Electron Transfer Reactions of Proteins and Their Applications in Bioelectrochemistry

本课题主要研究蛋白质的电子转移反应及其应用。在Io_2O_3和启动子修饰电极上研究了纯化过程中获得的三种细胞色素c组分（纯化、脱酰胺和寡聚）的电子转移反应，以阐明细胞色素c纯化过程对快速电子转移的作用。启动子修饰电极也被用于研究细胞色素c赖氨酸残基的来源和修饰对电极反应和蛋白质-蛋白质相互作用的影响。肌红蛋白（来自马热，Mb）首次发现在干净的In_2O_3电极上显示出稳定的氧化还原波。非均相电子转移速率常数（k^<O'>）与溶液的pH有关，pH为6.5时获得>3 × 10^<-4> cm/s的最佳值。在pH为6.5时，再次观察到抹香鲸Mb的最大k^<O'>值，与所使用的Mb的pI值无关（马心：6.8，抹香鲸：8.25）。对于铁氧还蛋白（来自菠菜和玉米，Fd），在少量聚阳离子（如聚l-赖氨酸和聚l-鸟氨酸）存在的情况下，在功能电极上观察到明确的氧化还原波。估计k^<O'>值为>5 × 10^<-3> cm/s。氧化还原波在pH 6 ~ 10范围内稳定。将Fd电化学应用于开发生物电化学系统，利用Fd作为供电子介质进行适合于自然界光合系统的酶反应。此外，本项目还开发了新的光谱电化学技术，并将其应用于研究生物分子的电子传递反应，并利用Meldola蓝掺入十硫醇修饰的金电极建立了具有电子传递功能的细胞膜模型。

In the present research project, electron transfer reactions of proteins and their applications have been studied.Electron-transfer reactions of three components (purified, deamidated and oligomeric) of cytochrome c obtained in the purification procedure have been examined at both Io_2O_3 and promoter modified electrodes to clarify the role of the purification procedure of cytochrome c for the rapid electron transfer. Promoter-modified electrodes have also been applied to study effects of origin and modification of lysine residues of cytochrome c on the electrode reaction and protein-protein interactions.Myoglobin (from horse heat, Mb) has found to show a stable redox wave at a clean In_2O_3 electrode, for the first time. The heterogeneous electron-transfer rate constant(k^<O'>)depended on the pH of the solution, and >3 x 10^<-4> cm/s was obtained at pH 6.5 as the best value. The largest k^<O'> value was again observed for sperm whale Mb at pH 6.5 independent of the pI values of Mb used(horse heart : 6.8, sperm whale : 8.25).For ferredoxin (from spinach and maize, Fd), well-defined redox wave was found to be observed at functional electrodes in the presence of small amounts of polycations, such as poly-L-lysine and poly-L-ornithine. The k^<O'> value was estimated to be >5 x 10^<-3> cm/s. The redox wave was stable in the pH 6 to 10 region. Electrochemistry of Fd was applied to develop bioelectrochemical systems using Fd as an electron-donating mediator for suitable enzyme reactions as in the photosynthetic systems in nature.Also, in the present research project, new spectroelectrochemical techniques have been developed and applied to study the electron transfer reactions of biological molecules, and a model of cell membrane having a function of electron transport was developed using a Meldola's blue incorporated decanethiol modified gold electrode..