Understanding the direct electron transfer processes between redox proteins and electrode surface is fundamental to understand the proteins mechanistic properties and for development of novel biosensors. In this study, nitric oxide reductase (NOR) extracted from Marinobacter hydrocarbonoclasticus bacteria was adsorbed onto a pyrolytic graphite electrode (PGE) to develop an unmediated enzymatic biosensor (PGE/NOR)) for characterization of NOR direct electrochemical behaviour and NOR electroanalytical features towards NO and O₂. Square-wave voltammetry showed the reduction potential of all the four NOR redox centers: 0.095 ± 0.002, −0.108 ± 0.008, −0.328 ± 0.001 and −0.635 ± 0.004 V vs. SCE for heme c, heme b, heme b₃ and non-heme Fe_B, respectively. The determined sensitivity (−4.00 × 10⁻⁸ ± 1.84 × 10⁻⁹ A/μM and - 2.71 × 10⁻⁸ ± 1.44 × 10⁻⁹ A/μM for NO and O₂, respectively), limit of detection (0.5 μM for NO and 1.0 μM for O₂) and the Michaelis Menten constant (2.1 and 7.0 μM for NO and O₂, respectively) corroborated the higher affinity of NOR for its natural substrate (NO). No significant interference on sensitivity towards NO was perceived in the presence of O₂, while the O₂ reduction was markedly and negatively impacted (3.6 times lower sensitivity) by the presence of NO. These results clearly demonstrate the high potential of NOR for the design of innovative NO biosensors.

了解氧化还原蛋白和电极表面之间的直接电子转移过程是了解蛋白的机械特性和开发新型生物传感器的基础。在这项研究中，从碳氢破壁杆菌细菌中提取的一氧化氮还原酶（NOR）被吸附到热解石墨电极（PGE）上，以开发一种无介导的酶促生物传感器（PGE / NOR）），用于表征NOR的直接电化学行为和NOR对NO的电分析特性和O ₂。方波伏安法显示血红素c，血红素b和血红素b相对于SCE的所有四个NOR氧化还原中心的还原电位：0.095±0.002，-0.108±0.008，-0.328±0.001和-0.635±0.004 V₃和非血红素铁_乙分别。确定的灵敏度（ 对于NO和O ₂分别为-4.00×10 ^-8  ±1.84×10 ^-9  A /μM和-2.71×10 ^-8  ±1.44×10 ^-9 A /μM），检测极限（0.5μM对于NO和O ₂为1.0μM）和米氏常数（分别为NO和O ₂为2.1和7.0μM）证实了NOR对天然底物（NO）的亲和力更高。在O ₂的存在下，没有发现对NO敏感性的显着干扰，而O ₂NO的存在显着而负面地影响了还原效果（灵敏度降低了3.6倍）。这些结果清楚地证明了NOR在设计创新型NO生物传感器方面的巨大潜力。