Document Detail


Ureide Catabolism in Soybeans : III. Ureidoglycolate Amidohydrolase and Allantoate Amidohydrolase Are Activities of an Allantoate Degrading Enzyme Complex.
MedLine Citation:
PMID:  16666035     Owner:  NLM     Status:  PubMed-not-MEDLINE    
Abstract/OtherAbstract:
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.
Authors:
R G Winkler; D G Blevins; D D Randall
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Plant physiology     Volume:  86     ISSN:  0032-0889     ISO Abbreviation:  Plant Physiol.     Publication Date:  1988 Apr 
Date Detail:
Created Date:  2010-06-29     Completed Date:  2010-07-02     Revised Date:  2010-09-14    
Medline Journal Info:
Nlm Unique ID:  0401224     Medline TA:  Plant Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1084-8     Citation Subset:  -    
Affiliation:
Interdisciplinary Plant Biochemistry and Physiology Group, Curtis Hall, University of Missouri, Columbia, Missouri 65211.
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