Inactivation of urate oxidase by a system composed of lactoperoxidase, hydrogen peroxide and bromide

✍ Scribed by Takeshi Odajima; Mihoko Onishi

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 171 KB
• Volume: 16
• Category: Article
• ISSN: 0263-6484
• DOI: 10.1002/(sici)1099-0844(199806)16:2<139::aid-cbf781>3.0.co;2-2

✦ Synopsis

Urate oxidase from Candida utilis, an enzyme containing an essential thiol, was examined for its sensitivity to lactoperoxidase, an oxidant present in breast milk. Upon exposure to a system composed of lactoperoxidase, hydrogen peroxide and bromide at moderately alkaline pH, the urate oxidase exhibited comparable activity to the untreated enzyme; but upon exposure at moderately acidic pH, it lost its activity completely. Thus the lactoperoxidase-H2O2-bromide system significantly inactivated urate oxidase only at moderately acidic pH. This inactivation was prevented by the presence of N-acetylmethionine, a methionine analogue, or glutathione, which is a thiol compound analogous to an amino acid, indicating that it was probably due to the oxidation and damage of the methionine residue and/or the thiol group in the urate oxidase by the lactoperoxidase system, that loss of catalytic activity of the urate oxidase occurred.