细胞色素c在2-巯基嘧啶衍生物修饰金电极上的直接电化学

Direct electrochemistry of cytochrome c on 2-mercaptopyrimidine derivatives modified gold electrode

用循环伏安法研究了2-巯基嘧啶(MP)、4-氨基-2-巯基嘧啶(AMP)及4,6-二氨基-2-巯基嘧啶(DAMP)自组装修饰金电极的制备及其对细胞色素c直接电子传递的促进作用。用扫描电子显微镜(SEM)表征了2-巯基嘧啶衍生物修饰金电极的表面形貌。细胞色素c在MP、AMP修饰金电极上能进行准可逆的电化学反应,氧化还原峰电位差(ΔEp)分别为61 mV和86 mV,氧化与还原峰电流比ipa/ipc接近1,峰电流与电位扫描速率平方根(v1/2)呈正比,是扩散控制的准可逆过程,异相电子迁移速率常数(Ks)分别为1.4×10-3cm·s-1和5.1×10-5cm·s-1。金电极在2.0 mmol·L-1MP、AMP溶液中分别浸泡3 h和9 h,促进效果较好。随2-巯基嘧啶环上取代氨基数的增加,对细胞色素c电化学反应的促进作用及电极的稳定性逐渐减弱,即MP>AMP,而DAMP基本无促进作用。

2-Mereaptopyrimidine （ MP ）, 4-amino-2-mercaptopyrimidine （ AMP ） and 4,6-diamino-2-mereaptopyrimidine （ DAMP ） modified gold electrodes were prepared by self-assembled monolayer method, and their promotion effects on the direct electron trans- fer of cytochrome c were investigated with cyclic voltammetry. The surface morphology of 2-mercaptopyrimidine derivative modified gold electrodes was characterized by scanning electron microscopy（SEM）. The results shown that cytechrome c can carry out quasi- reversible electrochemical reaction on the MP and AMP modified gold electrodes, the redox potential difference （AEp）was 61 mV and 86 mV, respectively. The redox peak current ratio ip,/ip~ was nearly 1. The peak current was positively correlated to the square root of potential scanning rate（v1/2） ,indicating that it was a diffusion-controlled quasi-reversible process,and the heterogeneous e- lectron migration rate constant（K,）is 1.4×10-3cm·s-1 and 5.1 × 10-5 cm. s-1 , respectively. The optimum promotion effect was ob- tained when the gold electrodes were immersed in 2. 0 mmol -L-1MP or AMP solution for 3 h or 9 h,respectively. The promotion and the stability of 2-mercaptopyrimidine derivatives modified electrodes to the direct electrochemistry of cytechrome c was decreased with the increasing number of amino groups in their molecular structure,i, e. MP〉AMP, but DAMP had almost no promotion.