Analytical Sciences

Electrochemistry of Xanthine Oxidase and Its Interaction with Nitric Oxide

Hui ZHOU,* Yi XU,* Ting CHEN,* Iwao SUZUKI,** and Genxi LI*

*Department of Biochemistry and National Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing 210093, P. R. China
**Graduate School of Pharmaceutical Sciences, Tohoku University, Aramaki, Aoba, Sendai 980-8578, Japan

With the help of nanocrystalline TiO₂, the direct electrochemistry of xanthine oxidase (XOD) was achieved and two pairs of redox waves were observed. The interaction between XOD and nitric oxide (NO) was also investigated. The experimental results reveal that NO can be reduced at a XOD-nano TiO₂ film modified electrode. When the NO concentration was low, the reduced product, HNO, would inactivate the protein. However, when the NO concentration was high, HNO would continue to react with NO to form N₂O₂- and N₃O₃-, which would not inhibit XOD, and thus the amount of active protein did not decrease any further.

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