Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.5.1.5 (urease)
 7,257 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Analysis of heat stability of urease in extracts of 24 revertants, six for each of four ure loci, revealed that at least one revertant for each locus had a heat stability about one-third that of wild type. Similar results were obtained with urease formed by interallelic complementation at the ure-2 and ure-4 loci, but interallelic complementation at the ure-1 and ure-3 loci produced insufficient urease activity for analysis. The data are interpreted to suggest, as a tentative model, a structural function for each of the four ure loci.
Mol Gen Genet 1978 Oct 24
PMID:Reversion and interallelic complementation at four urease loci in Neurospora crassa. 15 55

Urease activity in the sheep rumen varied with the diet of the sheep, but appeared to be largely or entirely present in the small bacterial fraction. Screening of over 1000 strains of rumen bacteria isolated on different media showed that urease activity was apparently confined to species of Staphylococcus, Lactobacillus casei var. casei and Klebsiella aerogenes. Consideration of the numbers in which these occurred and their activities suggested that the bacteria could not be responsible for the total rumen urease activity. By enrichment culture a ureolytic strain of Streptococcus faecium was isolated. This had a higher urease activity than the other bacteria and occurred in higher numbers in the rumen. It could live with other bacteria in the rumen of a gnotobiotic lamb in numbers, and with a urease activity, comparable with those in the normal sheep rumen. The other properties of the bacterium also suggested that it would grow and produce urease in the rumen, but was unlikely to retain its urease activity after isolation. It was concluded that this bacterium was the main source of rumen urease in roughage-fed, and probably other, sheep.
J Gen Microbiol 1976 Jan
PMID:Urease activity in the rumen of sheep and the isolation of ureolytic bacteria. 81 52

A chemically-defined medium was developed which supported growth of Streptococcus faecium and permitted synthesis of urease. This streptococcus cannot utilize ammonia and needs a complex medium, but its requirements are probably provided in the rumen. The specific activity of urease was inversely related to growth and in no medium was there high growth and high urease activity. Anaerobic culture and the presence of urea in the medium were essential for urease activity, but not for growth.
J Gen Microbiol 1976 Dec
PMID:A chemically-defined medium for the growth of a ureolytic strain of Streptococcus faecium. 103 71

A strain of Streptococcus faecium from the sheep rumen showed spontaneous loss of urease activity when subcultured at the normal rumen temperature of 38 degrees C, although in mixed cultures in vivo or in vitro loss of urease was not apparent. The rate of loss of urease in pure cultures was increased at incubation temperatures above 38 degrees C, but loss was never complete. However, at temperatures below 38 degrees C loss was greater, and at 22 or 18 degrees C the urease was completely eliminated. Incubation with sodium dodecyl sulphate (0-002%) or ethidium bromide (2-5 X 10(-5)M) caused complete loss of urease activity. The urease activity was also eliminated when the streptococcus was grown aerobically, and this loss of activity was irreversible. It is suggested that the urease activity is controlled by a plasmid gene and that aeration, low growth temperature and chemical agents 'cure' the streptococcus of the plasmid. Attempts to demonstrate the presence of covalently closed circular extrachromosomal DNA by caesium chloride-ethidium bromide equilibrium density-gradient centrifugation were unsuccessful.
J Gen Microbiol 1976 Jan
PMID:The elimination of urease activity in Streptococcus faecium as evidence for plasmid-coded urease. 110 85

Estimates were made of the numbers of viable bacteria in the rumens of sheep receiving different rations. Representative colonies were isolated and tested for urease production. Some urease-positive isolates were characterized and identified. The ureolytic activities of the urease-producing isolates were determined and compared with the activity of rumen fluid. The rations fed to the sheep did not exert a significant influence on the relative numbers of the urease-producting organisms in the rumen. No obligately anaerobic ureolytic bacteria were found. All urease-positive isolates were facultatively anaerobic, Gram-positive, catalase-positive cocci. Out of ten isolates, nine were identified as Staphylococcus saprophyticus and one as Micrococcus varians. The total urease activity of the different isolates based on the lowest numbers in which they were present in the rumen, compared favourably with the urease activity of rumen fluid. The facultatively anaerobic Gram-positive cocci were probably responsible for a large proportion of the urease activity of the rumen fluid. Conditions prevailing in the rumen were found to be conducive to urease production by the isolates tested.
J Gen Microbiol 1975 Dec
PMID:Ureolytic bacteria in sheep rumen. 123 88

The urease of Helicobacter pylori (formerly Campylobacter pylori) has been partly purified by fast protein liquid chromatography. This material contained 10 nm doughnut-like structures when examined by electron microscopy and comprised three major polypeptides (61 kDa, 56 kDa and 28 kDa). Only two of these polypeptides (61 kDa and 28 kDa) were observed in urease-containing material isolated by preparative non-denatured PAGE. Monoclonal antibodies (mAbs) were produced which were directed against two of these polypeptides (56 kDa and 28 kDa). Only mAbs directed against the 28 kDa polypeptide inhibited or captured urease activity. These results suggest that the 56 kDa polypeptide is not essential for enzyme activity. Anti-urease mAbs were used in an indirect immunogold technique to localize the enzyme at the ultrastructural level. In both prefixed bacteria and ultrathin cryosectioned bacteria the enzyme was located on the cell surface and in material apparently shed from that surface.
J Gen Microbiol 1990 Oct
PMID:Investigation of the structure and localization of the urease of Helicobacter pylori using monoclonal antibodies. 226 72

The urease from Ureaplasma urealyticum (serotype 8) has been purified by immuno-affinity column chromatography. Two active nickel-containing forms of the enzyme were demonstrated by non-denaturing electrophoretic analysis and a single active peak of apparent molecular mass 190 kDa was shown by FPLC. Total inactivation and denaturation of the enzyme to give three subunit polypeptides (one of 72 kDa containing nickel, one of 14 kDa and one of 11 kDa) was achieved by treatment with SDS and boiling. Densitometry suggested that the active enzyme contains equimolar ratios of the three subunits and hence is a hexamer. The enzyme displayed a pH optimum of 6.9 and pI values were determined. Storage of the purified enzyme at -70 degrees C followed by thawing to 20 degrees C caused a partial breakdown to inactive subunits. Anti-urease monoclonal antibodies bound both to the active enzyme and to the inactive 72 kDa subunit, and the antibodies cross-reacted with ureases from all of the other human serotypes. Competition assays with the antibodies revealed four distinct epitopes of the enzyme, all distinct from its active site.
J Gen Microbiol 1989 Feb
PMID:The urease of Ureaplasma urealyticum. 248 31

The levels of several enzymes involved in assimilation of different nitrogen compounds were investigated in Streptomyces clavuligerus in relation to the nitrogen source supplied to the cultures. Threonine dehydratase, serine dehydratase, proline dehydrogenase, histidase and urocanase were not decreased in the presence of ammonium. The latter two enzymes were induced by histidine in the culture medium, while proline dehydrogenase was induced by proline. Glutamine synthetase, urease and ornithine aminotransferase levels were higher with poor nitrogen sources and were repressed by ammonium. Arginase was induced by arginine and repressed by ammonium. Glutamine synthetase was rapidly inactivated upon addition of ammonium to the culture, and could be reactivated in vitro by treatment with snake venom phosphodiesterase, which suggested that adenylylation is involved in the inactivation. Three previously isolated mutants with abnormal glutamine synthetase activities showed pleiotropic effects on urease formation. All these data point to a mechanism controlling preferential utilization of some nitrogen sources in this species.
J Gen Microbiol 1989 Sep
PMID:Regulation of nitrogen catabolic enzymes in Streptomyces clavuligerus. 257 37

Two screening methods for isolation of mutants of Streptomyces clavuligerus with altered control of nitrogen metabolism enzymes are described. Thirty-eight prototrophic mutants with simultaneous deregulation of urease and glutamine synthetase were isolated. Nine mutants were examined in more detail and they also showed deregulated formation of arginase and ornithine aminotransferase. Different patterns of altered control of all four enzymes were observed. Inactivation of glutamine synthetase after ammonium shock took place to different extents in these nine strains, and seven of them had a thermosensitive glutamine synthetase activity. It is concluded that a system of nitrogen control, in which glutamine synthetase has a key role, is present in S. clavuligerus. Cephalosporin production was depressed by ammonium in all the mutants, irrespective of the alterations in nitrogen control of primary metabolism.
J Gen Microbiol 1989 Sep
PMID:Isolation and characterization of nitrogen-deregulated mutants of Streptomyces clavuligerus. 257 38

Strongly catalase-positive Gram-negative anaerobic rods were isolated from approximately half of all intra-abdominal specimens received from patients with gangrenous and perforated appendicitis, and subsequently also from normal faecal specimens. The organism was originally detected on Bacteroides-bile-aesculin (BBE) agar, and grew slowly on non-selective anaerobic media containing blood. It was stimulated by bile and differed from other known genera by being urease- and catalase-positive, and by reducing nitrate. It did not reduce sulphate. Other anaerobic Gram-negative rods showed no homology by DNA dot-blot hybridization. The thermal melting profile of chromosomal DNA showed 39-40 mol% G + C. The whole-cell fatty acid methyl ester profile included cyclic and branched long-chain acids, and differed from those of all other anaerobes that have been tested. beta-Lactamase was not detected. The name Bilophila wadsworthia gen. nov., sp. nov. is proposed for this organism.
J Gen Microbiol 1989 Dec
PMID:Bilophila wadsworthia, gen. nov. and sp. nov., a unique gram-negative anaerobic rod recovered from appendicitis specimens and human faeces. 263 63


1 2 3 4 Next >>