Nitrate reductase (NR) from the fungus Neurospora crassa is a complex homodimeric metallo-flavoenzyme, where each protomer contains three distinct domains; the catalytically active terminal molybdopterin cofactor, a central heme-containing domain, and an FAD domain which binds with the natural electron donor NADPH. Here, we demonstrate the catalytic voltammetry of variants of N. crassa NRs on a modified Au electrode with the electrochemically reduced forms of benzyl viologen (BV²⁺) and anthraquinone sulfonate (AQS⁻) acting as artificial electron donors. The biopolymer chitosan used to entrap NR on the electrode non-covalently and the enzyme film was both stable and highly active. Electrochemistry was conducted on two distinct forms; one lacking the FAD cofactor and the other lacking both the FAD and heme cofactors. While both enzymes showed catalytic nitrate reductase activity, removal of the heme cofactor resulted in a more significant effect on the rate of nitrate reduction. Electrochemical simulation was carried out to enable kinetic characterisation of both the NR:nitrate and NR:mediator reactions.

来自真菌Neurospora crassa的硝酸还原酶（NR）是一种复杂的同型二聚金属黄酮酶，其中每个启动子都包含三个不同的结构域。催化活性的末端钼蝶呤辅因子，一个含血红素的中央结构域和一个与天然电子供体NADPH结合的FAD结构域。在这里，我们展示了N变体的催化伏安法。粗糙脉孢菌卢比上的改性的Au电极用苄基紫精的电化学还原形式（BV ²⁺）和蒽醌磺酸（AQS ^-）充当人造电子供体。生物聚合物壳聚糖用于将NR非共价地捕获在电极上，并且酶膜既稳定又具有高活性。电化学以两种不同的形式进行；一个缺少FAD辅助因子，另一个缺少FAD和血红素辅助因子。尽管两种酶均显示出催化的硝酸盐还原酶活性，但血红素辅因子的去除对硝酸盐的还原速率产生了更显着的影响。进行了电化学模拟，以实现NR：硝酸盐和NR：介体反应的动力学表征。