Direct evidence for a peroxide intermediate and a reactive enzyme-substrate-dioxygen configuration in a cofactor-free oxidase

Soi Bui, David Von Stetten, Pablo G. Jambrina, Thierry Prangé, Nathalie Colloc'H, Daniele De Sanctis, Antoine Royant, Edina Rosta, Roberto A. Steiner*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

45 Citations (Scopus)

Abstract

Cofactor-free oxidases and oxygenases promote and control the reactivity of O2 with limited chemical tools at their disposal. Their mechanism of action is not completely understood and structural information is not available for any of the reaction intermediates. Near-atomic resolution crystallography supported by in crystallo Raman spectroscopy and QM/MM calculations showed unambiguously that the archetypical cofactor-free uricase catalyzes uric acid degradation via a C5(S)-(hydro)peroxide intermediate. Low X-ray doses break specifically the intermediate C5-OO(H) bond at 100 K, thus releasing O2 in situ, which is trapped above the substrate radical. The dose-dependent rate of bond rupture followed by combined crystallographic and Raman analysis indicates that ionizing radiation kick-starts both peroxide decomposition and its regeneration. Peroxidation can be explained by a mechanism in which the substrate radical recombines with superoxide transiently produced in the active site.

Original languageEnglish
Pages (from-to)13710-13714
Number of pages5
JournalANGEWANDTE CHEMIE-INTERNATIONAL EDITION
Volume53
Issue number50
DOIs
Publication statusPublished - 8 Dec 2014

Keywords

  • Dioxygen
  • Enzymatic mechanisms
  • Oxidases
  • Reaction intermediates
  • Structural enzymology

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