Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:6.3.4.6 (urease)
 7,490 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Previous studies from our laboratory have shown that struvite crystals form primarily as a result of urease-induced alkalinity and supersaturation. In vitro perfusion of struvite crystals with undersaturated urine caused crystal dissolution. The investigations reported herein demonstrate complete dissolution of human struvite urinary stones during 6 weeks of perfusion in vitro with undersaturated human urine. Human hydroxyapatite stones perfused similarly underwent only slight dissolution. A glycoprotein precipitated as the stones dissolved; the pathogenic significance of the glycoprotein is unknown.
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PMID:Dissolution of struvite urinary stones. Experimental studies in vitro. 125 28

The potential of Helicobacter pylori to degrade gastric mucus was examined. Colonies of H pylori cultured from antral mucosal biopsy specimens of patients with non-autoimmune gastritis were washed with sterile saline, passed through a sterilisation filter, and the filtrate examined for urease, protease, and mucolytic activity. The filtrate failed to hydrolyse bovine serum albumin, or to degrade stable mucus glycoprotein structures of high particle weight that had been separated from human gastric mucus on Sepharose 2B. The high particle weight mucus glycoprotein was, however, extensively degraded when incubated with H pylori filtrate (which possessed urease activity) in the presence of 2 M urea, to release fragments of Mr approximately 2 X 10(6). The high particle weight mucus glycoprotein was also broken down to a comparable extent when incubated with Jack bean urease in the presence of 2 M urea, or 1 M ammonium carbonate, or 40 mM carbonate-bicarbonate buffer (pH 8.7), but not when treated with 4 M urea alone, or Jack bean urease alone. These results indicate that the loss of high particle weight mucus glycoprotein in gastric mucus from patients with gastritis and gastric ulcers is unlikely to be due to the mucolytic action of an extra-cellular protease produced by H pylori, but it may result from the destabilising effects of a carbonate-bicarbonate buffer, generated at the mucosal surface when H pylori urease hydrolyses transuded plasma urea.
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PMID:Breakdown of gastric mucus in presence of Helicobacter pylori. 199 34

Occurrence of a protein controlling urease synthesis (PIUS) at the transcriptional level in the lichen Evernia prunastri has been previously reported (Perez-Urria & Vicente, Physiol Plant 65: 433-438, 1985; id. Endocyt C Res 3: 311-316, 1986). In this work it was found that 0.1 mM cycloheximide seems to inhibit PIUS synthesis when lichen thalli are incubated on PIUS inducer, L-arginine. PIUS has been purified and characterized by PAGE, electrofocusing and amino acid analysis. It is a glycoprotein containing a homopolymer of fructose bound to the protein. PIUS has been located in whole thallus and lichenized mycobiont but remains undetectable in cultured fungi. PIUS is only detected in photobiont cells when they are axenically cultured on arginine. Thus, it is postulated that PIUS could be synthesized by lichenized photobionts from which it moves to mycobionts where it inhibits the production of fungal urease.
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PMID:Algal partner regulates fungal urease in the lichen Evernia prunastri by producing a protein which inhibits urease synthesis. 249 82

Highly specific detection of human alpha 1-acid glycoprotein (AGP) and asialo-alpha 1-acid glycoprotein (asialo-AGP) was made possible by use of a sandwich immunoassay. The glycoproteins were sandwiched between biotinylated and fluoresceinated polyclonal rabbit anti-human AGP antibodies. Additionally, asialo-AGP could be distinctly detected, apart from AGP, via the formation of a heterosandwich immunoassay using biotinylated polyclonal rabbit anti-human AGP and the lectin, fluoresceinated ricin toxin. Streptavidin was added to the formed immunocomplexes and the immunocomplexes captured on a biotinylated nitrocellulose membrane. The signal generator, urease conjugate of an anti-fluorescein antibody, was then bound to the complex on the membrane. The rate of pH change under microvolume conditions (0.6 microliters) was monitored using a silicon chip-based, light addressable potentiometer sensor. Results indicated that AGP and asialo-AGP can be detected to the 2 pg level when two antibodies are used to form the immunocomplex. Asialo-AGP can be detected down to 250 pg when the heterosandwich immunoassay is used; this assay exhibited no response up to 10 ng for native AGP or asialofetuin. Both immunoassays can be used to quantify the level of AGP and asialo-AGP in solution. Although the assay presented is very specific for AGP, asialo-AGP and terminal galactose, it is readily adaptable for the detection of any glycoprotein and terminal carbohydrate (or branched structure) by use of a protein-specific antibody and various lectins.
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PMID:Detection of human asialo-alpha(1)-acid glycoprotein using a heterosandwich immunoassay in conjunction with the light addressable potentiometric sensor. 887 21

Paracoccidioides brasiliensis, the causative agent of paracoccidioidomycosis (PCM), was first isolated from armadillos from the Amazonian region where the mycosis is uncommon. In the present study, we report on the high incidence of PCM infection in armadillos from a hyperendemic region of the disease. Four nine-banded armadillos (Dasypus novemcinctus) were captured in the endemic area of Botucatu, Sao Paulo, Brazil, killed by manual cervical dislocation and autopsied under sterile conditions. Fragments of lung, spleen, liver, and mesenteric lymph nodes were processed for histology, cultured on Mycosel agar at 37 degrees C, and homogenized for inoculation into the testis and peritoneum of hamsters. The animals were killed from week 6 to week 20 postinoculation and fragments of liver, lung, spleen, testis, and lymph nodes were cultured on brain heart infusion agar at 37 degrees C. Paracoccidioides brasiliensis was isolated from three armadillos both by direct organ culture and from the liver, spleen, lung, and mesenteric lymph nodes of hamsters. In addition, one positive armadillo presented histologically proven PCM disease in a mesenteric lymph node. The three armadillos isolates (Pb-A1, Pb-A2, and Pb-A4) presented thermodependent dimorphism, urease activity, and casein assimilation, showed amplification of the gp43 gene, and were highly virulent in intratesticularly inoculated hamsters. The isolates expressed the gp43 glycoprotein, the immunodominant antigen of the fungus, and reacted with a pool of sera from PCM patients. Taken together, the present data confirm that armadillos are a natural reservoir of P. brasiliensis and demonstrate that the animal is a sylvan host to the fungus.
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PMID:Isolation of Paracoccidioides brasiliensis from armadillos (Dasypus noveminctus) captured in an endemic area of paracoccidioidomycosis. 957

Human renal dipeptidase is a membrane-bound glycoprotein hydrolyzing dipeptides and is involved in hydrolytic metabolism of penem and carbapenem beta-lactam antibiotics. The crystal structures of the saccharide-trimmed enzyme are determined as unliganded and inhibitor-liganded forms. They are informative for designing new antibiotics that are not hydrolyzed by this enzyme. The active site in each of the (alpha/beta)(8) barrel subunits of the homodimeric molecule is composed of binuclear zinc ions bridged by the Glu125 side-chain located at the bottom of the barrel, and it faces toward the microvillar membrane of a kidney tubule. A dipeptidyl moiety of the therapeutically used cilastatin inhibitor is fully accommodated in the active-site pocket, which is small enough for precise recognition of dipeptide substrates. The barrel and active-site architectures utilizing catalytic metal ions exhibit unexpected similarities to those of the murine adenosine deaminase and the catalytic domain of the bacterial urease.
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PMID:Crystal structure of human renal dipeptidase involved in beta-lactam hydrolysis. 1214 77

Concanavalin A, the lectin from Canavalia ensiformis, develops arginase activity depending on Mn(2+). The cation cannot be substituted by Ca(2+) which, in addition, inhibits Mn(2+)-supported activity. Fluorescein-labeled Concanavalin A is able to bind to the cell wall of algal cells recently isolated from Evernia prunastri and Xanthoria parietina thalli. This binding involves a ligand, probably a glycoprotein containing mannose, which can be isolated by affinity chromatography. Analysis by SDS-PAGE reveals that the ligand is a dimeric protein composed by two monomers of 54 and 48 kDa. This ligand shows to be different from the receptor for natural lichen lectins, previously identified as a polygalactosylated urease.
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PMID:Concanavalin A binds to a mannose-containing ligand in the cell wall of some lichen phycobionts. 1559 96

Coccidioides is a fungal respiratory pathogen of humans that can cause disease in both immunosuppressed and immunocompetent individuals. We describe here three mechanisms by which the pathogen survives in the hostile host environment: production of a dominant spherule outer wall glycoprotein (SOWgp) that modulates host immune response and results in compromised cell-mediated immunity to coccidioidal infection, depletion of SOWgp presentation on the surface of endospores, which prevents host recognition of the pathogen when the fungal cells are most vulnerable to phagocytic defenses, and induction of elevated production of host arginase I and coccidioidal urease, which contribute to tissue damage at sites of infection. Arginase I competes with inducible nitric oxide synthase (iNOS) in macrophages for the common substrate, L-arginine, and thereby reduces nitric oxide (NO) production and increases the synthesis of host orinithine and urea. Host-derived L-ornithine may promote pathogen growth and proliferation by providing a pool of the monoamine, which could be taken up and used for synthesis of polyamines via metabolic pathways of the parasitic cells. We have shown that high concentrations of Coccidioides- and host-derived urea at infection sites in the presence of urease produced and released by the pathogen, results in secretion of ammonia and contributes to alkalinization of the microenvironment. We propose that ammonia and enzymatically active urease released from spherules during the parasitic cycle of Coccidioides exacerbate the severity of coccidioidal infection by contributing to a compromised immune response to infection and damage of host tissue at foci of infection.
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PMID:Virulence mechanisms of coccidioides. 1751 66

Concanavalin A (ConA) is immobilized on a pre-activated chitosan microspheres, and then oriented immobilization of urease is carried out based on the strong interaction between ConA and glycoprotein. The optimum immobilization conditions are as follows: glutaraldehyde concentration is 3.5%, ConA concentration 1 mg/mL, ConA pH 7.0 and urease concentration 0.4 mg/mL. For orientedly immobilized urease, the highest activity was allowed at pH 5.0-6.0 and temperature 77 degrees C, and the Michaelis constant (Km) was disclosed to be 11.76 mmol/L by Lineweaver-Burk plot. Compared with the free urease and the randomly immobilized urease, the optimum pH of the orientedly immobilized urease becomes smaller and the pH domain wider. Orientedly immobilized urease presents higher temperature resistance, higher affinity to the substrate, and higher stability of operation.
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PMID:[Research on the orientedly immobilized urease via concanavalin A]. 1861 72

Many clinical investigations have suggested that Helicobacter pylori (H. pylori) infection might be associated with immune thrombocytopenic purpura (ITP), but its role in the pathogenesis of ITP is unsettled. In this study, we cultured H. pylori, produced recombinant H. pylori urease (ure) B, and then prepared monoclonal antibody (MoAb) against ureB, 1F11, both 1F11 and MoAb against human platelet glycoprotein (GP) IIIa, SZ21, could bind to the band of GP IIIa of normal platelet lysate, but not to that from a patient with Glanzmann thrombasthenia (GT) whose GP IIb-IIIa complex was absent. Flow cytometry showed that normal platelets were reacted with 1F11 and SZ21, while GT platelets were not. In immuno-radiometric assay, the binding of (125)I-labeled 1F11 to GP IIIa was higher than that to GP Ib, GP IIb, GP VI, and P-selectin. 1F11 could partly compete with SZ21 in a binding to platelet surface. In addition, 1F11 inhibited platelet aggregation induced by adenosine diphosphate, but had no effect on platelet P-selectin expression or Thromboxane B(2) production of platelets. These results indicate that H. pylori ureB antibody could cross-react with human platelet GP IIIa and partly inhibit platelet aggregation. UreB may be a crucial component of H. pylori involved in the pathogenesis of a subset of ITP.
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PMID:Cross-reaction of antibody against Helicobacter pylori urease B with platelet glycoprotein IIIa and its significance in the pathogenesis of immune thrombocytopenic purpura. 1918 77


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