Gabison Laure, Chiadmi Mohamed, Colloc'h Nathalie, Castro Bertrand, El Hajji Mohamed, Prangé Thierry
Laboratoire de cristallographie et RMN biologiques (UMR 8015 CNRS), Faculté de Pharmacie, Université Paris V, 4 avenue de l'Observatoire, 75270 Paris Cedex 06, France.
FEBS Lett. 2006 Apr 3;580(8):2087-91. doi: 10.1016/j.febslet.2006.03.007. Epub 2006 Mar 10.
Urate oxidase from Aspergillus flavus catalyzes the degradation of uric acid to [S]-allantoin through 5-hydroxyisourate as a metastable intermediate. The second degradation step is thought either catalyzed by another specific enzyme, or spontaneous. The structure of the enzyme was known at high resolution by X-ray diffraction of I222 crystals complexed with a purine-type inhibitor (8-azaxanthin). Analyzing the X-ray structure of urate oxidase treated with an excess of urate, the natural substrate, shows unexpectedly that the active site recaptures [S]-allantoin from the racemic end product of a second degradation step.
来自黄曲霉的尿酸氧化酶通过5-羟基异尿酸作为亚稳态中间体催化尿酸降解为[S]-尿囊素。第二个降解步骤被认为要么由另一种特定酶催化，要么是自发进行的。通过与嘌呤型抑制剂（8-氮杂黄嘌呤）复合的I222晶体的X射线衍射，该酶的结构在高分辨率下是已知的。用过量的天然底物尿酸处理尿酸氧化酶的X射线结构分析意外地表明，活性位点从第二个降解步骤的外消旋终产物中重新捕获了[S]-尿囊素。
