Bovine xanthine oxidase electrocatalysis: substrate oxidation and its role in nitrite reduction

IF 2.8 3区化学 Q3 BIOCHEMISTRY & MOLECULAR BIOLOGY

Journal of Biological Inorganic Chemistry Pub Date : 2026-04-27 DOI:10.1007/s00775-026-02146-z

Peter D. Giang, Dimitri Niks, Russ Hille, Paul V. Bernhardt

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Abstract

Xanthine oxidase plays a central role in purine catabolism in animals, plants and bacteria where it oxidises hypoxanthine to xanthine and xanthine to uric acid. In this work we have immobilised bovine xanthine oxidase on a glassy carbon electrode within a glutaraldehyde film and demonstrated hypoxanthine and xanthine oxidase electrocatalysis using mediator methylene blue as a mediator. The role of xanthine oxidase in the reduction of nitrite to nitric oxide has been probed in two ways. Using the electrochemically reduced mediator methyl viologen, nitrite reduction by xanthine oxidase is complicated by non-enzymatic reduction of nitrite by the mediator. Using hypoxanthine as reductant, nitrite reduction occurs but the product nitric oxide rapidly inactivates the enzyme. Xanthine oxidase can be restored to its functional form by redox cycling on an electrode in the presence of sulfide showing that nitric oxide leads to desulfuration of the molybdenum active site.

Graphical abstract

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牛黄嘌呤氧化酶电催化：底物氧化及其在亚硝酸盐还原中的作用。

黄嘌呤氧化酶在动物、植物和细菌的嘌呤分解代谢中起着核心作用，它将次黄嘌呤氧化为黄嘌呤，将黄嘌呤氧化为尿酸。在这项工作中，我们将牛黄嘌呤氧化酶固定在戊二醛膜内的玻碳电极上，并使用介质亚甲基蓝作为介质演示了次黄嘌呤和黄嘌呤氧化酶的电催化作用。黄嘌呤氧化酶在亚硝酸盐还原为一氧化氮中的作用已经从两方面进行了探讨。采用电化学还原介质紫紫甲基，黄嘌呤氧化酶对亚硝酸盐的还原与介质对亚硝酸盐的非酶还原是复杂的。使用次黄嘌呤作为还原剂，发生亚硝酸盐还原，但产物一氧化氮迅速使酶失活。黄嘌呤氧化酶可以通过在硫化物存在的电极上的氧化还原循环恢复到其功能形式，这表明一氧化氮导致钼活性位点的脱硫。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Journal of Biological Inorganic Chemistry 化学-生化与分子生物学

CiteScore

5.90

自引率

3.30%

发文量

审稿时长

3 months

期刊介绍： Biological inorganic chemistry is a growing field of science that embraces the principles of biology and inorganic chemistry and impacts other fields ranging from medicine to the environment. JBIC (Journal of Biological Inorganic Chemistry) seeks to promote this field internationally. The Journal is primarily concerned with advances in understanding the role of metal ions within a biological matrix—be it a protein, DNA/RNA, or a cell, as well as appropriate model studies. Manuscripts describing high-quality original research on the above topics in English are invited for submission to this Journal. The Journal publishes original articles, minireviews, and commentaries on debated issues.