Chen Yu, Yang Xiao-Jing, Guo Li-Rong, Jin Bo, Xia Xing-Hua, Zheng Li-Min
State Key Laboratory of Coordination Chemistry, Coordination Chemistry Institute, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, PR China.
Talanta. 2009 Apr 15;78(1):248-52. doi: 10.1016/j.talanta.2008.11.006. Epub 2008 Nov 13.
The direct electrochemistry of cytochrome c (cyt c) on a gold electrode modified with 3-mercaptopropylphosphonic acid [HS-(CH(2))(3)-PO(3)H(2), MPPA] self-assembled monolayers (SAMs) was for the first time investigated. Electrochemical measurements and surface-enhanced infrared absorption spectroscopic reveal that the adsorption kinetics of cyt c on the MPPA-SAMs is very fast (saturation adsorption is completed within 5s) and the immobilized cyt c molecules retain their native secondary protein structure. The nature of interaction between cyt c and -PO(3)H(2) groups is mainly the electrostatic interaction. The direct electrochemistry of the immobilized cyt c on the -PO(3)H(2) terminated SAMs with short chain is nearly reversible. Its formal potential (E(0)'=18+/-3 mV vs. SCE) is very close to that of cyt c in an aqueous solution (E(0)'=18-22 mV vs. SCE). In addition, the electron transfer rate of cyt c immobilized on -PO(3)H(2) terminated SAMs is relatively slow as compared to -SO(3)H and -COOH terminated SAMs, indicating excess negative charge density on the SAMs surface will decrease the electron transfer rate of cyt c.
首次研究了细胞色素c（cyt c）在3-巯基丙基膦酸[HS-(CH₂)₃-PO₃H₂，MPPA]自组装单分子层（SAMs）修饰的金电极上的直接电化学。电化学测量和表面增强红外吸收光谱表明，cyt c在MPPA-SAMs上的吸附动力学非常快（5秒内完成饱和吸附），且固定化的cyt c分子保留了其天然的二级蛋白质结构。cyt c与-PO₃H₂基团之间的相互作用性质主要是静电相互作用。固定在短链-PO₃H₂端基SAMs上的cyt c的直接电化学几乎是可逆的。其形式电位（E₀' = 18 ± 3 mV vs. SCE）与水溶液中cyt c的形式电位（E₀' = 18 - 22 mV vs. SCE）非常接近。此外，与-SO₃H和-COOH端基SAMs相比，固定在-PO₃H₂端基SAMs上的cyt c的电子转移速率相对较慢，表明SAMs表面过量的负电荷密度会降低cyt c的电子转移速率。
