Sun Wei, Han Junying, Jiao Kui, Lu Lude
College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042, China.
Bioelectrochemistry. 2006 Jan;68(1):60-6. doi: 10.1016/j.bioelechem.2005.03.007. Epub 2005 Jun 6.
An electrochemical investigation on the interaction of acid chrome blue K (ACBK) with protein on the mercury electrode with different electrochemical methods such as cyclic voltammetry and linear sweep voltammetry was reported in this paper. In pH 3.0 Britton-Robinson (B-R) buffer solution, ACBK has an irreversible voltammetric reductive peak at -0.23 V (vs. SCE). The addition of human serum albumin (HSA) into the ACBK solution resulted in the decrease of reductive peak currents without the change of the peak potential and no new peaks appeared on the cyclic voltammogram. In the absence and presence of HSA, the electrochemical parameters such as the formal potential E0, the electrode reaction standard rate constant k(s) and the charge transfer coefficient alpha of the interaction system were calculated and the results showed that there were no significant changes between each other. Thus, the interaction of ACBK with protein forms an electro-inactive supramolecular bio-complex, which induces the decrease of the free concentration of ACBK in the reaction solution, and the decrease of the reductive peak current of ACBK. The binding constant and the binding ratio are calculated as 1.29 x 10(8) and 1:2, respectively, and the interaction mechanism is discussed. Based on the binding reaction, this new electrochemical method is further applied to the determination of HSA with the linear range from 3.0-20.0 mg/L and the linear regression equation as deltaIp"(nA) = 10.08 + 19.90 C (mg/L). This method was further applied to determinate the content of protein in the healthy human serum samples with the results in good agreement with the traditional Coomassie brilliant blue G-250 spectrophotometric method.
本文报道了采用循环伏安法和线性扫描伏安法等不同电化学方法，在汞电极上对酸性铬蓝K（ACBK）与蛋白质相互作用进行的电化学研究。在pH 3.0的 Britton-Robinson（B-R）缓冲溶液中，ACBK在-0.23 V（vs. SCE）处有一个不可逆的伏安还原峰。向ACBK溶液中加入人血清白蛋白（HSA）后，还原峰电流降低，峰电位不变，循环伏安图上未出现新峰。在有无HSA的情况下，计算了相互作用体系的形式电位E0、电极反应标准速率常数k(s)和电荷转移系数α等电化学参数，结果表明彼此之间无显著变化。因此，ACBK与蛋白质的相互作用形成了一种电惰性的超分子生物复合物，导致反应溶液中ACBK的游离浓度降低，ACBK的还原峰电流减小。计算得到结合常数和结合比分别为1.29×10(8)和1:2，并对相互作用机理进行了讨论。基于该结合反应，将这种新的电化学方法进一步应用于HSA的测定，线性范围为3.0 - 20.0 mg/L，线性回归方程为ΔIp"(nA) = 10.08 + 19.90 C (mg/L)。该方法进一步应用于健康人血清样品中蛋白质含量的测定，结果与传统的考马斯亮蓝G-250分光光度法吻合良好。
