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.

The Structure of 2-Oxo-4-hydroxy-4-carboxy-5-ureidoimidazoline Decarboxylase Provides Insights into the Mechanism of Uric Acid Degradation / Cendron, L; Berni, Rodolfo; Folli, Claudia; Ramazzina, Ileana; Percudani, Riccardo; Zanotti, G.. - In: THE JOURNAL OF BIOLOGICAL CHEMISTRY. - ISSN 0021-9258. - 282:(2007), pp. 18182-18189. [10.1074/jbc.M701297200]

The Structure of 2-Oxo-4-hydroxy-4-carboxy-5-ureidoimidazoline Decarboxylase Provides Insights into the Mechanism of Uric Acid Degradation.

BERNI, Rodolfo;FOLLI, Claudia;RAMAZZINA, Ileana;PERCUDANI, Riccardo;
2007-01-01

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.
2007
The Structure of 2-Oxo-4-hydroxy-4-carboxy-5-ureidoimidazoline Decarboxylase Provides Insights into the Mechanism of Uric Acid Degradation / Cendron, L; Berni, Rodolfo; Folli, Claudia; Ramazzina, Ileana; Percudani, Riccardo; Zanotti, G.. - In: THE JOURNAL OF BIOLOGICAL CHEMISTRY. - ISSN 0021-9258. - 282:(2007), pp. 18182-18189. [10.1074/jbc.M701297200]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11381/1642900
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