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)

Seven Bacillus strains including one of the original Bacillus fastidiosus strains of Den Dooren de Jong could grow on urate, allantoin, and, except one, on allantoate. No growth could be detected on adenine, guanine, hypoxanthine, xanthine, and on degradation products of allantoate. Some strains grew very slowly in complex media. The metabolic pathway from urate to glyoxylate involved uricase, S(+)-allantoinase, allantoate amidohydrolase, S(-)-ureidoglycolase, and, in some strains, urease.
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PMID:Uric acid degradation by Bacillus fastidiosus strains. 124 68

The wild-type strain of Neurospora crassa Em 5297a can utilize allantoin as a sole nitrogen source. The pathway of allantoin utilization is via its conversion into allantoic acid and urea, followed by the breakdown of urea to ammonia. This is shown by the inability of the urease-less mutant, N. crassa 1229, to grow on allantoin as a sole nitrogen source and by the formation of allantoate and urea by pre-formed mycelia of this mutant. In the wild strain (Em 5297a) thiourea is tenfold more toxic on an allantoin medium than on an inorganic nitrogen medium; allantoin as well as urea counteract thiourea toxicity in the allantoin nitrogen medium. This selective toxicity of thiourea for the mould utilizing allantoin nitrogen does not, however, result in an impairment of allantoin uptake, allantoinase activity or the formation of urea from allantoin. The only process affected by thiourea is the synthesis of urease; urea antagonizes this effect of thiourea in N. crassa.
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PMID:The effect of thiourea on ureide metabolism in Neurospora crassa. 427 57

Saccharomyces cerevisiae can degrade allantoin in five steps to glyoxylate, ammonia, and "CO(2)." We previously demonstrated that synthesis of the urea carboxylase-allophanate hydrolase multienzyme complex is contingent upon the presence of allophanic acid, the product of the urea carboxylase reaction. Since these enzymes catalyze the last two reactions of allantoin degradation, experiments were performed to establish whether or not the presence of allophanic acid was required for synthesis of any other enzymes participating in this degradative pathway. The data presented here indicate that allophanic acid is required for synthesis of all enzymes participating in allantoin degradation. This conclusion is based upon the observation that: (i) wild-type strains produced a large amount of allantoinase upon addition of allantoin, allantoate, ureidoglycolate, or urea to the medium, (ii) no increase in activity was observed unless the added compound could be metabolized to allophanate, (iii) strains lacking allophanate hydrolase contained large amounts of allantoinase even in the absence of added urea, and (iv) the urea analogue, formamide, was capable of inducing allantoinase synthesis in wild-type strains but would not serve this function in a strain lacking urea carboxylase.
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PMID:Induction of the allantoin degradative enzymes in Saccharomyces cerevisiae by the last intermediate of the pathway. 459 22

Allantoinase hydrolyzes allantoin, a purine metabolite and a nitrogen transport molecule in plants, to form allantoic acid. The standard enzyme assay involves acid-catalyzed product decomposition to form urea and glyoxylate, reaction of glyoxylate with phenylhydrazine, and oxidative conversion of phenylhydrazone to 1, 5-diphenylformazan that is measured colorimetrically. When used with crude cell extracts this assay is problematic and its complexity is a hindrance to detailed enzyme characterization; thus, three alternative assays were developed. In the first assay, 2, 4-dinitrophenylhydrazine was reacted with allantoate-derived glyoxylate and the concentration of hydrazone was measured directly by its absorbance at 450 nm. This assay exhibited enhanced reproducibility compared to the standard method and entailed fewer steps, but was 3-fold less sensitive. The second assay combined allantoate decomposition and glyoxylate reaction with o-phenylenediamine to yield a quinoxalone that was detected by its absorbance at 340 nm. This one-step method was the least error prone of those examined, but was more than 10-fold less sensitive than the standard assay. The third assay involved urease-catalyzed hydrolysis of allantoate-derived urea, followed by reaction of the released ammonia to form indophenol. This was the most laborious of the assays, but was more sensitive than the standard method.
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PMID:Assays for allantoinase. 1003 61

The hypothesis that soybean (Glycine max L. [Merrill]) catabolizes ureides to urea to a physiologically significant extent was tested and rejected. Urease-negative (eu3-e1/eu3-e1) plants were supported by fixed N2 or by 2 mM NH4NO3, so that xylem-borne nitrogen contained predominantly ureides (allantoin and allantoic acid) or amide amino acids, respectively. Seed nitrogen yield was equal on either nitrogen regime, although 35-d-old fixing plants accumulated about 6 times more leaf urea. In callus, lack of an active urease reduced growth on either arginine or allantoin as the sole nitrogen source, but the reduction was greater on arginine (73%) than on allantoin (39%). Furthermore, urease-negative cells accumulated 17 times more urea than urease-positive cells on arginine; for allantoin the ratio was 1.8. Urease-negative callus accumulated urea at 3% the rate of seedlings. To test whether urea accumulating in urease-negative seedlings was derived from ureides, seeds were first allowed to imbibe in 1 mM allopurinol, an inhibitor of ureide formation. Seedling ureides were decreased by 90%, but urea levels were unchanged. Thus, ureides are poor precursors of urea, which was confirmed in seedlings that converted no more than 5% of seed-absorbed [14C-ureido]allantoate to [14C]urea, whereas 40 to 70% of [14C-guanido]arginine was recovered as [14C]urea.
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PMID:Urease Is Not Essential for Ureide Degradation in Soybean. 1222 87

Agaricus bisporus is able to use urate, allantoin, allantoate, urea and alloxanate as nitrogen sources for growth. The presence of urate oxidase, allantoinase, ureidoglycolase and urease activities, both in fruit bodies and mycelia, points to a degradative pathway for urate similar to that found in various microorganisms. So far all efforts to demonstrate the enzyme responsible for allantoate degradation failed. A urease inhibitor appeared to be present in cell-free extracts from fruit bodies.
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PMID:Purine degradation in the edible mushroom Agaricus bisporus. 1263 Mar 18

The ability of two soybean (Glycine max L. [Merrill]) cultivars, 'Williams 82' and 'Maple Arrow', which were reported to use different ureide degradation pathways, to degrade the ureides allantoin and allantoate was investigated. Protein fractions and total leaf homogenates from the fourth trifoliate leaves of both cultivars were examined for the ability to evolve either (14)CO(2) or [(14)C]urea from (14)C-labelled ureides in the presence of various inhibitors. (14)CO(2) evolution from [2,7-(14)C]allantoate was catalysed by 25-50% saturated ammonium sulphate fractions of both cultivars. This activity was inhibited by acetohydroxamate (AHA), which has been used to inhibit plant ureases, but not by phenylphosphorodiamidate (PPD), a more specific urease inhibitor. Thus, in both cultivars, allantoate may be metabolized by allantoate amidohydrolase. This activity was sensitive to EDTA, consistent with previous reports demonstrating that allantoate amidohydrolase requires manganese for full activity. Total leaf homogenates of both cultivars evolved both (14)CO(2) and [(14)C]urea from [2,7-(14)C] (ureido carbon labelled) allantoin, not previously reported in either 'Williams 82' or in 'Maple Arrow'. In situ leaf degradation of (14)C-labelled allantoin confirmed that both urea and CO(2)/NH(3) are direct products of ureide degradation. Growth of plants in the presence of PPD under fixing and non-fixing conditions caused urea accumulation in both cultivars, but did not have a significant impact on total seed nitrogen. Urea levels were higher in N-fixing plants of both cultivars. Contrary to previous reports, no significant biochemical difference was found in the ability of these two cultivars to degrade ureides under the conditions used.
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PMID:Soybean cultivars 'Williams 82' and 'Maple Arrow' produce both urea and ammonia during ureide degradation. 1502 Jun 40

Allantoate degradation was demonstrated in the extracts of ungerminated seeds and roots, stems and leaves in germinated seedlings of French bean (Phaseolus vulgaris L.). Activity of allantoate-degrading enzyme could only be measured when phenylhydrazine was included in the assay mixture. Partial purification of allantoate-degrading enzyme from seedlings was performed and two fractions with allantoate-degrading enzyme activity were obtained. The molecular mass of the first fraction was over 200 kD and that of the second one was 13.5 kD. The allantoate-degrading enzyme with small molecular weight contained no activity of either ureidoglycolate-degrading enzyme or urease. From the stoichiometry of the reaction catalyzed by the allantoate-degrading enzyme with small molecular weight it followed that the enzyme was allantoate amidohydrolase (EC 3.5.3.9). The optimal pH for the allantoate amidohydrolase was 8.5. Mn(2+) ions were essential for enzymatic activity. Glyoxylate and glycolate strongly inhibited the enzyme activity. The lysine and tryptophan residues were essential to the enzymatic catalysis; thiol group and tyrosyl residues were not involved in the enzyme catalysis.
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PMID:Some properties of the allantoate amidohydrolase from French bean seedlings. 1562 97

In leaf pieces from nodulated soybean (Glycine max [L] Merr cv Maple Arrow) plants, [(14)C]urea-dependent NH(3) and (14)CO(2) production in the dark showed an approximately 2:1 stoichiometry and was decreased to less than 11% of the control (12-19 micromoles NH(3) per gram fresh weight per hour) in the presence of 50 millimolar acetohydroxamate, a urease inhibitor. NH(3) and CO(2) production from the utilization of [2-(14)C] allantoin also exhibited a 2:1 stoichiometry and was reduced to a similar extent by the presence of acetohydroxamate with a concomitant accumulation of urea which entirely accounted for the loss in NH(3) production. The almost complete sensitivity of NH(3) and CO(2) production from allantoin and urea metabolism to acetohydroxamate, together with the observed stoichiometry, indicated a path of ureide assimilation (2.0 micromoles per gram leaf fresh weight per hour) via allantoate, ureidoglycolate, and glyoxylate with the production of two urea molecules yielding, in turn, four molecules of NH(3) and two molecules of CO(2).
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PMID:Ureide metabolism in leaves of nitrogen-fixing soybean plants. 1666 33

A Mn(2+)-dependent enzymic breakdown of allantoate has been detected in crude and partially purified extracts of developing soybeans. The products detected were CO(2), NH(3), glyoxylate, labile glyoxylate derivatives, and low levels of urea. Urea is initially produced at less than 10% the rate of urease-independent CO(2) release indicating that the activity is not allantoate amidinohydrolase (i.e. urea is not directly cleaved off allantoate). The urease-independent CO(2) releasing activity has an apparent K(m) of 1.0 millimolar for allantoate. Ethylenediaminetetraacetate, borate, and acetohydroxamate (all at 10 millimolar) inhibit the enzymic production of NH(3), CO(2), and labile glyoxylate derivatives from allantoate. However, the potent urease inhibitor, phenyl phosphordiamidate does not inhibit CO(2) and NH(3) release indicating that the action of acetohydroxamate is not due to its inhibition of urease. That the allantoatedegrading activity was more than 5-fold greater in seed coats than in embryos is consistent with the data of Rainbird et al. (Plant Physiol 1984 74: 329-334) which indicate that available ureides are metabolized before reaching the embryo. 2-Ethanolthio, 2'ureido, acetic acid (NH(2)COHNCHCO(2)HSCH(2)CH(2)OH), the first allantoate-derived product detected by HPLC analysis, is an addition produced of mercaptoethanol with an unidentified enzymically produced ureido intermediate that is not derived from ureidoglycolate or oxalurate.
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PMID:Enzymic degradation of allantoate in developing soybeans. 1666 92


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