US EPA

1655637 

Journal Article 

Review 

Structure and function of xanthine oxidoreductase: where are we now? 

Harrison, R 

2002 

Yes 

Free Radical Biology and Medicine
ISSN: 0891-5849
EISSN: 1873-4596 

33 

6 

774-797 

English 

12208366 

10.1016/s0891-5849(02)00956-5 

WOS:000177940700007 

Xanthine oxidoreductase (XOR) is a complex molybdoflavoenzyme, present in milk and many other tissues, which has been studied for over 100 years. While it is generally recognized as a key enzyme in purine catabolism, its structural complexity and specialized tissue distribution suggest other functions that have never been fully identified. The publication, just over 20 years ago, of a hypothesis implicating XOR in ischemia-reperfusion injury focused research attention on the enzyme and its ability to generate reactive oxygen species (ROS). Since that time a great deal more information has been obtained concerning the tissue distribution, structure, and enzymology of XOR, particularly the human enzyme. XOR is subject to both pre- and post-translational control by a range of mechanisms in response to hormones, cytokines, and oxygen tension. Of special interest has been the finding that XOR can catalyze the reduction of nitrates and nitrites to nitric oxide (NO), acting as a source of both NO and peroxynitrite. The concept of a widely distributed and highly regulated enzyme capable of generating both ROS and NO is intriguing in both physiological and pathological contexts. The details of these recent findings, their pathophysiological implications, and the requirements for future research are addressed in this review. 

reactive oxygen species; nitric oxide; ischemia-reperfusion