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)

A method was developed for determination of D-glucaric acid by treatment with a bacterial extract containing glucarate dehydratase and ketodeoxyglucarate aldolase. This led to the quantitative formation of pyruvate, which was then assayed by use of lactate dehydrogenase. Measurements of D-glucarate in individual samples of human urine by this technique were compared with those by the commonly used method of beta-glucuronidase inhibition, and gave values for D-glucarate content which were about 25% higher, but with otherwise good correlation.
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PMID:An enzymatic determination of D-glucaric acid by conversion to pyruvate. 389 13

Urine from workers of a cold-rolling steel plant exposed to mineral oils were tested for the mutagenic activity by the Salmonella/microsome assay, and for D-glucaric acid content as a measure of hepatic mixed-function oxidase activity. An occupationally unexposed group served as control. The biological monitoring phase followed an environmental phase carried out in the working environment that showed a substantially low mutagenic/carcinogenic risk for the exposed workers. Urine samples were collected before, during and after work. From the results it was observed that the urinary mutagenicity was detectable only with TA98 strain in the presence of enzymatic activation (+ S9 mix). Further addition of beta-glucuronidase did not give any enhanced mutagenic effects. There was a significant difference in urinary mutagenicity between the exposed and control workers. However, in both groups the highest mutagenicity data was found in smokers: both exposed smoking workers and smoking controls had significantly higher urine mutagenicity than the non-smoking exposed and control workers. The results suggested a synergistic effect of smoking with exposure to mineral oils: the mutagenicity of urine from exposed smokers was significantly higher than that of control smokers. There was no difference in urinary D-glucaric acid results between exposed and unexposed groups, however, smokers of both groups had a significant increase in D-glucaric acid excretion. The authors suggest that even for this workplace with its low mutagenic/carcinogenic risk, smoking could interact with the complex mixtures present in the environment, and thus modify urinary mutagenicity data.
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PMID:Mutagenicity studies and D-glucaric acid determination in urine of workers exposed to mineral oils. 390 25

The most commonly used method for quantifying D-glucaric acid, the enzyme inhibition method, is a two-step procedure. In the first step of the present study, urine was boiled at acidic pH to convert glucaric acid to 1,4-glucarolactone, which inhibits beta-glucuronidase activity. In the second step, inhibition of beta-glucuronidase by the prepared urine was measured. This is an indirect measure of the D-glucaric acid concentration. The second step was adapted to a Cobas-Bio centrifugal analyzer. Values on a reference population obtained by the manual method were highly correlated with values obtained by the semiautomated method described here (r = 0.976, p = 0.25), and precision was comparable by the two methods. The throughput increased from 8 to 20 samples per day when the automated method was used.
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PMID:A semiautomated procedure for urinary D-glucaric acid using a centrifugal analyzer. 395 Dec 2

Studies on the activity of the glucuronic acid pathway in alloxan diabetic rabbits were carried out. Amount of D-glucaric acid, L-ascorbic acid, and D-glucuronic acid in urine increased in the case of the alloxan diabetic rabbits. The transformation from D-glucuronolactone to D-glucaric acid was higher than normal in the diabetic animals. The expired 14-CO2 decreased and urinary excretion of labeled L-gulonic acid increased after administration of 6-14-C-glucuronolactone in the diabetic rabbits. L-Gulonic acid dehydrogenase, lactonase II, and beta-glucuronidase activities were reduced, and UDPGA-pyrophosphatase, D-glucuronic acid-1-phosphatase, and UDPGA-transferase activities increased in the diabetic rabbit liver. From these results, it may be concluded that an increase of endogenous D-glucuronic acid in the diabetic states could be attributed to a metabolid defect in the step of L-gulonic acid dehydrogenation and to the enhancement of UDPGA-pyrophosphatase and D-glucuronic acid-1-phosphate phosphatase activities.
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PMID:Glucuronic acid pathway in alloxan diabetic rabbits. (I). Urinary excretion of metabolites related to the glucuronic acid pathway. 446 73

As measured by urinary D-glucaric acid excretion, an index of hepatic enzyme induction, glutethimide was the most powerful of six such inducers tested. In patients with tuberculosis, rifampicin, 450 mg daily, induced excretion rates of the lower dose range of anticonvulsants in epileptics. The effect was detectable in the first few days but the degree and rate of rise to maximum excretion were variable. This may be due either to disposition of rifampicin or to genetic susceptibility to enzyme induction. Plasma beta-glucuronidase, an essential enzyme of the glucuronic acid pathway, could be induced independently of an increase in D-glucaric acid excretion. Plasma gamma-glutamyltranspeptidase-levels, an index of hepatic microsomal enzyme induction, were elevated in only 20 of 83 subjects receiving rifampicin and isoniazid, and in all of them urinary D-glucaric acid excretion was normal. Neither of these indices, therefore, showed hepatic enzyme induction during combined therapy when other pathways such as oxidative metabolism continued to be induced. Different active sites of rifampicin and isoniazid on glucuronic acid and other biochemical pathways emphasize the complexity of final metabolic effects in patients on long-term therapy.
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PMID:Urinary D-glucaric acid excretion during rifampicin/isoniazid and anticonvulsant enzyme induction. 614 35

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

A rapid and sensitive procedure is described for the assay of rat liver microsomal UDP-glucuronosyltransferase activity toward the bile acids chenodeoxycholic acid, deoxycholic acid, ursodeoxycholic acid, and lithocholic acid using the radioactively labeled bile acids as substrates. The unreacted bile acids were separated from the bile acid glucuronides formed as products of the enzymatic reactions by extraction with chloroform, leaving the bile acid glucuronides in the aqueous phases. The bile acid glucuronides were characterized by their mobilities in thin-layer chromatography and identified by their sensitivity to hydrolysis with beta-glucuronidase and inhibition of hydrolysis by the specific beta-glucuronidase inhibitor D-saccharic acid-1,4-lactone. Enzyme activities were optimal at pH 6.8 and were maximally stimulated about fourfold by the addition of the nonionic detergent Brij 58 at a concentration of 0.3 mg/mg microsomal protein. The kinetic parameters for the various bile acids as substrates were determined.
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PMID:A rapid and sensitive method for the assay of UDP-glucuronosyltransferase activity toward bile acids. 641 8

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

Heparan sulfate (HS), a prominent component of vascular endothelial basal lamina, is cleaved into large Mr fragments and solubilized from subendothelial basal lamina-like matrix by metastatic murine B16 melanoma cells. We have examined the degradation products of HS and other purified glycosaminoglycans produced by B16 cells. Glycosaminoglycans 3H-labeled at their reducing termini or metabolically labeled with [35S]sulfate were incubated with B16 cell extracts in the absence or presence of D-saccharic acid 1,4-lactone, a potent exo-beta-glucuronidase inhibitor, and glycosaminoglycan fragments were analyzed by high speed gel permeation chromatography. HS isolated from bovine lung, Engelbreth-Holm-Swarm sarcoma, and subendothelial matrix were degraded into fragments of characteristic Mr, in contrast to hyaluronic acid, chondroitin 6-sulfate, chondroitin 4-sulfate, dermatan sulfate, keratan sulfate, and heparin which were essentially undegraded. Heparin, but not other glycosaminoglycans, inhibited HS degradation. The time dependence of HS degradation into particular Mr fragments indicated that HS was cleaved at specific intrachain sites. In order to determine specific HS cleavage points, HS prereduced with NaBH4 was incubated with a B16 cell extract and HS fragments were separated. The newly formed reducing termini of HS fragments were then reduced with NaB[3H]4, and the fragments hydrolyzed to monosaccharides by trifluoroacetic acid treatment and nitrous acid deamination. Since 3H-reduced terminal monosaccharides from HS fragments were overwhelmingly (greater than 90%) L-gulonic acid, the HS-degrading enzyme responsible is an endoglucuronidase (heparanase).
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PMID:Metastatic melanoma cell heparanase. Characterization of heparan sulfate degradation fragments produced by B16 melanoma endoglucuronidase. 669 65

The enzymatic methods for measuring D-glucaric acid in urine are based on the conversion of D-glucaric acid into its 1,4-lactone and measurement of inhibition of 1,4-lactone against beta-glucuronidase at pH 5.0. All the enzymatic methods described suffer from the disadvantage of a procedure that is complicated and inherently inaccurate, because the nature of glucaric acid/1,4-lactone equilibrium has not been properly considered in the development of such methods. After elucidating the factors influencing glucaric acid/1,4 lactone equilibrium in more detail, a low-pH enzymatic method has been developed in which the 1,4-lactone is formed in the urine sample by acid boiling at pH 3.8 and assayed at the same pH using beta-glucuronidase from Limpets. This procedure allows the acid/lactone equilibrium to remain stable during both the lactonization step and the enzymatic assay. The coefficient of variation for the proposed method (within-run and between-day precision) was from 4.2 to 8.7. The analytical recovery varied from 92-108%.
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PMID:Low-pH method for the enzymatic assay of D-glucaric acid in urine. 685 Nov 42


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