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)

Flurofamide, a potent inhibitor of urease, at concentrations of 0.0007 to 0.001 mg/l inhibited the multiplication of three ureaplasma strains of human genital origin (one tetracycline-resistant) and two and three strains of marmoset genital and oral origin, respectively. However, a more than 1000-fold greater concentration of the drug was required to kill the organisms. Flurofamide did not inhibit the growth of arginine-hydrolysing or glucose-fermenting mycoplasmas, indicating its specificity for ureaplasmas. When it was given orally in a dose of 25 mg twice on one day and 25 mg on one further day to marmosets infected naturally with ureaplasmas in their throats, the organisms disappeared rapidly. The animals remained ureaplasma-free for 42 to 106 days, at which time they were successfully infected experimentally.
J Antimicrob Chemother 1984 Dec
PMID:The inhibitory effect of flurofamide on ureaplasmas and their elimination from marmosets by its use. 644 Aug 84

Providencia stuartii has emerged as a significant nosocomial urinary tract pathogen. An increase in the number of Providencia isolates from urine cultures prompted an investigation into the possibility of an outbreak due to this organism. A high proportion of patients studied had urinary devices. Four wards were screened at two time periods to ascertain the prevalence of Providencia stuartii in urine cultures. Biotype, serotype, antibiogram and plasmid content were determined for each Providencia isolate. Of 129 patients initially sampled 22.5% were found to harbor Providencia stuartii. Biotyping, serotyping and antibiograms indicated an epidemic strain was not present. Similar results were obtained when the wards were screened a second time, with 25.4% of urine cultures found to contain Providencia stuartii. By plasmid analysis the isolates could be grouped into one of ten profiles. A correlation could be made between urease activity and the presence of a large plasmid. No association however could be made between a particular plasmid profile and antibiogram. The data indicate that an epidemic strain of Providencia stuartii was not present. The source(s) of the endemic Providencia stuartii strains remain unknown.
Eur J Clin Microbiol 1984 Dec
PMID:Characterization of endemic Providencia stuartii isolates from patients with urinary devices. 652 19

Renacidin (10 per cent hemiacidrin) irrigation has been used in the management of renal struvite calculi in 25 patients. Of these patients 22 were free of stone after irrigation: 16 after dissolution of residual stone fragments postoperatively, 4 after prophylactic postoperative irrigation and 2 after primary, nonsurgical percutaneous dissolution. Recurrent urinary tract infections owing to the original urease-producing bacteria occurred in 14 per cent of these patients and recurrent nephrolithiasis occurred in 9 per cent during an average followup period of 66 months.
J Urol 1983 Dec
PMID:Hemiacidrin irrigation in the management of struvite calculi: long-term results. 664 80

Hyperammonemia was provoked in rats by urease injection over three days. Tryptophan transport into the forebrain measured by the bolus injection technique was increased in hyperammonemic rats in comparison with pairfed controls. The concentration of the large neutral aminoacids, of tryptophan and of 5-hydroxyindole acetic acid were increased in the forebrain and brainstem. Probenecid administration led to a significantly higher accumulation of 5-hydroxyindole acetic acid in the forebrain of hyperammonemic rats. Since liver function was not impaired the data indicate that hyperammonemia in absence of hepatic insufficiency alters the carrier function for large neutral aminoacids at the blood brain barrier.
Life Sci 1983 Dec 12
PMID:Increased tryptophan uptake into the brain in hyperammonemia. 664 6

Lenses produce both ammonia and urea, and a previous report suggested that bovine lenses contain a complete urea cycle capable of synthesizing urea from bicarbonate and ammonia. To determine whether lenses produce urea by a complete urea cycle or by arginase alone, intact lenses were cultured with [guanido-14C]-arginine or [14C]-bicarbonate. The [14C]-urea was volatilized to [14C]-CO2 by urease and collected in KOH. The cultured rat, bovine and human lenses produced [14C]-urea from [14C]-arginine; therefore lens arginase activity was also examined in homogenates of rat and human lenses. Rat lens homogenates had constant arginase activity for at least 2 hr at 37 degrees C, and activity increased linearly with the concentration of lens homogenate. Rat lens arginase had an apparent Vmax of approximately 13 nmol/hr/mg lens wet weight in lens homogenates and produced 4-6 nmol urea/hr/mg at 25 mM arginine. Human lens homogenates produced 1-5 nmol/hr/mg. In contrast, neither bovine nor rat lenses cultured with [14C]-bicarbonate produced detectable [14C]-urea, although label was incorporated into unidentified nonvolatile products. These products were shown by ion exchange chromatography and enzymatic assay to contain no detectable arginine or urea. It was concluded that although arginase activity is present, neither rat nor bovine lenses contain significant urea cycle activity. However, it is possible that arginase serves as a source of lens ornithine.
Exp Eye Res 1983 Dec
PMID:Urea formation in rat, bovine, and human lens. 666 5

The regions 5' proximal to many yeast tRNA genes exhibit a high frequency of DNA sequence polymorphisms. DNA sequence analysis of polymorphic variants of SUQ5, a tRNA Ser UCA gene, and SUP2, a tRNA Tyr gene, shows that in each case one sequence variant of the tRNA gene is 346 base pairs longer than the other. The longer variants appear to have arisen from the shorter ones by the insertion of nearly identical copies of a 341-base pair sigma element into a site 16 base pairs upstream from the 5' ends of the tRNA-coding regions. The sequences of the two copies of the sigma element differ at only five positions. The element has a number of properties that are typical of many transposable elements: (i) there is a perfect eight-base-pair inverted repeat at its ends, (ii) these ends are flanked by a five-base-pair direct repeat of a sequence that occurs only once in the target DNA, (iii) there are approximately 20 copies of the element in the yeast genome, and (iv) there is considerable strain-to-strain variation in the sizes of the restriction fragments on which these copies lie. The presence of the sigma element has no gross effect on the phenotype of a SUP2 ochre suppressor. Analysis of the SUQ5 and SUP2 sequences favors the hypothesis that sigma is a transposable element with a novel type of insertion specificity, which is primarily based on the presence of a tRNA-coding region a fixed distance from the insertion site, rather than on the immediate target sequences.
Proc Natl Acad Sci U S A 1982 Dec
PMID:Insertion of a repetitive element at the same position in the 5'-flanking regions of two dissimilar yeast tRNA genes. 676 Feb 1

A highly sensitive radiochemical assay used to measure the synthesis and regulation of the product of the argH gene, argininosuccinase, in an Escherichia coli system in vitro is described. With L-[guanidino-14C]argininosuccinic acid as a substrate, and in the presence of excess arginase and urease, 14CO2 is collected in a simply designed micro-vessel. With this method less than 1 nmol of product can be measured in the presence of various concentrations of L-arginine.
Biochem J 1982 Dec 01
PMID:The determination by radiochemical assay of argininosuccinase produced in an Escherichia coli system in vitro. 676 7

Acetamide and N-methylurea have been shown for the first time to be substrates for jack bean urease. In the enzymatic hydrolysis of urea, formamide, acetamide, and N-methylurea at pH 7.0 and 38 degrees C, kcat has the values 5870, 85, 0.55, and 0.075 s-1, respectively. The urease-catalyzed hydrolysis of all these substrates involves the active-site nickel ion(s). Enzymatic hydrolysis of the following compounds could not be detected: phenyl formate, p-nitroformanilide, trifluoroacetamide, p-nitrophenyl carbamate, thiourea, and O-methylisouronium ion. In the enzymatic hydrolysis of urea, the pH dependence of kcat between pH 3.4 and 7.8 indicates that at least two prototropic forms are active. Enzymatic hydrolysis of urea in the presence of methanol gave no detectable methyl carbamate. A mechanism of action for urease is proposed which involves initially an O-bonded complex between urea and an active-site Ni2+ ion and subsequently an O-bonded carbamato-enzyme intermediate.
Can J Biochem 1980 Dec
PMID:Jack bean urease (EC 3.5.1.5). V. On the mechanism of action of urease on urea, formamide, acetamide, N-methylurea, and related compounds. 678 53

Dielectric heating at frequencies of 42 and 2450 MHz was applied to whole soybeans of natural moisture content for varies exposure times. The minimum energy absorbed (MEA) was calculated from moisture-loss and temperature-elevation data. Biochemical analyses were performed to determine protein dispersibility index (PDI), nitrogen solubility index (NSI), and trypsin-inhibitor, urease, lipoxygenase, and peroxidase activities. Because the heating rates were different at the two frequencies for the power levels used, plots of the biochemical properties against temperature of exposure time showed an apparent frequency dependence. This dependence on frequency disappeared, however, when MEA was substituted as the independent variable. Chemical analyses revealed that dielectric heating of soybeans at natural moisture levels should be as effective as conventional steam toasting in reducing trypsin-inhibitor activity. PDI and NSI, but not urease, were suitable indicators of trypsin-inhibitor inactivation by dielectric heating. Lipoxygenase was completely inactivated by the dielectric-heating treatments that gave suitable trypsin-inhibitor inactivation, but peroxidase activity remained relatively high, offering possible advantages for bleaching and improved soy product color.
J Microw Power 1981 Dec
PMID:Effects of 42- and 2450-MHz dielectric heating on nutrition-related properties of soybeans. 692 Apr 15

After a brief review of the methods for determination of urea by continuous flow analyzers, a method is described based on the urease splitting of urea followed by NH3 reaction with alfa-ketoglutarate + NADH2 catalysed by GLDH. The method has been applied to continuous flow analyzers and seems to be promising.
Quad Sclavo Diagn 1982 Dec
PMID:[Review of the methods of determination of blood urea with continuous-flow analyzers and a proposal of a completely enzymatic UV method for urea by a continuous-flow analyzer]. 718 46


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