An alternative pathway for ureide usage in legumes: enzymatic formation of a ureidoglycolate adduct in Cicer arietinum and Phaseolus vulgaris.
Ureidoglycolate is an intermediate in the degradation of the ureides, allantoin and allantoate, found in many organisms. In some leguminous plant species these compounds are used to transport recently fixed nitrogen in the root nodules to the aerial parts of the plant. In the present study, it was demonstrated that purified ureidoglycolases from chickpea (Cicer arietinum) and French bean (Phaseolus vulgaris) do not produce glyoxylate, and can use phenylhydrazine as a substrate with K(m) values of 4.0 mM and 8.5 mM, respectively. Furthermore, these enzymes catalyse the transfer of the ureidoglycolyl group to phenylhydrazine to produce ureidoglycolyl phenylhydrazide, which degrades non-enzymatically to glyoxylate phenylhydrazone and urea. This supports their former classification as ureidoglycolate urea-lyases. The enzymatic reaction catalysed by the characterized ureidoglycolases uncovered here can be viewed as a novel type of phenylhydrazine ureidoglycolyl transferase. The implications of these findings for ureide metabolism in legume nitrogen metabolism are discussed.
Muñoz
Alfonso
A
Departamento de Genética Molecular de Plantas, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas (CSIC), E-28049 Madrid, Spain.
Bannenberg
Gerard L
GL
Montero
Olimpio
O
Cabello-Díaz
Juan Miguel
JM
Piedras
Pedro
P
Pineda
Manuel
M
D019760:Amidine-Lyases / Q000235:genetics / Q000378:metabolism*; D029863:Cicer / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D006016:Glycolates / Q000378:metabolism*; D053858:Metabolic Networks and Pathways; D009584:Nitrogen / Q000378:metabolism; D027805:Phaseolus / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D014508:Urea / Q000378:metabolism*
D006016:Glycolates; D010940:Plant Proteins; C031149:glycolic acid; D014508:Urea; D019760:Amidine-Lyases; C033757:ureidoglycollate lyase; D009584:Nitrogen