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)

Isopycnic equilibration and sedimentation rate studies of rat liver microsomes led previously to the assignment of microsomal constituents into group a1 (monoamine oxidase), group a2 (5'-nucleotidase, alkaline phosphodiesterase I, alkaline phosphatase and cholesterol), group a3 (galactosyltransferase), group b (NADH cytochrome c reductase, NADPH cytochrome c reductase, aminopyrine demethylase, cytochrome b(5) and P 450), and group c (glucose 6-phosphatase, esterase, nucleoside diphosphatase, beta-glucuronidase and glucuronyltransferase). Confirmation and extension of the assignment into groups has been obtained by studying the differential effect of the reagents digitonin, EDTA, and PPi. Digitonin specifically affected the equilibrium density only of the group a2 and (to a lesser extent) group a3, and not of groups b and c under conditions which preserved the structure-linked latency of nucleoside diphosphatase and galactosyltransferase. Within experimental error the rate of sedimentation of all microsomal constituents was unaffected. The morphological appearance under the electron microscope was indistinguishable from that of nondigitonin-treated microsomes, except that a few smooth membranes (< 10%) exhibited broken-looking profiles. Treatment of microsomes with EDTA or PPi detached a substantial part of RNA and released protein in excess over the amount accountable for by detachment of ribosome constituents. This detachment was confirmed by electron microscopy. EDTA and PPi decreased markedly the equilibrium density and the density dispersion of groups b and c, due mainly to the uncoating of rough elements. EDTA and PPi shifted slightly the distribution profiles of groups a towards lower densities, possibly as a result of the release of adsorbed proteins. The combination of EDTA and digitonin, used subsequently, rendered the average equilibrium density of group a2 higher than that of groups b and c. Dense subfractions were thus enriched in constituents of group a2 and showed mainly broken-looking vesicles under the electron microscope. The import of our results on the biochemical and enzymic properties of the subcellular components of the microsome fractions is discussed.
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PMID:Analytical study of microsomes and isolated subcellular membranes from rat liver. IV. Biochemical, physical, and morphological modifications of microsomal components induced by digitonin, EDTA, and pyrophosphate. 436 10

An ethyl anthranilate azopigment of bilirubin conjugated to beta-d-monoglucoside was isolated from dog gall-bladder bile. Glucose was cleaved from the azopigment by treatment with beta-glucosidase and beta-glucuronidase. Mild alkaline hydrolysis of the compound by sodium methoxide yielded two kinds of compounds, water-soluble and organic-soluble. The former were shown, by enzymic analysis, t.l.c., nuclear magnetic resonance, and combined g.l.c. and mass spectrometry, to contain glucose. No evidence was obtained from these data that a disaccharide was present in this fraction. The organic-soluble compounds formed during this methanolysis were shown, by t.l.c. and mass spectrometry, to be the isomeric dipyrrole azopigments of bilirubin. These findings contribute further evidence to the controversy surrounding the nature of conjugated bilirubin.
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PMID:The isolation of an azobilirubin beta-D-monoglucoside from dog gall-bladder bile. 446 61

1. The thio-beta-d-glucosiduronic acids (thio-beta-glucuronides) of o-aminothiophenol, diethyldithiocarbamic acid, p-nitrothiophenol and thiophenol are formed biosynthetically in broken- and intact-cell preparations of mouse liver. 2. For this biosynthesis to occur in homogenates or microsomal fractions, UDP-glucuronic acid was required during incubation; glucose, glucuronic acid or UDP could not replace it. UDP was a product of the reaction. 3. The biosynthetic mechanism linking glucuronic acid to thiol and carbodithioic groups therefore requires UDP-glucuronyltransferase activity and resembles that forming the various types of O-glucuronides. 4. An analogous enzymic mechanism employing UDP-glucose synthesizes the thio-beta-d-glucosides of diethyldithiocarbamic acid and thiophenol in gut preparations of the mollusc Arion ater; this mechanism resembles that forming the O-glucosides. The thio-beta-d-glucosides are formed also in intact cells. 5. As expected from the distribution of O-glycosides, S-glucuronides of these aglycones were not detectable with the invertebrate, nor were the S-glucosides with the vertebrate. 6. Despite their similar biosyntheses, S- and O-beta-glycosides differ in susceptibility to hydrolysis by beta-glycosidases. Rat preputial-gland beta-glucuronidase hydrolysed thioglucuronides of o-aminothiophenol, diethyldithiocarbamic acid and p-nitrothiophenol, hydrolysis being inhibited by glucarolactone; the thioglucuronide of thiophenol was not hydrolysed by preputial-gland or liver beta-glucuronidase. The two S-glucosides resisted hydrolysis by beta-glucosidase from almond emulsin.
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PMID:Mechanism of biosynthesis of thio- -D-glucuronides and thio- -D-glucosides. 465 87

1. Rat liver microsomal preparation can effect the transglucosylation from UDP-glucose to bilirubin in the presence of Mg(2+). 2. Other nucleotides, namely CDP-glucose, ADP-glucose and GDP-glucose, were not active as glucosyl donors. 3. Only trace amounts of galactose, galacturonic acid and N-acetylglucosamine were conjugated to bilirubin when their respective UDP derivatives were used in the reaction mixture. 4. The azobilirubin glucosides produced by coupling with p-diazobenzenesulphonic acid and diazotized ethyl anthranilic acid were separable from the corresponding azobilirubin glucuronides by t.l.c. 5. The glucoside was, however, hydrolysed by both beta-glucosidase and various preparations of beta-glucuronidase; azobilirubin and glucose were liberated in the process. 6. Kinetic studies showed that the effects of pH and Mg(2+) on the two conjugating systems were similar. 7. The specific activities of hepatic bilirubin UDP-glucosyltransferase, expressed as mug of bilirubin ;equivalents' conjugated/h per mg of protein, are respectively 1.7 and 2.4 for male and female rats. 8. The K(m) values for bilirubin and UDP-glucose are 5.7x10(-5)m and 1.6x10(-3)m respectively. 9. The glucoside and glucuronide conjugations of bilirubin are discussed in relation to the availability of the conjugating agents and aglycone in the liver.
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PMID:Formation of bilirubin glucoside. 514 54

A water-soluble metabolite, isolated from the urine of dogs given (S)-5-ethyl-5-phenylhydantoin [(S)-EPH], has been identified as 1-deoxy-1-[(5S)-5-ethyl-5-phenylhydantoin-3-yl] beta-D-glucopyranuronate [(S)-EPH N-glucuronide]. EPH N-glucuronide did not release the aglycone upon acid or beta-glucuronidase treatment, but incubation in alkaline solution (pH 12-13) readily formed 2-ethyl-2-phenylhydantoic acid (EPHA). The EPHA so formed could be quantitatively cyclized to EPH. With the knowledge of the conversion efficiency of EPH N-glucuronide to EPHA, a quantitative GLC assay for the metabolite was developed. EPH N-glucuronide was found to be the major urinary metabolite after administration to dogs of either (R)-, (S)-, or (RS)-EPH.
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PMID:5-ethyl-5-phenylhydantoin N-glucuronide, the major urinary metabolite of 5-ethyl-5-phenylhydantoin (Nirvanol) in the dog. 613 Sep 6

A major metabolite of the antiepileptic drug valproic acid (VPA) in animals and man is the glucuronic acid conjugate, which is cleaved by incubation with beta-glucuronidase (specific for 1-O-substituted-beta-D-glucopyranosiduronic acids) or hydrolysis in strong acid or alkali. Previous studies revealed that an often substantial proportion of the alkali-labile conjugated VPA in stored urine or bile samples was not hydrolyzed by beta-glucuronidase, suggesting the presence of nonglucuronide conjugates. In the present study, bile from a NaVPA-treated rat was preincubated at 37 degrees C for 3 hr at pH values from -0.8 to 12.9, and then analyzed for nonconjugated VPA, VPA released by hydrolysis with beta-glucuronidase, and VPA released by hydrolysis with alkali. At pH 3-7, all alkali-labile conjugated VPA remained susceptible to beta-glucuronidase hydrolysis, whereas at pH 0-3 and 7-11, a proportion became resistant to the enzyme. GLC and GC/MS analysis of trimethylsilyl derivatives of the intact conjugates revealed the appearance of seven additional peaks, adjacent to the biosynthetic ester glucuronide, of which six were structural isomers and one was a dehydrated species. The data were consistent with acid- and base-catalyzed intramolecular acyl migration of the valproate moiety away from the C-1 position, with subsequent processes of ring-opening, mutarotation, and lactonization yielding structural isomers and lactones which were not substrates for beta-glucuronidase. It was further shown that these rearrangements are time- and temperature-dependent. Consequently, sample handling and storage conditions of ester glucuronides prior to analysis are of prime importance, since hydrolysis with beta-glucuronidase is frequently used for identification and quantification of glucuronides.
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PMID:pH-dependent rearrangement of the biosynthetic ester glucuronide of valproic acid to beta-glucuronidase-resistant forms. 614 92

Recently, some knowledge of metabolic pathways, rather than individual enzyme activities of M. leprae, is becoming available. Ultimately this may be useful in devising culture media for M. leprae. Knowledge restricted to individual reactions may be misleading. For instance, the detection of GlcNacase and beta-glucuronidase and the subcellular localization of hyaluronic acid led to attempts to cultivate M. leprae on hyaluronic-acid based medium. Subsequent investigations suggested that there was no pathway for the breakdown of hyaluronic acid in M. leprae. The biochemical pathways for breaking down glucose and glycerol seem to be complete, and thus similar to many bacteria, but there is an unusually high level of one enzyme, 6-phosphogluconate dehydrogenase (6PGDH). Although 6-phosphogluconate is oxidized by M. leprae, and this is an unusual activity, reflecting very high levels of 6PGDH, glycerol may be a preferable energy source (on the basis of rates of oxidation by suspensions) for M. leprae in attempts to cultivate the bacterium. The utilization of 6-phosphogluconate might be important for other aspects of M. leprae metabolism not yet investigated (e.g., pentose metabolism) or it may be an adaption, not needed in vitro, to its existence in host macrophages. Alternatively, its oxidation may be a way of rapidly generating NADPH at critical times for the bacterium. Other unusual activities which have been reported are the presence of an enzyme characteristic of chemoautotrophism , completely surprising in view of the biology of M. leprae. This report needs to be confirmed--some aspects, in fact, have failed to be confirmed. o-Diphenoloxidase activity is unique, among mycobacteria, to M. leprae, but there is still doubt over whether or not it is an enzymatic activity and its function is unknown. A transpeptidase which may be involved in cell wall synthesis, recently demonstrated in M. leprae, is a typical mycobacterial enzyme. It is now known that iron could be supplied to M. leprae in potential media in the form of ferriexochelin from M. neoaurum . Two "deletions" in the metabolic processes of M. leprae have been observed. Catalase appears to be absent in M. leprae; its addition to media stimulates the growth of some organisms since peroxides form in the bacteriological media . Purine synthesis de novo occurred at a very low rate compared with purine scavenging. Whether this is an adaption to growth in vivo is not known.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Metabolism in Mycobacterium leprae: its relation to other research on M. leprae and to aspects of metabolism in other mycobacteria and intracellular parasites. 614 38

Fourteen male rabbits born at elevation 4000 ft (first experimental series) were transferred at age of 2 months to elevation 12470 ft and raised there for 18 weeks. Half of the animals remained on a commercial rabbit chow (group H) while the other half was on the same diet supplemented with cholesterol (group C). Eight male rabbits raised at sea level served as controls (group S). Intima-media homogenates from the thoracic aortas were assayed for lactate dehydrogenase (LDH), malate dehydrogenase (MDH), lipoamide dehydrogenase, pyruvate kinase (PK), phosphofructokinase (PFK) and the lysosomal hydrolases beta-glucuronidase and N-acetyl-beta-glucosaminidase (NAGA). Aortic lactate and glucose were also measured. Thirty-two male rabbits (second experimental series) were subdivided into 4 groups. Rabbits were fed a cholesterol-supplemented diet not only at high altitude (8 rabbits matching group C) but also 8 animals raised at sea level. The degree of atherosclerosis in the aortas of these 4 groups was assessed by measuring the aortic cholesterol contents. Plasma cholesterol was also determined. In the aortas of the rabbits of group H the activity of PK was significantly elevated, and the activity of the lysosomal hydrolases significantly decreased compared with aortas of group S rabbits. There was no difference in the other enzyme activities or in the aortic glucose and lactate content of these groups. Cholesterol feeding of the animals of group C resulted in a significantly increased activity of the lysosomal hydrolases as well as of LDH and PK. The lipid analyses (second experimental series) revealed a trend to a lower concentration of aortic cholesterol in the high altitude than in the sea level animals, both fed a cholesterol diet, in spite of the higher plasma cholesterol concentrations in the high altitude animals. The low aortic lysosomal hydrolase activities in the high altitude rabbits are in accord with their comparatively lower susceptibility to experimental atherosclerosis. This metabolic feature may be due to a lower degree of exposure of these aortas to injurious factors, such as infections or lower blood pressure. The elevated activity of PK without increased lactate content in group H animals seems to parallel the well-known general adaptation of the organism to high altitude hypoxia, and does not indicate a metabolic switch toward anaerobic glycolysis.
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PMID:Aortic enzymes and lactate in high altitude-raised and cholesterol-fed rabbits. 623 25

Abnormally low activity of hepatic bilirubin UDP-glucuronosyltransferase was found in 25% of 81 unselected patients with gallstones, as compared with only 3% in 35 controls. At the time of cholecystectomy, the stones were taken for analysis in 48 of 81 patients, and a bile sample was obtained in 42 of them. Among the stones, 75% were cholesterol stones, 15% pigment stones, and 10% 'intermediate' stones. Low hepatic conjugating activity was not preferentially associated with a given type of stone. No relation was found between the enzymic deficiency and the biliary cholesterol saturation index. A high proportion of biliary bilirubin monoglucuronide (over 40%) was found in four of seven patients with low transferase activity, as was earlier demonstrated in patients with overt Gilbert's syndrome. Raised biliary bilirubin monoglucuronide was also found in three patients, out of 46, who had normal transferase but raised biliary beta-glucuronidase activity. There was no evidence that deficient bilirubin conjugation could be a consequence of gallstones: the activity of another hepatic microsomal enzyme, glucose 6-phosphatase, taken as a reference, was measured in 12 patients and was always normal. Taking into account the very high frequency of a bilirubin centre in the cholesterol stones (87% of the cases in the present series), it is suggested that the increased proportion in poorly soluble biliary bilirubin monoglucuronide, which was associated with defective conjugation, could act as a trigger for gallstone initiation, regardless of the final composition of the stone.
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PMID:Possible role of a defect in hepatic bilirubin glucuronidation in the initiation of cholesterol gallstones. 625 64

The effect of dibutyryl cyclic AMP (dbc AMP) and PGE2 on the content and release of lysosomal and non-lysosomal enzymes was studied in a bone organ culture system using half calvaria from 6-7 day-old mice. In parallel the effect of dbc AMP and PGE2 on the release of calcium (Ca2+) and inorganic phosphate (Pi), glucose consumption and lactate production was also followed. DbcAMP (2.5 X 10(-4) M) decreased the release of beta-glucuronidase, beta-N-acetyl-glucosaminidase, acid phosphatase, Ca2+ and Pi during the first day of culture. During the 3rd and 4th day of dbcAMP increased all these parameters. In contrast no changes in the release of lactate dehydrogenase (LDH) and alanine aminotransferase (ALAT) were seen. Glucose consumption and lactate production was not stimulated by dbcAMP until the 3rd and 4th day. On the other hand, PGE2 (10(-7) M) stimulated the release of beta-glucuronidase, beta-N-acetylglucosaminidase, Ca2+ and Pi as well as glucose consumption and lactate production already after 24 h and this stimulation was maintained throughout the culture period. No effect by PGE2 on the release of LDH and ALAT was registered. The activities of LDH in the bone explants after 96 h of culture were significantly augmented by both dbcAMP and PGE2. It is concluded that bone resorption stimulated by dbcAMP and PGE2, is associated lysosomal enzyme release and lactate production.
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PMID:The effect of dibutyryl cyclic AMP and PGE2 on lysosomal enzyme release and lactate production in relation to bone resorption in vitro. 625 83


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