The role of the periplasmic -carbonic anhydrase ( -CA) (HP1186) in acid acclimation of Helicobacter pylori was investigated. Urease and urea influx through UreI have been shown to be essential for gastric colonization and for acid survival in vitro. Intrabacterial urease generation of NH3 has a major role in regulation of periplasmic pH and inner membrane potential under acidic conditions, allo...

R. G. Canti [1916] bas used the hypobromite method for obtaining approximate values for the amount of urea in the cerebro-spinal fluid of patients suffering from a variety of diseases. Being desirous of controlling this method by others more reliable he asked R. L. M. Wallis to determine the urea by the urease method in some cases, and G. Graham by the Folin method in others, and the writer to ...

In plants, urea derives either from root uptake or protein degradation. Although large quantities of urea are released during senescence, urea is mainly seen as a short-lived nitrogen (N) catabolite serving urease-mediated hydrolysis to ammonium. Here, we investigated the roles of DUR3 and of urea in N remobilization. During natural leaf senescence urea concentrations and DUR3 transcript levels...

HOUPT, T. RICHARD, AND KATHERINE A. HOUPT. Transfer of urea nitro,gen across the rumen wall. Am. J. Physiol. 2 1 /t(6) : 1296-1303. 1968.-Net movement of urea N across the wall of Pavlov-type rumen pouches was measured in three goats and one sheep as urea concentration difference between pouch and blood was varied. When urease activity of the rumen epitheliurn was depressed by vigorous rinsing ...

Proteus mirabilis urease, a nickel-containing enzyme, has been established as a critical virulence determinant in urinary tract infection. An amino acid sequence (residues 308 to 327: TVDEHLDMLMVCHHLDPSIP) within the large urease subunit, UreC, is highly conserved for every urease examined thus far and has been suggested to reside within the enzyme active site. Histidine residues have been post...

Cultures of Escherichia coli B and K-12 produce urea during growth in minimal medium. Results of isotopic labeling experiments were consistent with the sole source of urea being from the conversion of arginine to putrescine. Since E. coli itself has no demonstrable urease activity, the rate of urea production is a measure of the flux through the arginine to putrescine pathway.

Urease is an enzyme of wide distribution as evidenced by the fact that some 200 species of bacteria, as well as higher plants and animals have been found to possess it (Sumner and Somers, 1953). Pasteur and Miguel were reported to have isolated "urobacilli" from air, soil, and sewage (Cooke and Keith, 1927). Subsequently, the enzyme was found in many soil and intestinal bacteria (Gibson, 1934; ...

BACKGROUND AND PURPOSE (13)C-urea may be a suitable marker to assess the in vivo fate of colon-targeted dosage forms given by mouth. We postulated that release in the colon (urease-rich segment) of (13)C-urea from colon-targeted capsules would lead to fermentation of (13)C-urea by bacterial ureases into (13)CO(2). Subsequent absorption into the blood and circulation would lead to detectable (13...

Early studies of a ureB mutant derivative of Helicobacter pylori had suggested that urease is needed for motility and that urease action helps energize flagellar rotation. Here we report experiments showing that motility is unaffected by deletion of ureA and ureB (urease genes) or by inactivation of ureB alone, especially if H. pylori strains used as recipients for transformation with mutant al...