The hydrolysis of urea by ureases of oral bacteria in dental plaque can cause a considerable increase in plaque pH, which can inhibit the development of dental caries. There is also indirect evidence that urea metabolism may promote the formation of calculus and that ammonia release from urea could exacerbate periodontal diseases. Actinomyces naeslundii, an early colonizer of the oral cavity an...

Proteus mirabilis, a cause of complicated urinary tract infection, produces urease, an essential virulence factor for this species. UreR, a member of the AraC/XylS family of transcriptional regulators, positively activates expression of the ure gene cluster in the presence of urea. To specifically evaluate the contribution of UreR to urease activity and virulence in the urinary tract, a ureR mu...

Helicobacter pylori is a human pathogen that infects over 50% of the population worldwide. It is the most important etiologic agent of gastroduodenal ulcers and malignancies. Helicobacter pylori urease enzyme is considered the main factor for the organism's colonization in the gastroduodenal mucosa. Hens immunized with the purified urease produce a highly specific anti-H. pylori urease immunogl...

Three laboratory-prepared urease reagents were compared with a commercial preparation supplied for routine use on the Beckman Blood Urea Nitrogen Analyzer. There were discrepancies in results for urea nitrogen among the four urease reagents when matching serum and the corresponding oxalate/fluoride treated plasma were compared as measured with the Beckman Analyzer and continuous-flow (AutoAnaly...

Urease and the cytotoxin VacA are two major virulence factors of the human pathogen Helicobacter pylori, which is responsible for severe gastroduodenal diseases. Diffusion of urea, the substrate of urease, into the stomach is critically required for the survival of infecting H. pylori. We now show that VacA increases the transepithelial flux of urea across model epithelia by inducing an unsatur...

Urease is the enzyme catalyzing the hydrolysis of urea into carbon dioxide and ammonia. This enzyme is substrate-specific, which means that the enzyme catalyzes the hydrolysis of urea only. This feature is a basic diagnostic criterion used in the determination of many bacteria species. Most of the methods utilized for detection of urease are based on analysis of its enzyme activity – the hydrol...

Eradication of Helicobacter pylori with currently available antibacterial agents is unsatisfactory due to the risk of side-effects and the emergence of resistance. The organism rapidly dies in vitro in the presence of urea at pH 6. When incubated in citrate buffer (pH 6) plus urea (10 mM) the five minute survival was 26% compared with 96% without urea and the survival progressively decreased wi...

We employed a urease-catalyzed reaction to gradually remove a high concentration of a chaotropic agent (urea) from a denatured protein solution and demonstrated that efficient protein refolding can be achieved by the urease-catalyzed reaction, without large-volume dilution.

Survival of Helicobacter pylori in acid depends on intrabacterial urease. This urease is a Ni(2+)-containing oligomeric heterodimer. Regulation of its activity and assembly is important for gastric habitation by this neutralophile. The gene complex encodes catalytic subunits (ureA/B), an acid-gated urea channel (ureI), and accessory assembly proteins (ureE-H). With the use of yeast two-hybrid a...

Dental caries results from prolonged plaque acidification that leads to the establishment of a cariogenic microflora and demineralization of the tooth. Urease enzymes of oral bacteria hydrolyze urea to ammonia, which can neutralize plaque acids. To begin to examine the relationship between plaque ureolytic activity and the incidence of dental caries, recombinant, ureolytic strains of Streptococ...