Department of Chemistry, University of Isfahan, Isfahan 81746-73441, I.R. Iran.
Department of Chemistry, University of Isfahan, Isfahan 81746-73441, I.R. Iran.
Bioelectrochemistry. 2014 Aug;98:53-63. doi: 10.1016/j.bioelechem.2014.03.004. Epub 2014 Mar 19.
Direct electrochemistry of cytochrome c (Cyt c) is achieved via Zr(IV) ion as an immobilization matrix to interface Cyt c on gold surface via thiol self-assembled monolayers. Steps of surface modification and electrocatalytic activity of the immobilized Cyt c are followed by voltammetry, impedance spectroscopy, chronoampetrometry, and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. The results indicate that the native structure of Cyt c is conserved during the immobilization process. The immobilization method is rather simple, effective and free of immobilizing activators and reagents. Direct electron transfer rate constant and surface coverage of the immobilized Cyt c are found as 8.62(±1.98) s(-1) and 1.15(±0.38)×10(-11)molcm(-2), respectively. Bioactivity studies of the immobilized Cyt c toward oxidation of the ascorbic acid (AA) substrate show a linear response, from 10.0μM to 1.30mM AA, with a detection limit of 5.0(±1.8) μM AA and mean relative standard deviations varied from 13.7% to 3.7% for n=4 at each point. A value of 1.6(±0.8) mM AA is found for the Michaelis-Menten constant of Au-MPA-Zr(IV)-Cyt c toward AA for the first time. The tightly immobilized Cyt c maintains its bioactivity for more than 32days storage at 4°C.
通过 Zr(IV) 离子作为固定化基质，实现细胞色素 c (Cyt c) 的直接电化学。细胞色素 c 通过硫醇自组装单层固定在金表面。通过伏安法、阻抗谱、计时安培法和衰减全反射傅里叶变换红外（ATR-FTIR）光谱法跟踪表面修饰和固定化 Cyt c 的电催化活性。结果表明，Cyt c 的天然结构在固定化过程中得以保留。固定化方法简单、有效，无需固定化激活剂和试剂。固定化 Cyt c 的直接电子转移速率常数和表面覆盖率分别为 8.62(±1.98)s(-1)和 1.15(±0.38)×10(-11)molcm(-2)。固定化 Cyt c 对抗坏血酸 (AA) 底物氧化的生物活性研究表明，线性响应范围从 10.0μM 到 1.30mM AA，检测限为 5.0(±1.8)μM AA，在每个点处 n=4 的平均相对标准偏差从 13.7%变化到 3.7%。首次发现 Au-MPA-Zr(IV)-Cyt c 对 AA 的米氏常数为 1.6(±0.8)mM AA。固定化 Cyt c 在 4°C 下储存超过 32 天仍保持其生物活性。
