Raman Spectroelectrochemical Study on Bioactive Molecules

本文概述了采用电化学现场拉曼光谱技术研究氧化物歧化酶在L 半胱氨酸修饰金电极表面的电子迁移反应以及腺嘌呤共存条件下超氧化物歧化酶在金电极表面的电子迁移反应和不同电位下银电极表面烟酰胺腺嘌呤二核苷酸的吸附等体系的反应吸附特性 .所得结果对于分析和研究生物活性分子电化学过程机理具有重要意义 .Electron?transfer reaction is known to be one of the key reactions for generating biological functions. Mechanism revelation at a molecular level of such kind reactions is to be very helpful for us to understand life essence. In fact, surface enhanced Raman scattering (SERS) is one of the most powerful tools for the study on metal?electrolyte and metal?vacuum interfaces since 1970's. Moreover, Raman spectroscopic study in enzymology has provided attractive results during last twenty?five years. For the study of electron?transfer reaction mechanism of some oxidoreductases and SERS of some other biological macromolecules, an electrochemical in situ Raman spectroscopic technique was established in author's lab and some research works have been done on it in the past two years. A brief review of these works is given in this paper. The electrochemical in situ Raman spectroscopic measurements were carried out using a Super LABRAM Raman spectrometer (Dilor, France) coupled with a CHI604A Electrochemical Analyzer (CH Instr., USA). A Teflon spectroelectrochemical cell with a quartz plate window was designed for the in situ measurements. The working electrode was pretreated with oxidation?reduction cycles for each measurement. The electrolyte solutions were purged with nitrogen prior to all measurements, and all the measurements were carried out under the nitrogen atmosphere. Copper, zinc superoxide dismutase (SOD) is an important oxidoreductase for organism metabolism. The established spectroelectrochemical technique was first used to characterize the cyclic voltammetric process of SOD at L?cysteine modified gold electrode as well as the process of electrochemical modification of L?cysteine molecules on a gold electrode. The obtained Raman spectra reveal that the L?cysteine modified gold electrode improves effectively the reversibility of electron?transfer reactions of SOD. Besides L?cysteine molecules, it was interesting that adenine was also an effective electron?transfer promoter for SOD at gold electrode. A strong peak at 355 cm -1 can be observed in the Raman spectrum of adenine molecules adsorbed on gold electrode. It was inferred that the peak maybe related to the chemical interaction between adenine molecules adsorbed and gold electrode surface. As shown in Fig.1, for the mixture of SOD and adenine at gold electrode under a polarization potential 55 mV (vs. SCE), both the characteristic Raman lines of SOD and adenine molecules appeared. Therefore it was reasonable to conclude that SOD and adenine molecules should be co?adsorbed on gold electrode surface under such a potential, which is slightly lower than the reduction peak potential of SOD on adenine?modified gold electrode. Moreover, two new peaks appeared remarkably at 445 cm -1 and 610 cm -1 are likely to be related to the active site of SOD. It suggests that the co?adsorption mechanism of SOD and adenine molecules on the gold electrode surface results in effective approaching of the active site of SOD to the electrode surface.作者联系地址：上海师范大学化学系!上海200234,上海师范大学化学系!上海200234,上海师范大学化学系!上海200234,上海师范大学化学系!上海200234,上海师范大学化学系!上海200234,上海师范大学化学系!上海200234Author's Address: Dept. of Chem., Shanghai Teachers Univ., Shanghai 200234,Chin

Electrochemical Quartz Crystal Microbalance Study on the Promoted Electron Transfer Process at Gold Electrode

本文比较了L_半胱氨酸、组氨酸和精氨酸等三种氨基酸在石英晶体微天平金电极上的吸附行为 .重点考察了超氧化物歧化酶在L_半胱氨酸存在的混合溶液中以及事先经L_半胱氨酸修饰的金晶振电极上的循环伏安曲线和频率响应曲线 .实验结果表明 ,超氧化物歧化酶在L_半胱氨酸修饰的金晶振电极上的电子传递过程是一个准可逆过程 ,它同时对应于一个可逆的吸脱附过程 .初步讨论了L_半胱氨酸对超氧化物歧化酶电子传递过程的促进机制 .The adsorption behavior of amino acids, such as L_cysteine, histidine and arginine at gold_quartz crystal microbalance (Au_QCM) was investigated. The adsorption quantity of cysteine is more appreciable than others because of the stronger interaction between its thiol group and the gold electrode surface. The electron_transfer process of superoxide dismutase(SOD) in presence of cysteine at Au_QCM has also been studied using the electrochemical quartz crystal microbalance (EQCM) technique which reveals clearly the quasi_reversible electron_transfer process accompanied by the frequency shift cycle. The reversible adsorption and disorption processes are discussed.作者联系地址：上海师范大学化学系!上海200234,上海师范大学化学系!上海200234,上海师范大学化学系!上海200234,上海师范大学化学系!上海200234Author's Address: Dept. of Chem., Shanghai Teachers Univ., Shanghai 200234, Chin

A study of the Adsorption Behaviors on the Surface of Gold electrode by In-situ Electrochemical Raman Spectroscopy

报道腺嘌呤在裸金电极及其修饰的金电极上的电化学原位拉曼光谱图 ,着重分析了不同电位下腺嘌呤和超氧化物歧化酶在金电极上的吸附及其相互作用 ,初步讨论了腺嘌呤对促进超氧化物歧化酶电子传递过程的作用机制 .The results of in situ measurements with Raman spectroelectrochemical thchnique on bare gold electrode and adenine modified gold electrode were reported. The adsorption behaviors of adenine and superoxide dismutase(SOD) and their interactions with gold electrode were analyed. The mechanism of promoted electron transfer process of SOD in the presence of adenine at gold electrode surface is discussed.作者联系地址：上海师范大学化学系!上海200234,上海师范大学化学系!上海200234,上海师范大学化学系!上海200234,上海师范大学化学系!上海200234,上海师范大学化学系!上海200234Author's Address: Dept. of Chem., Shanghai Teachers Univ., Shanghai 200234 Chin

The Electrochemical Behaviors of Superoxide Dismutase at Promoter Modified Gold Electrode

　应用循环伏安法探索了超氧化物歧化酶在Ｌ＿半胱氨酸、组氨酸和精氨酸等氨基酸修饰的金丝电极上的电化学行为．实验结果表明，Ｌ＿半胱氨酸是超氧化物歧化酶的有效促进剂．组氨酸和精氨酸则对超氧化物歧化酶氧化过程显示了不同程度的促进作用．此外，还讨论了４ ，４＿二硫基联吡啶对超氧化物歧化酶电子传递过程的促进作用The electron_transfer process of superoxide dismutase was investigated by cyclic voltammetry at the 4,4'_dithiodipyridine,L_cysteine,histidine and arginine modified gold wire electrodes repectively.The quasi_reversible behavior was observed at L_cysteine modified gold electrode.An irreversible electrochemical behavior has been observed at hisdinine modified gold wire electrode.作者联系地址：上海师范大学化学系!上海200234,上海师范大学化学系!上海200234,上海师范大学化学系!上海200234,上海师范大学化学系!上海20023