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)

Under the term "non-calcium nephrolithiasis", three types of renal stone formation are considered. (1) Infected nephrolithiasis, which is due to bacteriological ureolysis. Its treatment includes lowering of oversaturation by antibiotics, urease inhibition and/or acidification of the urine; lowering of crystallization by eradicating concomitant infections caused by non-ureolytic organisms; prevention of crystal adherence by exogenous glycosaminoglycans, and prevention of bacterial adherence by glycolipids. (2) Uric acid lithiasis is defined on physico-chemical and physiopathological grounds. Medical treatment consists of increasing water intake, reducing puric acid intake, alkalinizing the urine inhibiting xanthine-oxidase. (3) Cystinuria is described as a nephrolithogenic proximal tubulopathy. Medical treatment includes reduction of urinary cystine concentration by a strong increase of water intake; reduction of urinary cystine excretion by diet and increase of cystine solubility by urinary alkalinization or administration of some thiol compounds.
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PMID:[Physiopathology, etiology and medical treatment of non-calcium lithiasis]. 178 96

Uric acid, but not xanthine, was degraded by gram-positive catalase-producing cocci and diphtheroids which represented the two predominant human autochthonous skin bacteria. The proportions of uricolytic cocci and diphtheroids varied with the cutaneous site sampled. Uric acid and allantoin were not utilized by cocci or diphtheroids as sole sources of nitrogen. Uric acid appeared to act only as a secondary substrate for the gram-positive bacteria. Cutaneous cocci are known to be ureolytic but few diphtheroids had urease activity. Urea and ammonium nitrogen were not utilized as sole nitrogen sources by cocci, but some diphtheroids used these compounds for nitrogen. The majority of the cocci and diphtheroids were nutritionally fastidious and required amino-nitrogen for growth. In addition, some strains required vitamins and other unidentified metabolites found in yeast extract. These requirements were partially related to the cutaneous site from which the cocci or diphtheroids were isolated. Certain gram-negative bacilli degraded uric acid and utilized urate or its degradation products as nitrogen sources.
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PMID:Nitrogen requirements and uricolytic activity of cutaneous bacteria. 491 42

In fat-degrading tissues of seedlings of seven different plant species examined, uricase activity (urate:O(2) oxidoreductase, EC 1.7.33) was associated with particulate fractions. After equilibrium density centrifugation on sucrose density gradients the enzyme activity was recovered in the glyoxysomal band (density: 1.25 grams per cubic centimeter). Allantoinase is also present in glyoxysomes but, equally, in the proplastid region (density: 1.22 grams per cubic centimeter). Xanthine oxidase, xanthine dehydrogenase, allantoicase, and urease were not detected in glyoxysomes from castor bean endosperm. Uricase in these particles shows its maximal activity at pH 8.9. The apparent K(m) is 7.4 mum. Urate concentrations greater than 120 mum as well as certain other purine compounds inhibit the enzyme. Cyanide at a concentration of 10 mum is a potent inhibitor. 2,6-Dichlorophenolindophenol did not substitute for oxygen as electron acceptor.
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PMID:Uricase and allantoinase in glyoxysomes. 1665 4

Degradation of purines to uric acid is generally conserved among organisms, however, the end product of uric acid degradation varies from species to species depending on the presence of active catabolic enzymes. In humans, most higher primates and birds, the urate oxidase gene is non-functional and hence uric acid is not further broken down. Uric acid in human blood plasma serves as an antioxidant and an immune enhancer; conversely, excessive amounts cause the common affliction gout. In contrast, uric acid is completely degraded to ammonia in most fungi. Currently, relatively little is known about uric acid catabolism in the fungal pathogen Cryptococcus neoformans even though this yeast is commonly isolated from uric acid-rich pigeon guano. In addition, uric acid utilization enhances the production of the cryptococcal virulence factors capsule and urease, and may potentially modulate the host immune response during infection. Based on these important observations, we employed both Agrobacterium-mediated insertional mutagenesis and bioinformatics to predict all the uric acid catabolic enzyme-encoding genes in the H99 genome. The candidate C. neoformans uric acid catabolic genes identified were named: URO1 (urate oxidase), URO2 (HIU hydrolase), URO3 (OHCU decarboxylase), DAL1 (allantoinase), DAL2,3,3 (allantoicase-ureidoglycolate hydrolase fusion protein), and URE1 (urease). All six ORFs were then deleted via homologous recombination; assaying of the deletion mutants' ability to assimilate uric acid and its pathway intermediates as the sole nitrogen source validated their enzymatic functions. While Uro1, Uro2, Uro3, Dal1 and Dal2,3,3 were demonstrated to be dispensable for virulence, the significance of using a modified animal model system of cryptococcosis for improved mimicking of human pathogenicity is discussed.
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PMID:Characterization of the complete uric acid degradation pathway in the fungal pathogen Cryptococcus neoformans. 2366 4

Uric acid stored in the fat body of cockroaches is a nitrogen reservoir mobilized in times of scarcity. The discovery of urease in Blattabacterium cuenoti, the primary endosymbiont of cockroaches, suggests that the endosymbiont may participate in cockroach nitrogen economy. However, bacterial urease may only be one piece in the entire nitrogen recycling process from insect uric acid. Thus, in addition to the uricolytic pathway to urea, there must be glutamine synthetase assimilating the released ammonia by the urease reaction to enable the stored nitrogen to be metabolically usable. None of the Blattabacterium genomes sequenced to date possess genes encoding for those enzymes. To test the host's contribution to the process, we have sequenced and analysed Blattella germanica transcriptomes from the fat body. We identified transcripts corresponding to all genes necessary for the synthesis of uric acid and its catabolism to urea, as well as for the synthesis of glutamine, asparagine, proline and glycine, i.e. the amino acids required by the endosymbiont. We also explored the changes in gene expression with different dietary protein levels. It appears that the ability to use uric acid as a nitrogen reservoir emerged in cockroaches after its age-old symbiotic association with bacteria.
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PMID:The cockroach Blattella germanica obtains nitrogen from uric acid through a metabolic pathway shared with its bacterial endosymbiont. 2507 97

Uric acid increased accumulation and/or reduced excretion in human bodies is closely related to pathogenesis of gout and hyperuricemia. It is highly affected by the high intake of food rich in purine. Uric acid is present in both higher plants and microorganisms with species dependent concentration. Urate-degrading enzymes are found both in plants and microorganisms but the mechanisms by which plant degrade uric acid was found to be different among them. Higher plants produce various metabolites which could inhibit xanthine oxidase and xanthine oxidoreductase, so prohibit the oxidation of hypoxanthine to xanthine then to uric acid in the purine metabolism. However, microorganisms produce group of degrading enzymes uricase, allantoinase, allantoicase and urease, which catalyze the degradation of uric acid to the ammonia. In humans, researchers found that several mutations caused a pseudogenization (silencing) of the uricase gene in ancestral apes which exist as an insoluble crystalloid in peroxisomes. This is in contrast to microorganisms in which uricases are soluble and exist either in cytoplasm or peroxisomes. Moreover, many recombinant uricases with higher activity than the wild type uricases could be induced successfully in many microorganisms. The present review deals with the occurrence of uric acid in plants and other organisms specially microorganisms in addition to the mechanisms by which plant extracts, metabolites and enzymes could reduce uric acid in blood. The genetic and genes encoding for uric acid in plants and microorganisms are also presented.
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PMID:Uric acid in plants and microorganisms: Biological applications and genetics - A review. 2874 14