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:3.2.1.21 (beta-glucosidase)
3,280 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Agar, carboxymethylcellulose, carrageenan, guar gum, gum acacia, locust-beam gum or pectin (50 g/kg diet), given to weanling rats for 4 wk, increased the weight of the caecal wall and the caecal contents. Feeding carboxymethylcellulose, guar gum or pectin significantly increased, and feeding carrageenan decreased, the total bacterial population of the caecum. Feeding carboxymethylcellulose significantly increased in vitro activity of bacterial azoreductase, beta-glucosidase, beta-glucuronidase, nitrate reductase, nitroreductase and urease. Guar gum, gum acacia and locust-bean gum each increased at least three of these activities. In contrast, feeding carrageenan greatly decreased all microbial enzyme activities, while agar decreased beta-glucosidase, beta-glucuronidase and nitroreductase activities.
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PMID:Hydrocolloid food additives and rat caecal microbial enzyme activities. 653 30

Weanling rats were fed low-fat (1% w/w safflower oil) or high-fat (1% w/w safflower oil plus 35% w/w beef fat or cocoa butter) diets for 30 days, and the activities of five cecal microbial enzymes were determined. When compared with the low-fat diet, beef fat significantly increased total cecal beta-glucuronidase activity, but cocoa butter, with a similar fatty acid composition, did not. Both high-fat diets significantly decreased total cecal azoreductase, beta-glucosidase, and nitrate reductase activities, but neither significantly affected urease activity. When expressed as specific activities (per 10(11) bacteria), cocoa butter decreased azoreductase, and beef fat caused increases of beta-glucuronidase and urease. Beef fat, but not cocoa butter, significantly reduced cecal bacterial numbers when compared to the low-fat diet. Both high-fat diets led to equivalent reductions in the proportion of aerobic bacteria.
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PMID:Dietary fat and cecal microbial activity in the rat. 654 72

Adult rats were fed diets containing 0, 25, 50, 100, 200, or 400 g lactalbumin/kg diet for 10 days, and the activities of six cecal microbial enzymes were determined. Total activity per cecum of azoreductase, beta-glucosidase, and urease increased significantly with increasing dietary protein, whereas the activities of beta-glucuronidase and nitroreductase were not significantly affected. Nitrate reductase activity decreased significantly. Total numbers of cecal bacteria were not significantly altered by the treatment.
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PMID:Dietary protein and cecal microbial metabolism in the rat. 687 47

Several hydrolytic and reductive bacterial enzymes (beta-glucuronidase, GN; beta-glucosidase, GS; arylsulphatase, AS; azoreductase, AR; nitroreductase, NR) involved in production of mutagenic or genotoxic metabolites were measured in human colonic contents. Cell-associated AS and extracellular GS were approximately twice as high in the distal colon compared with the proximal bowel, while AR changed little throughout the gut. Measurements of these enzymes in faeces from seven healthy donors confirmed that the majority were cell-associated, and demonstrated high levels of inter-individual variability. NR decreased four-fold between the proximal and distal colon while extracellular GN was reduced by 50%. Most probable number (MPN) analysis on faeces obtained from six healthy donors showed that counts of intestinal bacteria producing GS and AR were c. 10(10) and 10(11)/g, respectively, in all samples tested. Numbers of GN- and AS-forming organisms were between two and three orders of magnitude lower. Inter-individual carriage rates of bacterial populations synthesising NR were highly variable. Screening of 20 pure cultures of intestinal bacteria, belonging to six different genera, showed that Bacteroides ovatus, in particular, synthesised large amounts of GS, whereas B. fragilis, B. vulgatus and Bifidobacterium pseudolongum formed the highest cell-associated levels of GN. In general, bifidobacteria and Lactobacillus acidophilus did not produce significant amounts of AR. All five clostridia studied (Clostridium bifermentans, C. septicum, C. perfringens, C. sporogenes and C. butyricum) produced NR and AR, as did the bacteroides (B. fragilis, B. ovatus and B. vulgatus). Escherichia coli and C. perfringens formed large amounts of NR. Levels of AS production were invariably low and few of the organisms screened synthesised this enzyme. In-vitro studies investigating the effect of intestinal transit time on enzyme production, in a three-stage (V1-V3) continuous culture model of the colon operated at system retention times (R) of either 31.1 or 68.4 h, showed that specific activities of GS were up to four-fold higher (V3) at R = 31.1 h. Bacteriological analysis demonstrated that representative populations of colonic micro-organisms were maintained in the fermentation system, and indicated that changes in GS activity were not related to numbers of the predominant anaerobic or facultative anaerobic species within the model, but were explainable on the basis of substrate-induced modulation of bacterial metabolism.
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PMID:Ecological and physiological studies on large intestinal bacteria in relation to production of hydrolytic and reductive enzymes involved in formation of genotoxic metabolites. 987 41

Human consumption of chlorinated drinking water has been linked epidemiologically to bladder, kidney, and rectal cancers. The disinfection by-product (DBP) dichloroacetic acid is a hepatocarcinogen in Fischer 344 rats and B6C3F1 mice. The objective of this study is to determine the effect of the DBPs dichloro-, bromochloro-, and dibromoacetic acids (DCA, BCA, DBA) on intestinal microbial populations and their metabolism, with emphasis on enzymes involved in the bioactivation of procarcinogens and promutagens. One-month-old male Fischer 344 rats were provided water ad libitum containing 1 g/l DCA, BCA, or DBA for up to 5 weeks. At 1, 3, and 5 weeks of treatment, beta-glucuronidase (GLR), beta-galactosidase (GAL), beta-glucosidase (GLU), nitroreductase (NR), azoreductase (AR), and dechlorinase (DC) activities were determined in cecal and small and large intestinal homogenates. After 5 weeks of treatment, intestinal populations were enumerated on selective media. Cecal GAL (DCA, BCA, DBA) and GLR (DCA, DBA) activities were reduced after 1 and 3 weeks of treatment and GAL activity was elevated at 5 weeks (BCA). Large intestinal GAL (DCA, BCA) and GLU (DCA, BCA, DBA) activities were elevated after 5 weeks of treatment. Week 5 cecal AR (DCA, BCA, DBA), NR (DCA), and DC (DCA, DBA) activities were reduced. Even though some significant changes in intestinal populations were observed, use of selective media was not sensitive enough to explain fluctuations in enzyme activity. Haloacetic acids in the drinking water alter intestinal metabolism, which could influence bioactivation of promutagens and procarcinogens in the drinking water.
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PMID:The disinfection by-products dichloro-, dibromo-, and bromochloroacetic acid impact intestinal microflora and metabolism in Fischer 344 rats upon exposure in drinking water. 1091 Sep 85

We developed a new two-chamber system for the coculture of hepatocytes and fecal microflora under aerobic and anaerobic conditions, respectively, to investigate the sequential metabolism of chemicals by the liver and microflora in vitro. The culture device consisted of two chambers separated by a permeable polycarbonate membrane. In the aerobic compartment, hepatocytes were cultivated as a monolayer on the membrane and in the anaerobic compartment fecal microflora as a suspension. To characterize the metabolic capacity of the microflora and hepatocytes, various marker enzymes were studied. Azoreductase, nitroductase, beta-glucuronidase, beta-glucosidase and sulphatase were tested in the microflora of the feces from three volunteers who had had significantly different eating habits for years (daily meat, mixed diet, vegetarian). The microflora exhibited significant activities and the various enzymes differed only moderately in the samples from the three volunteers. For rat hepatocytes the activities of various cytochrome P450 forms and conjugating enzymes served as markers. The enzyme activities were tested in the coculture system during a 4-h culture period intended for the test protocol. Deethylation of ethoxycoumarin and 2alpha-, 6beta- and 16alpha-hydroxylation of testosterone decreased by about 30%, 25%, 40% and 20%, respectively, while there was no loss of glucuronidation and sulphonation of 3-OH-benzo(a)pyrene nor of glutathione conjugation of 1-chloro-2,4-dinitrobenzene during the 4-h culture period. The activities of the tested hepatic phase I and II enzymes were not changed after coculture of the hepatocytes with the microflora for 4 h. The applicability of the in vitro system for studying the metabolic interaction of liver and microflora was demonstrated using 7-ethoxycoumarin and the developmental drug EMD 57033, a thiadiazinon derivative from Merck KGaA, as model compounds. Both compounds were oxidized and conjugated by liver cells. In the coculture of hepatocytes and fecal microflora the resulting glucuronides and sulphoconjugates were split by hydrolytic enzymes of the intestinal microflora.
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PMID:Establishment of a novel in vitro system for studying the interaction of xenobiotic metabolism of liver and intestinal microflora. 1104 93

Haloacetic acids are by-products of drinking water disinfection. Several compounds in this class are genotoxic and have been identified as rodent hepatocarcinogens. Enzymes produced by the normal intestinal bacteria can transform some promutagens and procarcinogens to their biologically active forms. The present study was designed to investigate the influence of the cecal microbiota on the mutagenicity of haloacetic acids, and to look at changes in the microbiota populations and enzyme activities associated with exposure to haloacetic acids. PYG medium containing 1 mg/ml of monochloroacetic (MCA), monobromoacetic (MBA), dichloroacetic (DCA), dibromoacetic (DBA), trichloroacetic (TCA), tribromoacetic (TBA), or bromochloroacetic (BCA) acid was inoculated with rat cecal homogenate and incubated anaerobically at 37 degrees C. Growth curves were performed with enumeration of the microflora populations on selective media. Mutagenicity in a Salmonella microsuspension bioassay was determined after incubation for various lengths of time, with or without the cecal microbiota. At 15 h of incubation, enzyme assays determined the activities for beta-glucuronidase, beta-galactosidase, beta-glucosidase, azoreductase, nitroreductase, dechlorinase, and dehydrochlorinase. The haloacetic acids, with the exception of BCA, were toxic to the cecal microbiota, and especially to the enterococci. DBA, TBA, and BCA were mutagenic in the microsuspension assay, but the presence of the intestinal flora did not significantly alter the mutagenicity. BCA increased the activities of several enzymes, and therefore has the potential to affect the biotransformation of co-exposed compounds.
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PMID:Metabolism, microflora effects, and genotoxicity in haloacetic acid-treated cultures of rat cecal microbiota. 1124 34

Supplementation of the human diet with prebiotic substances such as inulin and non-digestible oligosaccharides (NDO), e.g., galacto-oligosaccharides (GOS), has been associated with various health benefits. However, little information is available regarding the spatial location of their metabolism in human gut bacterial ecosystems. Therefore, the present study investigated the metabolism of inulin and GOS with respect to bacterial growth, bifidobacterial stimulatory properties and anti-mutagenicity potential, in a three-stage continuous culture model of the colon which reproduces the physicochemical characteristics of the proximal (V1) and distal (V2, V3) colons. Fermentation of both carbohydrates was rapid, and occurred primarily in V1, as evidenced by acid formation. Inulin metabolism was associated with 10-fold stimulation of lactobacillus populations, together with smaller increases in bifidobacterial cell counts in V1. However, peptostreptococci, enterococci and Clostridium perfringens also increased in this fermentation vessel. In contrast, GOS was only weakly bifidogenic in V1, although these bacteria did proliferate in V2. GOS also increased lactobacilli by an order of magnitude in V1. However, overall changes in microbial populations resulting from inulin or GOS addition were minimal in V2 and V3. Potential beneficial effects of inulin metabolism included minor reductions in beta-glucosidase and beta-glucuronidase, whereas GOS strongly suppressed these enzymes, together with arylsulphatase (AS). Growth of putatively health promoting micro-organisms was not only associated with reductions in enzymes linked to genotoxicity. For example, both carbohydrates stimulated synthesis of nitroreductase and azoreductase, throughout the fermentation system, while inulin increased AS. Colonic transit time is an important factor in bacterial metabolism in the large bowel, and these data suggest that, in some circumstances, NDO fermentation will occurprincipally in the proximal colon.
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PMID:Modulation of genotoxic enzyme activities by non-digestible oligosaccharide metabolism in in-vitro human gut bacterial ecosystems. 1154 86

The activities of four microbial enzymes (azoreductase, nitroreductase, beta-glucuronidase, and beta-glucosidase) in major anaerobic members of human fecal microflora were quantified and the influence of the host factors on expression of these microbial enzyme activities was also investigated. Clostridium paraputrificum and C. clostridiiforme showed much higher activities than other fecal anaerobes tested. Nitroreductase activity in C. paraputrificum isolated from fecal specimens of patients with colon cancer was significantly (P < 0.05) higher than that in the clostridia isolated from healthy subjects and the subjects given high beef diets. However, the activities of some microorganisms tested showed marked differences in each strain.
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PMID:Comparison of four microbial enzymes in Clostridia and Bacteroides isolated from human feces. 1222 35

The effect of fructooligosaccharides (FOS) on cecal enzyme activity was studied. Adult male Wistar rats were fed a fiber-free diet supplemented with 5% cellulose, a 5% mixture (1:1) of cellulose and FOS or 5% FOS as a source of fiber for 4 weeks. The cecal content was used to measure azoreductase, beta-glucuronidase, beta-glucosidase, nitrate reductase and nitroreductase activities. Cellulose-fed diet increased significantly body weight gain, food intake and fecal stool weight compared to FOS-fed diet. No differences in food intake between FOS-containing diets were found. FOS-containing diets showed statistically higher weight of cecal content and weight of cecal wall compared with the cellulose group. There were significant differences in cecal enzyme activities between cellulose-fed rats and FOS-fed rats. Cellulose-FOS-fed diet decreased significantly nitroreductase, beta-glucuronidase and beta-glucosidase enzymes, but did not differ statistically in azoreductase and nitrate reductase compared with the control group. FOS-fed diet increased significantly reductive enzymes and decreased hydrolytic enzymes compared with the cellulose group. The incorporation of cellulose in diet seems to affect the prebiotic effect of FOS, since both cellulose and FOS are possible substrates for bifidobacteria proliferation. The results suggest that a mixture of cellulose and FOS as a source of dietary fiber could have a healthier effect on bacterial enzyme activities than each type of dietary fiber alone.
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PMID:Effect of short-chain fructooligosaccharides and cellulose on cecal enzyme activities in rats. 1246 25


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