1V97:
reference: The crystal structure of xanthine oxidoreductase during catalysis: implications for reaction mechanism and enzyme inhibition., Okamoto K, Matsumoto K, Hille R, Eger BT, Pai EF, Nishino T, Proc Natl Acad Sci U S A 2004 May 25;101(21):7931-6. Epub 2004 May 17. PMID: 15148401

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