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Identification and purification of hydroxyisourate hydrolase, a novel ureide-metabolizing enzyme

We report the identification and purification of a novel enzyme from soybean root nodules that catalyzes the hydrolysis of 5-hydroxyisourate, which is the true product of the urate oxidase reaction. The product of this reaction is 2-oxo-4-hydroxy-4-carboxy-5-ureidoimidazoline, and the new enzyme is...

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Bibliographic Details
Published in:The Journal of biological chemistry 1999-11, Vol.274 (48), p.33863-33865
Main Authors: Sarma, A.D, Serfozo, P, Kahn, K, Tipton, P.A
Format: Article
Language:English
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Summary:We report the identification and purification of a novel enzyme from soybean root nodules that catalyzes the hydrolysis of 5-hydroxyisourate, which is the true product of the urate oxidase reaction. The product of this reaction is 2-oxo-4-hydroxy-4-carboxy-5-ureidoimidazoline, and the new enzyme is designated 5-hydroxyisourate hydrolase. The enzyme was purified from crude extracts of soybean root nodules ∼100-fold to apparent homogeneity with a final specific activity of 10 μmol/min/mg. The enzyme exhibited a native molecular mass of ∼68 kDa by gel filtration chromatography and migrated as a single band on SDS-polyacrylamide gel electrophoresis with a subunit molecular mass of 68 ± 2 kDa. The purified enzyme obeyed normal Michaelis-Menten kinetics, and the K m for 5-hydroxyisourate was determined to be 15 μ m . The amino-terminal end of the purified protein was sequenced, and the resulting sequence was not found in any available data bases, confirming the novelty of the protein. These data suggest the existence of a hitherto unrecognized enzymatic pathway for the formation of allantoin.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.274.48.33863