Download MendeleyThe structure of 2-oxo-4-hydroxy-4-carboxy-5-ureidoimidazoline decarboxylase provides insights into the mechanism of uric acid degradation.
Cendron, L., Berni, R., Folli, C., Ramazzina, I., Percudani, R., Zanotti, G.(2007) J Biol Chem 282: 18182-18189
- PubMed: 17428786
- DOI: https://doi.org/10.1074/jbc.M701297200
- Primary Citation of Related Structures:
2O70, 2O73, 2O74 - PubMed Abstract:
The complete degradation of uric acid to (S)-allantoin, as recently elucidated, involves three enzymatic reactions. Inactivation by pseudogenization of the genes of the pathway occurred during hominoid evolution, resulting in a high concentration of urate in the blood and susceptibility to gout. Here, we describe the 1.8A resolution crystal structure of the homodimeric 2-oxo-4-hydroxy-4-carboxy-5-ureidoimidazoline decarboxylase, which catalyzes the last step in the urate degradation pathway, for both ligand-free enzyme and enzyme in complex with the substrate analogs (R)-allantoin and guanine. Each monomer comprises ten alpha-helices, grouped into two domains and assembled in a novel fold. The structure and the mutational analysis of the active site have allowed us to identify some residues that are essential for catalysis, among which His-67 and Glu-87 appear to play a particularly significant role. Glu-87 may facilitate the exit of the carboxylate group because of electrostatic repulsion that destabilizes the ground state of the substrate, whereas His-67 is likely to be involved in a protonation step leading to the stereoselective formation of the (S)-allantoin enantiomer as reaction product. The structural and functional characterization of 2-oxo-4-hydroxy-4-carboxy-5-ureidoimidazoline decarboxylase can provide useful information in view of the potential use of this enzyme in the enzymatic therapy of gout.
Organizational Affiliation:
Department of Chemistry, University of Padua, and Instituto di Chimica Biomolecolare-Consiglio Nazionale delle Ricerche, Section of Padua, Via Marzolo 1, 35131 Padua, Italy; Venetian Institute of Molecular Medicine, Via Orus 2, 35127 Padua, Italy.
