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X‐ray, ESR, and quantum mechanics studies unravel a spin well in the cofactor‐less urate oxidase
Author(s) -
Gabison Laure,
Chopard Claude,
Colloc'h Nathalie,
Peyrot Fabienne,
Castro Bertrand,
Hajji Mohamed El,
Altarsha Muhannad,
Monard Gerald,
Chiadmi Mohamed,
Prangé Thierry
Publication year - 2011
Publication title -
proteins: structure, function, and bioinformatics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.699
H-Index - 191
eISSN - 1097-0134
pISSN - 0887-3585
DOI - 10.1002/prot.23022
Subject(s) - chemistry , electron paramagnetic resonance , photochemistry , urate oxidase , molecule , substrate (aquarium) , hydrogen peroxide , spin states , crystallography , enzyme , inorganic chemistry , nuclear magnetic resonance , organic chemistry , physics , oceanography , geology
Urate oxidase (EC 1.7.3.3 or UOX) catalyzes the conversion of uric acid using gaseous molecular oxygen to 5‐hydroxyisourate and hydrogen peroxide in absence of any cofactor or transition metal. The catalytic mechanism was investigated using X‐ray diffraction, electron spin resonance spectroscopy (ESR), and quantum mechanics calculations. The X‐ray structure of the anaerobic enzyme–substrate complex gives credit to substrate activation before the dioxygen fixation in the peroxo hole, where incoming and outgoing reagents (dioxygen, water, and hydrogen peroxide molecules) are handled. ESR spectroscopy establishes the initial monoelectron activation of the substrate without the participation of dioxygen. In addition, both X‐ray structure and quantum mechanic calculations promote a conserved base oxidative system as the main structural features in UOX that protonates/deprotonates and activate the substrate into the doublet state now able to satisfy the Wigner's spin selection rule for reaction with molecular oxygen in its triplet ground state. Proteins 2011; © 2011 Wiley‐Liss, Inc.