The role of xanthine dioxygenase in the biosynthetic pathway of 2-aza-8-oxohypoxanthine of Lepista sordida.

2-Azahypoxanthine (AHX) and 2-aza-8-oxohypoxanthine (AOH), discovered as causal substances of fairy rings are known to be endogenous in the fairy ring-forming Lepista sordida. In this study, we showed that xanthine dioxygenase, an a-ketoglutarate-dependent dioxygenase, might catalyze the conversion of AHX to AOH in the fungus. Furthermore, this enzyme is the first reported molybdopterin-independent protein of hypoxanthine metabolism.