RESONANCE RAMAN STUDIES OF RHODOPSIN & RELATED PIGMENTS

我们希望了解视觉传导的分子基础。 特别是，我们打算深入研究（1）关键光， 化学能量转换步骤，将视紫红质转化为视紫红质 转换，以及（2）转导素化学中的第一步 级联反应导致视杆细胞超极化， 由兴奋的视紫红质催化 为了完成这些 目标，我们在这里提出了几个实验，采用国家的- 最先进的光谱技术， 分子信息 共振拉曼和非常快 （亚皮秒和皮秒）吸收和荧光 技术将被用来研究视紫红质到视紫红质 光反应 章鱼的共振拉曼光谱 视紫红质和视紫红质以及同位素标记 而昆虫视紫红质，Ascalaphus macaronius， 为了观察分子概念的发展， 因为研究得很好的牛系统可以推广到不同的 物种 视紫红质向视紫红质的转变尚未被发现。 动力学解析 关于质子是否 伴随视紫红质易位为视紫红质 光反应和理解分子动力学 台阶只能通过动力学测量获得。 我们认为 我们的0.2皮秒吸收光谱仪应该能够分辨出 这关键一步。 本提案中描述的最新颖的工作是 高灵敏度经典拉曼差分的应用 技术，最近在我们的实验室开发，以获得 GDP和GTP与转导素、T. T.GDP+GTP的交换反应产生T.GTP+GDP， 是光放大的第一步 吸收事件 结合态GDP和GTP的拉曼光谱 应该提供了大量的信息， 会发生

We wish to understand the molecular basis of visual transduction. In particular, we intend to study in depth (1) the key light to chemical energy conversion step, the rhodopsin to bathorhodopsin transition, and (2) the first steps in the transducin chemical cascade reaction leading to rod cell hyperpolarization which is catalyzed by excited rhodopsin. In order to accomplish these goals, we propose here several experiments employing state-of- the-art spectroscopic techniques which yield very detailed molecular information. Resonance Raman and very fast (subpicosecond and picosecond) absorption and fluorescence techniques will be used to study the rhodopsin to bathorhodopsin photoreaction. The resonance Raman spectra of octopus rhodopsin and bathorhodopsin, and isotopically labelled derivatives, and the insect rhodopsin, Ascalaphus macaronius, will be obtained in order to see if the molecular concepts developed for the well studied bovine system can be generalized to different species. The rhodopsin to bathorhodopsin transition has not been kinetically resolved. Knowledge of whether or not proton translocation accompanies the rhodopsin to bathorhodopsin photoreaction and understanding the molecular dynamics of this step can only be obtained by kinetic measurements. We believe our 0.2 psec absorption spectrometer should be able to resolve this key step. The most novel work described in this proposal is the application of very sensitive classical Raman difference techniques, recently developed in our laboratory, to obtain the Raman spectra of GDP and GTP when bound to transducin, T. The exchange reaction T.GDP+GTP yields T.GTP+GDP, catalyzed by excited rhodopsin, is the first step in amplification of the light absorption event. The Raman spectra of bound GDP and GTP should provide a great deal of information on how the reaction takes place.