were also assayed. The MPO and AcP levels of neutrophils in cancer patients were found to be significantly higher than in healthy controls, whereas the levels of the other enzymes were not. The glycogen and lipid concentrations in neutrophils in cancer patients were significantly lower than in healthy controls.
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PMID:[Histochemical characteristics of neutrophils of the peripheral blood in patients with cancer of the stomach]. 283 37

The liquid chromatographic (LC) method described, suitable for use with both blood plasma and urine, is applicable for determination of zearalenone and alpha-zearalenol at levels as low as 0.5 ng/mL plasma and 5 ng/mL urine. The sample is incubated overnight with beta-glucuronidase to analyze for both conjugated and unconjugated forms of zearalenone. The next day, the sample is acidified with H3PO4, extracted with chloroform, and evaporated to dryness. The residue is dissolved in toluene and loaded onto a silica gel cartridge which is washed with toluene and eluted with toluene-acetone (88 + 12). The eluate is evaporated, and the residue is dissolved in chloroform, extracted with 0.18M NaOH, neutralized with H3PO4, and re-extracted with chloroform. The chloroform extract is evaporated, dissolved in mobile phase for LC, and injected onto a normal phase column under the following chromatographic conditions: mobile phase of water-saturated dichloromethane containing 2% 1-propanol, and fluorescence detector, excitation wave-length 236 nm, and 418 nm cut-off emission filter. Recoveries of zearalenone and its metabolites from blood plasma and urine are 80-89% in the range 2.0-10 ng standard/mL plasma, and 81-90% in the range 10-30 ng standard/mL urine. This method was used to analyze blood and urine samples from a pig fed zearalenone-contaminated feed (5 mg/kg), corresponding to 80 micrograms/kg body weight. Zearalenone was rapidly metabolized to alpha-zearalenol, which appeared in the blood only 30 min after feeding. Almost all zearalenone and alpha-zearalenol was found conjugated with glucuronic acid in both blood plasma and urine.
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PMID:Quantitative liquid chromatographic method using fluorescence detection for determining zearalenone and its metabolites in blood plasma and urine. 316 69

beta-Glucuronidase from human maxillary sinus and lung cancers and from uninvolved tissues was studied. An elevation of beta-glucuronidase activity was observed in cancerous tissues as compared with the corresponding uninvolved tissues, and this increase was significant in adenocarcinoma and squamous cell carcinoma of the lung (p less than 0.01). beta-glucuronidase preparations purified from adenocarcinoma and large cell carcinoma of lung and from normal lung showed similar kinetic properties and antigenicity. beta-Glucuronidase from lung adenocarcinoma showed considerable negative charge heterogeneity in the pI range from 4.2 to 6.2 in an experiment involving isoelectric focusing on polyacrylamide gel. Similar charge heterogeneity was observed in the enzyme from lung large cell carcinoma. Upon treatment of the adenocarcinoma enzyme with exogenous alkaline phosphatase or endoglycosidase H, the heterogeneous variant forms of the tumor enzyme appeared to partly or completely lose their negative charge and to be converted into forms similar to those of the normal lung enzyme. An experiment on the labeling of beta-glucuronidase with [32P]-phosphoric acid provided further evidence that the acidic variants found in lung cancers are extensively phosphorylated forms of the enzyme.
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PMID:[beta-Glucuronidase in human maxillary sinus and lung cancers: elevation of activity level and appearance of phosphorylated variant forms]. 609 43

A method for the assay of glucuronidation of C- and N-hydroxylated metabolites of the carcinogen N-2-fluorenylacetamide is described. The method employs UDP-[U-14C ))glucuronic acid and Baker C18 extraction columns for separation of the glucuronides from their aglycones and from the glucuronic acid. The 14C-labeled glucuronides, generated by rat liver microsomes, are eluted from the columns with 30% (v/v) methanol after prewashing the columns and elution of the radioactivity of 14C-glucuronic acid with 1 mM ammonium acetate, pH 6.9. The radioactivity of the eluates is measured by scintillation counting. The method is modified for assays of glucuronidation of alpha-naphthol and p-nitrophenol in that 1 mM phosphoric acid is used instead of 1 mM ammonium acetate, and the method is potentially adaptable to other aglycones. By monitoring radioactivity or uv absorbance of the column eluates, it is shown that all aglycones, except p-nitrophenol, are retained on the columns during elution of their glucuronides with 30% (v/v) methanol and are eluted only when absolute methanol is used. The identity of the glucuronides is shown by their response to hydrolysis by beta-glucuronidase in the presence and absence of D-saccharic acid-1,4-lactone and, in some instances, by chromatographic and spectral analyses of the released aglycones.
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PMID:A novel assay of glucuronidation of C- and N-hydroxylated metabolites of the carcinogen N-2-fluorenylacetamide. 640 46

beta-Glucuronidase from human lung neoplasms of various histological types and from uninvolved tissues was studied. A significant elevation of beta-glucuronidase activity was observed in adenocarcinoma and squamous cell carcinoma of the lung as compared with the corresponding uninvolved tissues (P less than 0.01). Saccharo-1,4-lactone, a strong inhibitor of the enzyme, exhibited a substantially greater stabilizing effect on the adenocarcinoma enzyme than on the other enzymes. However, removal of the carbohydrate moiety from the adenocarcinoma enzyme by treatment with endo-beta-N-acetylglucosamidase H (endoglycosidase H) brought about a decrease in the stabilizing effect. Tumor beta-glucuronidase showed considerable negative charge heterogeneity in the pI range from 4.2 to 6.2 in isoelectric focusing on polyacrylamide gel. Upon treatment with exogenous alkaline phosphatase or endoglycosidase H, the heterogenous variant forms of the tumor enzyme appeared to partly or completely lose their negative charge and to be converted into forms similar to those of the normal lung enzyme. These data strongly suggest that the variants are highly phosphorylated on the oligosaccharide chains of the enzyme. An experiment on the labelling of beta-glucuronidase with [32P]-phosphoric acid provided further evidence that the acidic variants found in lung cancers are extensively phosphorylated forms of the enzyme.
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PMID:Cancer-associated alteration of beta-glucuronidase in human lung cancer: elevated activity and increased phosphorylation. 643 19

An automated HPLC method is described for the simultaneous determination of propranolol, 4-hydroxypropranolol, and N-desisopropylpropranolol in plasma and urine before and after beta-glucuronidase/aryl sulfatase treatment. It involves extraction with ether at pH 10 in the presence of ascorbic acid, added to prevent oxidation of 4-hydroxypropranolol. The compounds are then back extracted into dilute acid and assayed on an HPLC using a fluorescence detector. Three HPLC columns have been used (a phenyl, an octyl, and an octadecyl column). The last column was found to be most reproducible with minimal intercolumn variation. The solvent system includes a combination of acetonitrile, methanol, and phosphoric acid. Concentrations as low as 0.2, 1.0, and 0.2 ng/ml of propranolol, 4-hydroxypropranolol, and N-desisopropylpropranolol, respectively, can be measured using 1 ml of plasma.
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PMID:An automated HPLC method for the assay of propranolol and its basic metabolites in plasma and urine. 707 80

This assay method allows a simultaneous determination of imipramine, desipramine, their 2-hydroxylated metabolites, and imipramine-N-oxide in 0.5 ml of plasma or 0.1 ml of urine within 35 min by an ion-paired, reversed phase (C18) high-performance liquid chromatography (HPLC) with electrochemical detection. The analytes are extracted from alkalinized plasma or urine with 5 ml of a 90/10 mixture (by vol) of diethyl either/2-propanol, back-extracted into 0.5 ml of 0.1 mol/L phosphoric acid. Urine samples are enzymatically treated with beta-glucuronidase/arylsulfatase before extraction. The electrochemical detection is performed with a glassy carbon electrode set at +0.85 V against the Ag/AgCl reference electrode. Recoveries for the analytes and the internal standard (propericiazine) from plasma or urine ranged from 66.4 to 105.7% with coefficients of variation (CVs) of < 6.8%. The intra- and interassay CVs for the analytes were < 17.4% in plasma and < 14.2% in urine. The limits of determination (a signal-to-noise ratio of 3) for imipramine, desipramine, 2-hydroxyimipramine, 2-hydroxydesipramine, and imipramine-N-oxide were 0.5, 0.3, 0.02, 0.02, and 1.0 microgram/L, respectively. Only four of the 23 psychotropic drugs, which might be coadministered with imipramine or desipramine, were considered to be the possible sources to interfere with the assay. We evaluated clinical applicability of this method by determining plasma concentration- and urinary excretion-time courses of the respective analytes in an extensive and a poor metabolizer of the debrisoquine/sparteine-type oxidation after a single oral dose of imipramine HCl (25 mg). The present method appears to be suitable not only for the therapeutic drug monitoring of imipramine and its active metabolites but also for studying the pharmacogenetically related metabolism of imipramine or desipramine.
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PMID:Simultaneous high-performance liquid chromatography-electrochemical detection determination of imipramine, desipramine, their 2-hydroxylated metabolites, and imipramine N-oxide in human plasma and urine: preliminary application to oxidation pharmacogenetics. 833 3

We established a high-performance liquid chromatography (HPLC) method for the simultaneous determination of the camptothecin (CPT) derivative, irinotecan hydrochloride (CPT-11) and its metabolites, 7-ethyl-10-hydroxycamptothecin (SN-38) and SN-38 glucuronide (SN-38G) in rat plasma with a fully automated on-line solid-phase extraction system, PROSPEKT. Plasma samples were pretreated with 0.146 M H3PO4 to inactivate carboxylesterase and beta-glucuronidase in rat plasma, and added with the internal standard solution (0.146 M H3PO4 containing 1 microgram/ml CPT) and then analyzed. The method was validated for CPT-11 (5 to 25,000 ng/ml), SN-38 (5 to 2500 ng/ml) and SN-38G (2.5 to 500 ng/ml). This method enabled the determination of many samples within a relatively short time with easy sample preparation. It also had four advantages compared with conventional determination methods, i.e. automation of a complicated sample preparation, time-saving by the simultaneous determination of three compounds, the direct determination of SN-38G, and the small amount of plasma required for the determination.
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PMID:High-performance liquid chromatographic method for the simultaneous determination of the camptothecin derivative irinotecan hydrochloride, CPT-11, and its metabolites SN-38 and SN-38 glucuronide in rat plasma with a fully automated on-line solid-phase extraction system, PROSPEKT. 1021 76

The nature of quercetin conjugates present in blood after consumption of quercetin glucosides is still unclear. In this study, we analyzed plasma of volunteers that had consumed 325 micromol of either quercetin-3-glucoside or quercetin-4'-glucoside as an oral solution. Quercetin metabolites were extracted with acetonitrile/phosphoric acid and these extracts were analyzed using a high performance liquid chromatography with Coularray detection that distinguishes between the glucuronidated and the glucosylated forms of quercetin. No intact quercetin glucosides and only trace amounts of aglycone were found in human plasma, irrespective of the glucoside ingested. This was confirmed by spiking the plasma with glucoside standards. The major components in plasma had the same retention time as quercetin glucuronide standards. These plasma components disappeared after treatment of the plasma with bovine liver beta-glucuronidase, under reformation of quercetin, and showed the same oxidation pattern as the glucuronides. These results suggest that after consumption of quercetin glucosides, quercetin glucuronides are major metabolites in plasma.
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PMID:Quercetin glucuronides but not glucosides are present in human plasma after consumption of quercetin-3-glucoside or quercetin-4'-glucoside. 1143 10


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