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)

Bestatin, an aminopeptidase inhibitor, permits the degradation of cellular proteins to di- and tripeptides but interferes with the further breakdown of these peptides to amino acids. We propose to measure instant rates of protein degradation in skeletal muscles of intact mice by the accumulation of bestatin-induced intermediates. Muscle protein was labeled by injection of L-[guanidino-14C]arginine; 3 days later, maximum accumulation of intermediates was measured in abdominal wall muscles 10 min after the intravenous injection of 5 mg of bestatin. The peptides were partially purified and hydrolyzed in 6 N HCl, and the radioactivity in peptide-derived arginine was determined, after conversion to 14CO2 by treatment with arginase and urease. The measurement of bestatin-induced intermediates provides a unique tool for studying acute changes in muscle protein turnover in live mice. We observed a 62% increase in muscle protein breakdown after a 16-h fast, which was reversed by refeeding for 3.5 h, and a 38% increase after 3 days of protein depletion.
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PMID:Measurement of muscle protein degradation in live mice by accumulation of bestatin-induced peptides. 943 31

Incubation of mixed human saliva with arginine, ornithine, and proline for 30 min to 2 h at 40 degrees C leads to an appreciable consumption of the above amino acids. The rate of utilization is 0.2 to 0.5 ncat/ml of saliva. The rate of urea loss is higher by an order of magnitude: up to 11 ncat/ml. Putrescin, urea (after incubation with arginine), and ammonium are identified as the products of these reactions. The biological significance of such reactions is believed to consist in neutralization of carbohydrate fermentation products. The detected consumption of amino acids and urea indicates that mixed human saliva contains urease, arginase, ornithine decarboxylase, and, probably, proline reductase. Since the origin of these enzymes is probably bacterial, changes in their activity in the saliva can be regarded as an indicator of dysbacteriosis and a diagnostically important parameter.
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PMID:[The utilization of amino acids and urea by human oral fluid]. 947 2

Arginase (EC 3.5.3.1) transcript level and activity were measured in soybean (Glycine max L.) embryos from the reserve deposition stage to postgermination. Using a cDNA probe for a small soybean arginase gene family, no transcript was detected in developing embryos. However, arginase transcripts increased sharply on germination, reaching a maximum at 3 to 5 d after germination. There was low but measurable in vitro arginase specific activity in developing embryos (less than 6% of seedling maximum). During germination arginase specific activity increased in parallel with the sharply increasing arginase transcript level. Seedling arginase activity was largely localized in cotyledons. Arginase activity was assayed in vivo by measuring urea accumulation in a urease-deficient mutant. No urea was detected in developing embryos, whereas accumulated urea paralleled arginase specific activity and transcript level in germinating seedlings. As in planta embryos, cultured cotyledons did not accumulate urea when arginine (Arg) was provided with other amino acids in a "mock" seed-coat exudate. Arg as the sole nitrogen source was converted to urea but did not support cotyledon growth. There appeared to be a lack of recruitment of the low-level arginase activity to hydrolyze free Arg in developing embryos, thus avoiding a futile urea cycle.
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PMID:Arginase is inoperative in developing soybean embryos. 988 Mar 72

A secreted, glycosylated arginase (lectin) from Xanthoria parietina thallus binds to the cell wall of Xanthoria photobiont when cell wall urease has previously been induced. The uptake of this secreted arginase by the algal cell without cell wall ligand for the lectin increases the concentration of algal putrescine and it is followed by an apparent loss of chlorophyll. However, neither chlorophyllase activity has been detected nor chlorophyllide concentration increases after loading the cells with putrescine. The loss of chlorophyll can be explained by the loss of algal protoplast resulting from the action of a putrescine-activated glucanase and the split of their membrane in an hypoosmotic medium. The loss and split of protoplasts have been shown by light and transmission electron microscopy.
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PMID:Secreted, glycosylated arginase from Xanthoria parietina thallus induces loss of cytoplasmic material from Xanthoria photobionts. 992 41

Arginase of the Helicobacter pylori urea cycle hydrolyzes L-arginine to L-ornithine and urea. H. pylori urease hydrolyzes urea to carbon dioxide and ammonium, which neutralizes acid. Both enzymes are involved in H. pylori nitrogen metabolism. The roles of arginase in the physiology of H. pylori were investigated in vitro and in vivo, since arginase in H. pylori is metabolically upstream of urease and urease is known to be required for colonization of animal models by the bacterium. The H. pylori gene hp1399, which is orthologous to the Bacillus subtilis rocF gene encoding arginase, was cloned, and isogenic allelic exchange mutants of three H. pylori strains were made by using two different constructs: 236-2 and rocF::aphA3. In contrast to wild-type (WT) strains, all rocF mutants were devoid of arginase activity and had diminished serine dehydratase activity, an enzyme activity which generates ammonium. Compared with WT strain 26695 of H. pylori, the rocF::aphA3 mutant was approximately 1, 000-fold more sensitive to acid exposure. The acid sensitivity of the rocF::aphA3 mutant was not reversed by the addition of L-arginine, in contrast to the WT, and yielded a approximately 10, 000-fold difference in viability. Urease activity was similar in both strains and both survived acid exposure equally well when exogenous urea was added, indicating that rocF is not required for urease activity in vitro. Finally, H. pylori mouse-adapted strain SS1 and the 236-2 rocF isogenic mutant colonized mice equally well: 8 of 9 versus 9 of 11 mice, respectively. However, the rocF::aphA3 mutant of strain SS1 had moderately reduced colonization (4 of 10 mice). The geometric mean levels of H. pylori recovered from these mice (in log(10) CFU) were 6.1, 5.5, and 4.1, respectively. Thus, H. pylori rocF is required for arginase activity and is crucial for acid protection in vitro but is not essential for in vivo colonization of mice or for urease activity.
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PMID:Helicobacter pylori rocF is required for arginase activity and acid protection in vitro but is not essential for colonization of mice or for urease activity. 1057 36

The catabolism of arginine, an amino acid found in grape juice and wine, citrulline and ornithine was investigated in four lactic acid bacteria. Only Lactobacillus hilgardii X1B catabolized arginine and excreted citrulline into the medium. The recovery of arginine as ornithine was lower than the expected theoretical value. The arginase-urease pathway was not detected indicating that the amino acid degradation was carried out only by the arginine dihydrolase pathway. Oenococcus oeni m, a strain not able to utilize arginine, degraded citrulline that was completely recovered as ornithine, ammonia and CO2. Lactobacillus hilgardii X1B catabolized citrulline but it was only 44% recovered as ornithine. The citrulline utilization by Oenococcus oeni m may be important for two reasons: it can gain extra energy for growth from citrulline metabolism, and the amino-acid diminution could avoid the possibility of ethyl carbamate formation from the citrulline naturally present in wine.
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PMID:Arginine, citrulline and ornithine metabolism by lactic acid bacteria from wine. 1073 46

An enzymatic end-point method for the quantitative determination of L-arginine was evaluated with samples of synthetic wine and natural grape juice. The enzymes arginase, urease, and glutamate dehydrogenase were used in this simple assay, similar to those described for many metabolites by Boehringer-Mannheim. In synthetic wine, recovery of L-arginine ranged between 98.3 and 104.4% and the precision as coefficient of variation was between 0.4 and 1.47% in the concentration range of the method, 0-100 mg/L L-arginine. The recovery of L-arginine in a grape juice with added L-arginine after clarification with polyvinylpolypyrrolidone ranged between 100 and 101.3%, and the coefficient of variation was 0.6%. The method has low material costs of approximately 0.43 U.S.$ per assay, and the time course of the reaction facilitates measurement of several samples concurrently. The results of this evaluation indicate that the enzymatic assay is a preferred method over colorimetric methods for the manual determination of L-arginine.
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PMID:Quantitative determination of L-arginine by enzymatic end-point analysis. 1126 90

Aliphatic amidases (EC 3.5.1.4) are enzymes catalysing the hydrolysis of short-chain amides to produce ammonia and the corresponding organic acid. Such an amidase, AmiE, has been detected previously in Helicobacter pylori. Analysis of the complete H. pylori genome sequence revealed the existence of a duplicated amidase gene that we named amiF. The corresponding AmiF protein is 34% identical to its AmiE paralogue. Because gene duplication is widely considered to be a fundamental process in the acquisition of novel enzymatic functions, we decided to study and compare the functions of the paralogous amidases of H. pylori. AmiE and AmiF proteins were overproduced in Escherichia coli and purified by a two-step chromatographic procedure. The two H. pylori amidases could be distinguished by different biochemical characteristics such as optimum pH or temperature. AmiE hydrolysed propionamide, acetamide and acrylamide and had no activity with formamide. AmiF presented an unexpected substrate specificity: it only hydrolysed formamide. AmiF is thus the first formamidase (EC 3.5.1.49) related to aliphatic amidases to be described. Cys-165 in AmiE and Cys-166 in AmiF were identified as residues essential for catalysis of the corresponding enzymes. H. pylori strains carrying single and double mutations of amiE and amiF were constructed. The substrate specificities of these enzymes were confirmed in H. pylori. Production of AmiE and AmiF proteins is dependent on the activity of other enzymes involved in the nitrogen metabolism of H. pylori (urease and arginase respectively). Our results strongly suggest that (i) the H. pylori paralogous amidases have evolved to achieve enzymatic specialization after ancestral gene duplication; and (ii) the production of these enzymes is regulated to maintain intracellular nitrogen balance in H. pylori.
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PMID:The AmiE aliphatic amidase and AmiF formamidase of Helicobacter pylori: natural evolution of two enzyme paralogues. 1135 66

The mobilization and utilization of the major storage proteins in loblolly pine (Pinus taeda L.) seeds following imbibition were investigated. Most of the seed protein reserves were contained within the megagametophyte. Breakdown of these proteins occurred primarily following radicle emergence and correlated with a substantial increase in the free amino acid pool in the seedling; the majority of this increase appeared to be the result of export from the megagametophyte. The megagametophyte was able to break down storage proteins and export free amino acids in the absence of the seedling. Arginine (Arg) was the most abundant amino acid among the principal storage proteins of the megagametophyte and was a major component of the free amino acid pools in both the seedling and the megagametophyte. The increase in free Arg coincided with a marked increase in arginase activity, mainly localized within the cotyledons and epicotyl of the seedling. Arginase activity was negligible in isolated seedlings. Experiments with phenylphosphorodiamidate, a urease inhibitor, supported the hypothesis that arginase participates in Arg metabolism in the seedling. The results of this study indicate that Arg could play an important role in the nutrition of loblolly pine during early seedling growth.
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PMID:Amino Acid Utilization in Seeds of Loblolly Pine during Germination and Early Seedling Growth (I. Arginine and Arginase Activity). 1222 64

Ammonia production is of great importance for the gastric pathogen Helicobacter pylori as a nitrogen source, as a compound protecting against gastric acidity, and as a cytotoxic molecule. In addition to urease, H. pylori possesses two aliphatic amidases responsible for ammonia production: AmiE, a classical amidase, and AmiF, a new type of formamidase. Both enzymes are part of a regulatory network consisting of nitrogen metabolism enzymes, including urease and arginase. We examined the role of the H. pylori amidases in vivo by testing the gastric colonization of mice with H. pylori SS1 strains carrying mutations in amiE and/or amiF and in coinfection experiments with wild-type and double mutant strains. A new cassette conferring resistance to gentamicin was used in addition to the kanamycin cassette to construct the double mutation in strain SS1. Our data indicate that the amidases are not essential for colonization of mice. The search for amiE and amiF genes in 53 H. pylori strains from different geographic origins indicated the presence of both genes in all these genomes. We tested for the presence of the amiE and amiF genes and for amidase and formamidase activities in eleven Helicobacter species. Among the gastric species, H. acinonychis possessed both amiE and amiF, H. felis carried only amiF, and H. mustelae was devoid of amidases. H. muridarum, which can colonize both mouse intestine and stomach, was the only enterohepatic species to contain amiE. Phylogenetic trees based upon the sequences of H. pylori amiE and amiF genes and their respective homologs from other organisms as well as the amidase gene distribution among Helicobacter species are strongly suggestive of amidase acquisition by horizontal gene transfer. Since amidases are found only in Helicobacter species able to colonize the stomach, their acquisition might be related to selective pressure in this particular gastric environment.
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PMID:Presence of active aliphatic amidases in Helicobacter species able to colonize the stomach. 1450 Apr 81


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