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

Toxicity tests on Culex pipiens fatigans with propoxur (o-isopropoxyphenyl methylcarbamate) and carbofuran (2,2-dimethyl-2,3-dihydrobenzofuranyl-7-methylcarbamate) indicated that both compounds are fast-acting insecticides. Transfer of treated larvae to fresh water results in their partial recovery from knockdown.Propoxur is metabolized by resistant and susceptible larvae by their homogenate-reduced nicotinamide-adenine dinucleotide phosphate (NADPH(2)) enzyme system and by the microsome-plus-soluble fraction of mouse-liver extracts to at least 10 organosoluble metabolites with the isopropoxy group intact. The major metabolites, which are primarily hydroxylation products or the result of degradation of these products, have tentatively been identified as: acetone plus o-hydroxyphenyl methylcarbamate, 2-isopropoxy-5-hydroxyphenyl methylcarbamate, 2-isopropoxyphenyl carbamate, and 2-isopropoxyphenyl N-hydroxymethylcarbamate. Upon incubation of water-soluble products from treated larvae with beta-glucosidase, beta-glucuronidase, aryl sulfatase and acid phosphatase, the conjugates are hydrolysed, liberating mainly hydroxylated carbamates.The results indicate that slower absorption as well as faster detoxification by hydroxylation mechanisms, together with conjugation with polar molecules and elimination, are major factors in resistance of mosquito larvae to substituted-aryl methylcarbamate insecticides.
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PMID:Carbamate resistance in mosquitos. The metabolism of propoxur by susceptible and resistant larvae of Culex pipiens fatigans. 531 55

Human colostral macrophages stimulated by opsonized zymosan or phorbol myristate acetate (PMA) released superoxide anions (O2-) and hydrogen peroxide (H2O2) with activities comparable to those of monocytes and about one-fourth of those of polymorphonuclear leukocytes (PMNL) of blood. The O2- -forming oxidase in the macrophages stimulated by PMA was dependent on NADPH as an electron donor with an apparent Km value for NADPH of 27.6 +/- 4.0 microM, which is comparable to those obtained for the stimulated monocytes and PMNL of blood. The Vmax was 1.86 +/- 0.33 nmol O2/min/10(6) cells, which is essentially the same as that of monocytes and about half of that of PMNL. p-Chloromercuribenzoate or cetyltrimethylammonium bromide completely inhibited oxidases of all three types of phagocytes. A b-type cytochrome was identified in the macrophages but the concentrations in the macrophages and monocytes were less than half of that in PMNL. These results suggest that the differences in the O2- -forming activities of the three types of phagocytes are quantitative rather than qualitative. The macrophages and monocytes showed very low activities of myeloperoxidase [EC 1.11.1.7] in contrast to PMNL. The activity of beta-glucuronidase [EC 3.2.1.31] in the macrophages was much higher than those of the monocytes and PMNL, but little difference was observed in the activities of lysozyme [EC 3.2.1.17], catalase [EC 1.11.1.6] and superoxide dismutase [EC 1.15.1.1] among the three types of phagocytes examined. Electron micrographs of the macrophages showed little increase of vacuoles upon exposure to PMA, in contrast to the cases of monocytes and PMNL.
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PMID:Oxygen metabolism of human colostral macrophages: comparison with monocytes and polymorphonuclear leukocytes. 608

In order to resolve discrepancies in the literature concerning the subcellular localization of NADPH oxidase, we disrupted human neutrophils by nitrogen cavitation and fractionated the subcellular organelles on a discontinuous sucrose density gradient. The lightest fraction was 20- to 40-fold enriched for plasma membranes as determined by the marker enzymes alkaline phosphatase and phosphodiesterase I as well as by the ratio of lipid phosphorus to protein. There was a significant decrease in the specific activities of the granule markers myeloperoxidase, lysozyme, and beta-glucuronidase. An intermediate fraction was enriched in membrane markers but not to the extent the lightest fraction was enriched. This fraction contained more granular contamination, as shown by the marker enzymes. In contrast, the densest bands of the gradient were enriched for granule markers with little contamination by plasma membrane. Superoxide generation and NADP formation were primarily associated with the two membrane-enriched fractions from polymorphonuclear leukocytes stimulated with phorbol myristate acetate. The NADP formation associated with a dense granule fraction observed previously in our laboratory was probably due to a cyanide-stimulated oxidation of NADPH by myeloperoxidase.
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PMID:Co-localization of superoxide generation and NADP formation in plasma membrane fractions from human neutrophils. 609 76

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

To study the relationship between lipid peroxidation (LPO) and the release of lysosomal enzymes as markers of liver injury three compounds were chosen which evoke lipid peroxidation (cumene hydroperoxide, CHP), hepatocellular injury (thioacetamide, TAA) or both (carbon tetrachloride, CCl4). Premitochondrial supernatants of phenobarbital-induced rat liver homogenates were incubated in the presence of either agent and an NADPH-regenerating system. Then, lipid peroxidation was assessed by measurement of malondialdehyde (MDA) formation and, after centrifugation at 105 000 g, released beta-glucuronidase was measured in the supernatant. While CCl4 and CHP promoted both events in a time and concentration dependent manner, TAA did not evoke either LPO or lysosomal enzyme release. Glutathione, dithiocarb and (+)-catechin inhibited both effects. Though LPO and lysosomal enzyme release proved to be related events, no strict correlation with the hepatotoxicity was found.
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PMID:Interrelation between lipid peroxidation and lysosomal enzyme release in the presence of carbon tetrachloride, cumene hydroperoxide or thioacetamide. 630 41

In porcine interareolar placental epithelia, the following enzymes were demonstrated by histochemical methods after 30, 58, 80, 100, and 110 d of pregnancy, respectively: beta-N-acetylhexosaminidase, beta-galactosidase, beta-glucuronidase, alpha-mannosidase, acid phosphatase, alkaline phosphatase, nonspecific esterases, cytochrome oxidase, 5-nucleotidase, leucine aminopeptidase, adenosine triphosphatase, diaphorases (NADH, NADPH), glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, succinate dehydrogenase, isocitrate dehydrogenase (NAD, NADP), beta-hydroxybutyrate dehydrogenase, glycero-3-phosphate dehydrogenase, NAD-glycero-3-phosphate dehydrogenase, glutamate dehydrogenase (NAD, NADP), lactate dehydrogenase. The results show that most of the enzyme activities remained almost unchanged during the period of investigation. Only G-6-PDH and 6-PGDH activities increased within the uterine epithelium and nonspecific esterase activity within uterine as well as chorionic epithelia during the 2nd half of pregnancy. Within chorionic and uterine epithelia, hydrolases but not dehydrogenases demonstrated a higher activity at the bases of chorionic villi as compared to the apices and flanks of the latter. The action and influence of the demonstrated enzymes on metabolism, energy transfer, secretory, and resorptive activities of chorionic and uterine epithelia are discussed.
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PMID:[Enzyme histochemical studies of the swine placenta. Histoptics of enzymes in interareolar placental epithelia]. 643 35

The metabolism of endogenous estrogens, estradiol and estrone, and the irreversible binding of estrogens to cellular macromolecules have been examined and compared in subcellular microsomal and in intact hepatocyte preparations. In studies with rat liver microsomal preparations containing estradiol, an NADPH-generating system, and denatured DNA, the irreversible binding of radiolabeled steroid metabolite(s) to the microsomal proteins was 3.26 nmoles/mg protein in 1 hr (S.D. 0.39; 7.9% of total steroid) while binding to DNA was found to be 0.288 nmole/mg DNA/mg protein (S.D. 0.025; 0.39% of total steroid). No significant difference was observed between microsomal preparations from untreated, phenobarbital-treated or 3-methylcholanthrene-treated rats. Irreversible binding to proteins was also demonstrated in the intact hepatocyte cell incubations. After 2-hr incubations of estradiol with hepatocytes, 5.9% (S.D. 1.4%) of the steroid(s) was irreversibly associated with cellular proteins (approximately 1.43 pmoles/mg/min). Analysis of the organic-soluble metabolites demonstrated the presence of the catechol estrogens and their metabolites, 2-hydroxyestradiol, 2-hydroxyestrone, 2-methoxyestradiol, and 2-methoxyestrone. Estrone and estriol were also identified. The aqueous-soluble materials isolated from hepatocyte incubations contained glucuronide, sulfate, and apparent thioether conjugates, as determined by liberation from estrogen metabolites by treatment with beta-glucuronidase, sulfatase, and Raney nickel. Thus, extensive primary and secondary metabolism of estrogens occurs in intact hepatocyte incubations. Furthermore, irreversible binding of estrogens to cellular proteins occurs in these intact cells having demonstrated conjugative pathways of metabolism.
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PMID:Estrogen metabolism in rat liver microsomal and isolated hepatocyte preparations--I. Metabolite formation and irreversible binding to cellular macromolecules. 650 37

In this communication, the results of applying various histochemical techniques for the localization of oxidoreductases, transferases, hydrolases and isomerases in the human heart are presented. The Purkinje fibres of the atrioventricular conducting system of the human heart differ from the myocardium proper in containing a slightly higher activity of most of the glycolytic and gluconeogenetic enzymes investigated. The relatively higher activity of 6-phosphofructokinase, the key enzyme in anaerobic carbohydrate metabolism, is especially noteworthy. On the other hand, the activities of some of the enzymes that play a part in the aerobic energy metabolism is slightly less than those in the myocardium fibres. As for the activity of the NADPH regenerating enzymes, the activity of 6-phosphogluconate dehydrogenase and malate dehydrogenase (oxaloacetate-decarboxylating) is somewhat higher, and the activity of glucose-6-phosphate dehydrogenase similar, in the Purkinje fibres compared to that in the myocardial fibres. The activity of myosin ATPase is similar for both types of fibre. Likewise, the fibres of the conducting system and of the myocardium show a similar activity of acid phosphatase, beta-glucuronidase, non-specific naphthylesterase and peroxidase. The neurogenic function of the conducting system of the human heart was demonstrated by the high activity of acetylcholinesterase in the Purkinje fibres and in the atrioventricular node. All these histochemical findings in Purkinje fibres are similar at widely differing levels of the conducting system.
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PMID:Enzyme histochemical studies on the conducting system of the human heart. 744 Feb 54

The glucuronidation of the food-borne heterocyclic amine 2-amino-1-methyl-6-phenylimidazo-[4,5-b]pyridine (PhIP) was investigated using hepatic microsomes from several species. PhIP-glucuronic acid conjugates were formed in an NADPH-free system using microsomes from rabbit, dog, guinea pig, and human. Rat, hamster, and mouse microsomes were incapable of directly producing PhIP-glucuronides. The PhIP-glucuronide generated with human microsomes could be resolved by reverse-phase HPLC from that produced with rabbit microsomes. In addition, the human PhIP-glucuronide was susceptible to enzymatic hydrolysis by beta-glucuronidase, whereas the rabbit PhIP-glucuronide did not undergo beta-glucuronidase catalyzed hydrolysis. Fast atom bombardment mass spectrometry of both glucuronides revealed the presence of ions with m/z 401 (M+H+). Rabbit PhIP-glucuronide had a lambda max of 316 nm, similar to that of the parent PhIP. By contrast, a spectral shift in UV absorbance was observed for the human PhIP-glucuronide, which had a lambda max of 305 nm. 1H-NMR spectroscopy and nuclear Overhauser enhancements established that rabbit PhIP-glucuronide was conjugated at the exocyclic amine nitrogen, whereas human PhIP-glucuronide was conjugated at the N3 imidazole ring nitrogen. Km values for PhIP were 0.2-0.3 mM in both species; however, rabbit microsomes exhibited a 22-fold higher Vmax. Collectively, these studies indicate that human and rabbit liver microsomes form structurally different glucuronides of PhIP and suggest the involvement of multiple isoforms of UDP-glucuronosyltransferase. Further, these data suggest that in certain species, including humans, the direct conjugation of PhIP with glucuronic acid may represent a primary route of PhIP metabolism and detoxication.
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PMID:The direct glucuronidation of 2-amino-1-methyl-6-phenylimidazo[4,5-b] pyridine (PhIP) by human and rabbit liver microsomes. 811 24


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