Structure of OHCU decarboxylase in complex with guanine

Experimental Data Snapshot

  • Resolution: 1.80 Å
  • R-Value Free: 0.257 
  • R-Value Work: 0.221 
  • R-Value Observed: 0.223 

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The 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

  • 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.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
OHCU decarboxylase
A, B, C, D, E
A, B, C, D, E, F
174Danio rerioMutation(s): 0 
Gene Names: zgc:158663
Find proteins for A1L259 (Danio rerio)
Explore A1L259 
Go to UniProtKB:  A1L259
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupA1L259
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 1.80 Å
  • R-Value Free: 0.257 
  • R-Value Work: 0.221 
  • R-Value Observed: 0.223 
  • Space Group: P 32
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 102.223α = 90
b = 102.223β = 90
c = 103.892γ = 120
Software Package:
Software NamePurpose
ADSCdata collection
MOSFLMdata reduction
CCP4data scaling

Structure Validation

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Ligand Structure Quality Assessment 

Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2007-04-10
    Type: Initial release
  • Version 1.1: 2008-05-01
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2014-04-02
    Changes: Database references
  • Version 1.4: 2023-10-25
    Changes: Data collection, Database references, Derived calculations, Refinement description