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)

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

We demonstrate that allantoate is catabolized in soybean seedcoat extracts by an enzyme complex that has allantoate amidohydrolase and ureidoglycolate amidohydrolase activities. Soybean seedcoat extracts released (14)CO(2) from [ureido-(14)C]ureidoglycolate under conditions in which urease is not detectable. CO(2) and glyoxylate are enzymically released in a one to one ratio indicating that ureidoglycolate amidohydrolase is the responsible activity. Ureidoglycolate amidohydrolase has a K(m) of 85 micromolar for ureidoglycolate. Glyoxylate and CO(2) are enzymically released from allantoate at linear rates in a one to 2.3 ratio from 5 to 30 min. This ratio is consistent with the degradation of allantoate to two CO(2) and one glyoxylate with approximately 23% of the allantoate degraded reacting with 2-mercaptoethanol to yield 2-hydroxyethylthio, 2'-ureido, acetate (RG Winkler, JC Polacco, DG Blevins, DD Randall 1985 Plant Physiol 79: 787-793). That [(14)C]urea production from [2,7-(14)C]allantoate is not detectable indicates that allantoate-dependent glyoxylate production is enzymic and not a result of nonenzymic hydrolysis of a ureido intermediate (nonenzymic hydrolysis releases urea). These results and those from intact tissue studies (RG Winkler DG Blevins, JC Polacco, DD Randall 1987 Plant Physiol 83: 585-591) suggest that soybeans have a second amidohydrolase reaction (ureidoglycolate amidohydrolase) that follows allantoate amidohydrolase in allantoate catabolism. The rate of (14)CO(2) release from [2,7-(14)C]allantoate is not reduced when the volume of the reaction mixture is increased, suggesting that the release of (14)CO(2) is not dependent on the accumulation of free intermediates. That [2,7-(14)C]allantoate dependent (14)CO(2) release is not proportionally diluted by unlabeled ureidoglycolate indicates that the reaction is carried out by an enzyme complex. This is the first report of ureidoglycolate amidohydrolase activity in any organism and the first in vitro demonstration in plants that the ureido-carbons of allantoate can be completely degraded to CO(2) without a urea intermediate.
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PMID:Ureide Catabolism in Soybeans : III. Ureidoglycolate Amidohydrolase and Allantoate Amidohydrolase Are Activities of an Allantoate Degrading Enzyme Complex. 1666 35