Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.7.1.2 (nitrate reductase)
 3,861 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To investigate the involvement of bacterial enzyme activities in the biotransformation of xenobiotic compounds, we have developed a simulation of the rat hindgut microflora in vitro. This mixed bacterial population exhibits many similarities to the native rat flora, and the diversity of bacterial species and the activity of a number of hydrolytic and reductive enzymes (e.g. azoreductase, beta-glucosidase, beta-glucuronidase, nitrate reductase and nitroreductase) are reproduced in the culture at levels similar to those found in the large intestine. The flora have been found to respond to an anutrient (cyclamate) or to host products (bile acids) with changes in enzyme activity, and to metabolize the azo dye Brown HT to metabolites qualitatively similar to those found in the faeces after oral administration to the rat. The experiments demonstrate that the bacterial population of the large intestine of the rat may be successfully cultured in vitro and provides and alternative to animal studies for the investigation of foreign compound metabolism by the flora.
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PMID:The use of continuous flow systems for studying the metabolic activity of the hindgut microflora in vitro. 243 Aug 72

The activities of three bacterial biotransformation enzymes (beta-glucuronidase, beta-glucosidase, nitrate reductase) were determined in suspensions of rat caecal contents or human faeces over the pH range 6-8. All three enzymes were influenced by pH, as exemplified by beta-glucosidase activity which diminished as pH increased. In other instances the rat and human flora showed distinct profiles, with nitrate reductase activity undetectable in human faeces below pH 6.6, whereas the rat caecal flora displayed optimal reduction of nitrate around neutrality. The most pronounced host-species difference was found with beta-glucuronidase, which showed maximal activity at pH 6.0 in human faecal bacteria, while the rat caecal flora expressed greatest activity at pH 8.0. All three enzyme activities were associated with that fraction of rat caecal or human faecal material sedimented by centrifugation at 5000 g for 15 min, with little or no metabolism occurring in the 11,000 g supernatant fluid. The results demonstrate that pH has a pronounced effect on the enzymic activity of bacterial preparations from rat and human sources.
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PMID:The influence of incubation pH on the activity of rat and human gut flora enzymes. 250 31

The activities of four bacterial biotransformation enzymes (beta-glucosidase, beta-glucuronidase, nitrate reductase and nitroreductase) were measured in the caecal contents of conventional flora rats or germ-free rats contaminated with a mixed, human faecal flora and compared with activities present in a fresh human stool preparation. Both the conventional flora rats and the rats inoculated with a human flora exhibited an enzyme profile generally similar to that of human faeces, although the conventional rat flora exhibited negligible nitrate reductase activity. The enzyme profile remained essentially unaltered in both human flora preparations following supplementation of the diet with pectin, whereas the conventional rat flora responded to this plant cell wall carbohydrate with a significant increase in nitrate reductase activity. The results demonstrate that enzymic activities of the human faecal microflora can be simulated in rats associated with a mixed population of human intestinal bacteria.
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PMID:The use of rats associated with a human faecal flora as a model for studying the effects of diet on the human gut microflora. 282 Sep 14

The enzyme activity of the caecal microflora from weanling rats was determined after feeding 1 of 3 basal diets (purified fibre-free; purified plus cellulose; and stock), with or without additional dietary fibre (pectin, i-carrageenan or carboxymethylcellulose 5% w/w). The wet weight of caecal contents and total bacterial numbers were similar for the purified fibre-free and purified plus cellulose diets, yet were significantly higher in animals fed the stock diet. Pectin supplementation of the basal diets had no effect of caecal bacterial numbers, but significantly increased total nitrate reductase activity per caecum except when added to stock diet. Carrageenan decreased caecal bacterial numbers and most enzyme activities with both purified diets, and to a lesser extent with the stock diet. Carboxymethylcellulose increased bacterial numbers and enzyme activities, particularly beta-glucosidase and nitrate reductase when added to the purified diet but not when added to either the purified diet plus cellulose or the stock diet. The results demonstrate that the effects of dietary fibre components on the rat caecal microflora are dependent upon the initial fibre content of the diet base.
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PMID:Effect of mixtures of dietary fibres on the enzyme activity of the rat caecal microflora. 300 68

For 30 days, male weanling rats were fed a semipurified, fiber-free diet or a diet that contained 5, 15, or 30% (wt/wt) wheat bran. The activities of four cecal microbial enzymes were determined. Wheat bran significantly increased the wet weight content of the cecum and total bacterial count per cecum at the intermediate- and high-treatment levels, but it had no effect on bacterial concentration per gram wet weight of cecal contents. Total beta-glucosidase and beta-glucuronidase activities per cecum were generally increased. Wheat bran decreased total nitrate reductase activity, but there was no change in total nitroreductase activity. Wheat bran significantly decreased enzyme activities for nitro-and nitrate reduction per gram of cecal contents but increased beta-glucosidase activity. The activities of the enzymes per 10(11) bacteria followed a similar pattern to that noted per gram of cecal contents. Such fiber-dependent changes in enzyme activity may alter the steady-state concentration of toxic and genotoxic chemicals in the lumen of the hindgut.
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PMID:Influence of wheat bran on some reductive and hydrolytic activities of the rat cecal flora. 301 Feb 50

A comparison was made in six species of animal (rat, mouse, hamster, guinea-pig, marmoset and man) of five enzyme activities associated with the hindgut microflora. Marked differences were found in the caecal activities of azoreductase, beta-glucosidase, beta-glucuronidase, nitrate reductase and nitroreductase in the four rodents, with no one species exhibiting consistently higher or lower enzyme activity. None of the laboratory animals, including the marmoset, provided an approximation of the enzyme profile associated with human faecal flora. The results indicate that it may be invalid to extrapolate the results of bacterial metabolic studies between closely related species, or from animals to man.
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PMID:Enzyme activities of the hindgut microflora of laboratory animals and man. 375 Nov 8

Male Sprague-Dawley rats were fed a purified fibre-free diet containing 5% (w/w) sodium saccharin for 4 weeks or 20 weeks and changes in caecal bacterial numbers and enzyme activities (endogenous ammonia production, beta-glucosidase, beta-glucuronidase, nitrate reductase, nitroreductase, aryl sulphatase) determined in vitro. Saccharin treatment gave marked caecal enlargement but had no effect on bacterial concentration at either treatment period, and significantly decreased beta-glucuronidase, nitrate reductase and sulphatase activities/g caecal contents. The incubation of a suspension of caecal contents from control rats with saccharin (75 mM) in vitro inhibited beta-glucuronidase and nitrate reductase activities, and ammonia production from endogenous substrates. Such changes may decrease the rate of formation of toxic bacterial products in the hindgut.
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PMID:Modification of rat caecal microbial biotransformation activities by dietary saccharin. 384 Feb 94

The activities of four enzymes (beta-glucuronidase, nitrate reductase and nitroreductase) in selected intestinal bacteria (Escherichia coli, Clostridium sp., Streptococcus sp., Bacteroides sp. and Lactobacillus salivarius) were measured after growth in vitro and in vivo. The five strains differed in their activities with Clostridium sp. being the most active for beta-glucosidase, beta-glucuronidase and nitroreductase, and E. coli the most active producer of nitrate reductase. Enzyme activity in vivo tended to be higher than in vitro but there were instances where the comparative activities were reversed.
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PMID:The influence of the host on expression of intestinal microbial enzyme activities involved in metabolism of foreign compounds. 393 53

Rats, mice, and hamsters were fed iota-carrageenan incorporated in a fiber-free, purified diet for 30 days, and the activities of a number of cecal microbial enzymes were determined in vitro. Carrageenan treatment produced cecal enlargement in all species, yet significantly decreased the concentration of bacteria per gram of cecal content. Azoreductase, beta-glucosidase, beta-glucuronidase, nitrate reductase, and nitroreductase activities per gram of cecal content were significantly decreased in the rat, although less consistent effects were found in these enzymes in the mouse and hamster. beta-Glucuronidase and nitrate reductase functions were increased per gram of cecal contents in the hamster. The total activity per cecum of certain of these enzymes was modified by the concomitant cecal enlargement, yet total nitroreductase activity was significantly decreased in all three rodent species. iota-Carrageenan significantly decreased the concentration of enterobacteria, staphylococci, streptococci, lactobacilli, facultative anaerobes, and the total microscopic count in the rat cecum, but did not exert any effect on bacterial viability in vitro. Although having no effect on biliary IgA antibody concentration, iota- and kappa- carrageenan when present at 50 g/kg diet increased the agglutination response of the IgA specific for the hindgut microflora.
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PMID:Influence of dietary carrageenans on microbial biotransformation activities in the cecum of rodents and on gastrointestinal immune status in the rat. 404 88

The study of 52 strains of rapidly growing mycobacteria showed that Mycobacterium fortuitum and M. chelonei were clearly distinguished by the aid of seven key tests (nitrate reductase, iron uptake, beta-glucosidase, penicillinase, growth on fructose, resistance to pipemidic acid, and resistance to capreomycin) and by analysis of their respective mycolic acids. However, the subdivision of these species into M. fortuitum var. fortuitum and M. fortuitum var. peregrinum and M. chelonei subsp. chelonei and M. chelonei subsp. abscessus was not satisfactorily accomplished.
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PMID:Identification of Mycobacterium fortuitum and Mycobacterium chelonei. 619 Aug 37


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