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:3.5.1.5 (urease)
7,257 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In order to clarify the mechanism of the anti-Helicobacter pylori action of ecabet sodium (ecabet), a locally acting antiulcer drug, we evaluated the effects of ecabet on H. pylori urease activity in vitro. H. pylori was cultured and a crude preparation of urease was made. Urea-dependent survival of H. pylori at acid pH was significantly inhibited by ecabet. The urease activity of intact cells and a crude enzyme preparation from H. pylori had two pH optima: pH 4.5-5.0 and 8.0. Ecabet (1-4 mg/ml) concentration dependently inhibited the urease activity of both preparations at pH 5.0, but there was no inhibition at pH 8.0. The enzyme activity was inhibited by ecabet gradually and was not restored by dilution, in contrast to the inhibition elicited by benzohydroxamic acid, a specific and reversible urease inhibitor. These results suggest that irreversible inhibition of H. pylori urease activity contributes to the anti-H. pylori action of ecabet.
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PMID:Ecabet sodium, a locally acting antiulcer drug, inhibits urease activity of Helicobacter pylori. 960 Jun 37

Helicobacter pylori exhibits chemotactic responses to urea, flurofamide, acetohydroxamic acid, and sodium bicarbonate. In buffer, the chemotactic activities of a urease-positive strain were higher than those of the isogenic urease-negative strain. Moreover, the chemotactic activities of the urease-positive strain were increased in a viscous solution containing 3% polyvinylpyrrolidone, whereas those of the urease-negative mutant were not. These results are in accordance with the fact that the mutant strain did not show swarming in motility agar regardless of having flagella. Incubation of the wild-type strain with flurofamide resulted in partial inhibition of the chemotactic activities in the viscous solution. In addition, incubation with acetohydroxamic acid, a low-molecular-weight, diffusible urease inhibitor, resulted in complete loss of chemotactic activity in the viscous solution. The inhibition of the chemotactic activity by urease inhibitors paralleled the inhibition of urease. The chemotactic activity of H. pylori was also inhibited by the proton carrier carbonyl cyanide m-chlorophenylhydrazone, showing that H. pylori utilizes proton motive force for motility. These results indicate that cytoplasmic urease plays an important role in the chemotactic motility of H. pylori under a condition that mimics the ecological niche of the bacterium, the gastric mucous layer.
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PMID:Urease plays an important role in the chemotactic motility of Helicobacter pylori in a viscous environment. 974 86

Helicobacter pylori has adapted to a very specialized niche; namely, the highly acidic, viscous, and somewhat anaerobic gastric mucus of humans. The enzyme urease is essential for colonization of the stomach, as it provides protection against gastric acidity. A spiral morphology as well as sheathed flagella have been claimed to give the bacteria an advantage in colonizing mucus. Wild type strain of H. pylori and its isogenic urease-negative mutant showed a chemotactic response to urea, flurofamide (a potent urease inhibitor), sodium ion, and bicarbonate ion. These chemotactic responses are also observed in the viscous environment. Thus, it appears that H. pylori has chemotactic movement that is independent of urease activity. The chemotactic response was inhibited by carbonyl cyanide m-chlorophenylhydrazone (CCCP), a potent H+ pump inhibitor, but not by Na+ pump-inhibiting amiloride, suggesting this response is forced by H+-driven flagellar movement. Since urea and sodium bicarbonate are secreted from the gastric epithelial surface, this chemotactic response may contribute to the colonization by H. pylori and the persistence of its infection.
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PMID:Chemotaxis of Helicobacter pylori: a urease-independent response. 984 7

Urease from seeds of the water melon was found to be inhibited by various salts of sodium. Sodium fluoride strongly inhibited the activity in the low urea concentration range. The enzyme was also inhibited by a high concentration of urea which was completely abolished in the presence of 10 mM sodium fluoride. Time-dependent inactivation of urease with iodoacetic acid, N-ethylmaleimide and p-hydroxymercuribenzoate exhibited biphasic kinetics in which half of the initial activity was lost in the fast phase and the remainder in a slow phase. Each phase exhibited first-order kinetics. These observations are suggestive of the existence of half-and-half distribution of sites.
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PMID:A study of inhibition of urease from seeds of the water melon (Citrullus vulgaris). 987 15

Three hundred thirty-three patient (116 gastric ulcer, 119 duodenal ulcer, 98 gastritis) who were successfully eradicated were enrolled in the study of H. pylori recurrence rate. H. pylori status was determined by histology, rapid urease test, 13C-urea breath test. The mean of the follow-up period was 13.3 months (2-56 months), and 15 patients showed negative to positive conversion of H. pylori. The recurrence rate was 4.4% for one year and 8.3% for two years using Kaplan-Meier analysis. Second eradication therapy after initial failure is another concern. Nineteen patients were assigned to receive an 1-week new triple therapy (clarithromycin, metronidazole and PPI), in whom a 2-week course of dual therapy (amoxicillin plus PPI) failed (group1). Another 15 patients in whom the 1-week new triple therapy failed were switched to the 2-week course of dual therapy plus ecabet sodium (group2). H. pylori was eradicated in 84.2% (16/19) of patients in group1 and 86.7% (13/15) in group2.
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PMID:[Recurrence rate of H. pylori after successful eradication and second eradication therapy after initial failure of treatment]. 1003 47

We have previously characterized an exocellular serine-thiol proteinase activity in Paracoccidioides brasiliensis, using as substrates peptides analogous of the internally quenched fluorogenic peptide Abz-MKRLTL-EDDnp. In this communication, detection of maximal proteinase activity in the culture supernatant fluids followed the abrupt increase in the medium pH, owing to the accumulation of ammonia generated by urease activity. Culture supernatant fluids collected at the peak of proteinase activity against Abz-MRKLTL-EDDnp were able to cleave components of the basal membrane of the extracellular matrix (EM), including laminin, fibronectin, collagen type IV and proteoglycans, and the proteolytic activity was selectively inhibited both by PMSF and p-HMB (sodium 7-hydroxymercuribenzoate), which are also specific inhibitors of the serine-thiol proteinase. Human collagen I, bovine fibrinogen, human immunoglobulin G, BSA or P. brasiliensis gp43 were resistant to proteolysis. The kinetics of appearance of the proteinase activity against EM substrates coincided with that of proteolysis of Abz-MKRLTL-EDDnp. Moreover, chromatographic fractions of culture supernatants containing the serine-thiol proteinase at high specific activity were also active against EM substrates. These data suggest the involvement of this enzyme activity in the degradation of the basement membrane, which is the first step for fungal tissue invasion.
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PMID:Exocellular proteolytic activity of Paracoccidioides brasiliensis: cleavage of components associated with the basement membrane. 1007 6

It has been shown that urea in fermented beverages and foods can serve as a precursor of ethylcarbamate, a potential carcinogen, and acid urease is an effective agent for removing urea in such products. We describe herein the purification and characterization of a novel acid urease from Arthrobacter mobilis SAM 0752 and show its unique application for the removal of urea from fermented beverages using the Japanese rice wine, sake, as an example. The purified acid urease showed an optimum pH for activity at pH 4.2. The enzyme exhibited an apparent K(m) for urea of 3.0 mM and a Vmax of 2370 mumol of urea per mg and min at 37 degrees C and pH 4.2. Gel permeation chromatographic and sodium dodecyl sulfate gel electrophoretic analyses showed that the enzyme has an apparent native molecular weight (M(r)) of 290,000 and consisted of three types of subunit proteins (M(r), 67,000, 16,600, 14,100) denoted by alpha, beta, and gamma. The most probable stoichiometry of the subunits was estimated to be alpha: beta: gamma = 1:1:1, suggesting the enzyme subunit structure of (alpha beta gamma)3. The enzyme also existed as an aggregated form with an M(r) of 580,000. The purified enzyme contained 2 g-atom of nickel per alpha beta gamma unit of the enzyme. Enzyme activity was inhibited by acetohydroxamic acid, HgCl2, and CuCl2. The isoelectric point of the native enzyme was estimated by gel electrofocusing to be 6.8. Urea (50 ppm), which was exogenously added to sake (pH 4.4, 17 +/- 1% (v/v) ethanol), was completely decomposed by incubation with the enzyme (0.09 U ml-1) at 15 degrees C for 13 days. The enzyme was unstable at temperatures higher than 65 degrees C and pHs lower than 4, and was completely inactivated under the conditions of a pasteurization step involved in the traditional sake-making processes. These results indicate that the enzyme is applicable to the elimination of urea in fermented beverages with minimal modification to the conventional process.
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PMID:Purification, characterization, and application of an acid urease from Arthrobacter mobilis. 1019 59

Helicobacter pylori colonizes the human gastric mucosa and produces large amounts of urease. The enzyme was extracted from the bacteria by distilled water and purified by gel-permeation (Sephacryl S-300), anion-exchange chromatography (Mono Q) and a second gel-permeation (Superdex 200). Urease enzyme activity was detected with a spectrophotometic assay based on phenol red. The optimal pH for anion-exchange was 6.9. The recovery of urease was 55-75%, purity 93-98% and the overall protein recovery 0.8-1.4%. The urease in the final extract still had enzymatic activity and showed the typical subunits of Mr 66000 and Mr 30000 when subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis.
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PMID:Purification of surface-associated urease from Helicobacter pylori. 1068 Oct 57

The "24-HOUR BATH" is an apparatus which circulates the bath water, keeps it clean and warm, and makes it possible to take a bath at any time during the day or night. It consists of apparatus for cleaning (sponge or mesh filter and filter material), heating (ceramic heater), and sterilizing (UV lamp). Recently, three cases of skin disease due to M. avium infection in private homes, in which "24-HOUR BATH" water was suspected to be the source of infection, have been reported. We attempted to isolate M. avium complex from the water (32 specimens), sponge filter (29 specimens), and filter material (32 specimens) of the "24-HOUR BATH". One hundred-ml samples of bath water, and 50-ml samples of rinse from a sponge filter or filter material were centrifuged at 3000 rpm for 20 min. Sediment was suspended in distilled water and a smear was prepared, and then digested and decontaminated with 2% sodium hydroxide. The processed specimens were cultured on 2% Ogawa medium containing ofloxacin (1 microgram/ml) and ethambutol (2.5 micrograms/ml) for 8 weeks at 37 degrees C. Positive smears were 3 (9.4%), 25 (86.2%) and 25 (78.1%) specimens from the water, sponge and filter material, respectively. A few bacterial clumps were observed, especially in the sponge specimens. The number of positive culture was 5 (15.6%), 24 (82.8%) and 25 (78.1%) from the water, sponge and filter material, respectively. Among them the number of Runyon's Group III-positive cultures was 5 (100%), 22 (91.7%) and 20 (80%) in the water, sponge, and filter material specimens, respectively. In most cases, cultures were positive for both the sponge and filter material specimens. All of the Group III mycobacteria were smooth, grew at 28, 37, 42, and 45 degrees C, negative for niacin, nitrate reductase, semiquantitative catalase, urease and Tween80 hydrolysis, and positive for 68 degrees C catalase. All of the strains reacted with M. avium complex AccuProbe and M. avium AccuProbe, but none of the strains reacted with M. intracellulare AccuProbe. Therefore, all the Group III isolates were identified as M. avium by the culture, biochemical and genetical characteristics.
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PMID:[Isolation of Mycobacterium avium complex from the "24-hour bath"]. 1068 14

Urease was purified from leaves of mulberry (Morus alba, L.) by ammonium sulfate fractionation, acetone fractionation and sequential column chromatography including Q-Sepharose HP, Phenyl-Sepharose HP, Superdex 200 HR and Mono Q. The enzyme was purified 5700-fold to apparent homogeneity with a recovery of 3.6%. The molecular mass of the enzyme was determined to be 90.5 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis and 175 kDa by gel filtration, indicating that the enzyme was a homodimer. In the western blot analysis, 90.5 kDa subunit of the mulberry leaf urease cross-reacted with antiserum raised against jack bean seed urease. The N-terminal sequence of the first 20 residues of the enzyme revealed that it has a high similarity (80-90%) to ureases from other plant sources, suggesting that the mulberry leaf urease is closely related to other plant ureases. However, the mulberry leaf enzyme showed an optimum pH for activity of 9.0, while the optimum pH of most ureases isolated from plants and bacterial is neutral. In addition, the K(m) value for urea was 0.16 mM, which is lower than those of ureases from other sources. It is also proposed that urease activity ingested by browsing silkworm releases ammonia that is subsequently used in silkworm protein synthesis.
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PMID:Purification and properties of urease from the leaf of mulberry, Morus alba. 1070 52


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