FEMTO/PICOSECOND LASER SPECTROSCOPY OF RHODOPSINS

描述：(改编自调查人员摘要) 脊椎动物和无脊椎动物都是由光异构化引发的 在跨膜蛋白视紫红质中的视网膜发色团。在.期间 在毫微微/皮秒内发生的初始分子事件，如 异构化(和由此产生的电荷分离)有效地存储了 通过发色团-蛋白质相互作用的入射光能 周围的蛋白质。这种能量的储存是以后 涉及蛋白质-蛋白质相互作用的视觉级联中的步骤，例如 G蛋白(转运蛋白)与视紫红质表面的结合。 这项拟议的研究检查了飞秒/皮秒光化学 室温下视网膜视紫红质，以阐明：(I)光- 诱导发色团本身的结构变化和(Ii)视网膜- 不同视网膜构象选择性地通过蛋白质相互作用 与周围的蛋白质相互作用。它的分子机制 这两种现象都参与和/或与初级 存储和转换吸收的光能的光化学事件将是 学习。待检测的样本包括牛视紫红质(用 天然类脂和合成洗涤剂)和人造视紫红质 用化学发色团取代天然发色团合成的颜料 改良的视网膜。 飞秒/皮秒激光技术将用于测量 用瞬变吸收光谱和荧光光谱研究电子态 以及视网膜多烯结构的时间分辨变化 共振拉曼散射。因此，拟议的研究方案结合了 飞秒/皮秒激光光谱学与先进的化学方法 多烯合成及人工视紫红质色素的制备。 在一项必然的活动中，原发视网膜和 发色团-蛋白质在蛋白质-蛋白质相互作用中的事件，如G- 蛋白质结合的探索将通过与 快速动力学结果与G蛋白激活和 选定视紫红质样品的表面结合特性。

DESCRIPTION: (Adapted from investigator's abstract) Visual processes in both vertebrates and invertebrates are initiated by the photo-isomerization of retinal chromophore in the trans-membrane protein, rhodopsin. During the initial molecular events occurring within femto/picoseconds, such isomerizations ( and resultant charge separation) efficiently stores the incident light energy via chromophore-protein interactions with the surrounding protein. This storage of energy is a prerequisite for later steps in the visual cascade involving protein-protein interactions such as the binding of a G-protein (tansducin) at the rhodopsin surface. The proposed research examines the femto/picosecond photochemistry of retinal in room temperature rhodopsin in order to elucidate: (i) light- induced structural changes in the chromophore itself and (ii) retinal- protein interactions by which different retinal conformations selectively interact with the surrounding protein. The molecular mechanism by which both phenomena participate and/or an correlated with the primary photochemical events to store and transduce absorbed light energy will be studied. Samples to be examined include bovine rhodopsin (prepared with both native lipids and synthetic detergents) and artificial rhodopsin pigments synthesized by replacing the native chromophore with chemically- modified retinals. Femto/picosecond laser techniques will be used to measure changes in electronic states by transient absorption and fluorescence spectroscopy as well as changes in the polyene structure of retinal by time-resolved resonance Raman scattering. The proposed research program thereby combines femto/picosecond laser spectroscopy with advance chemical methodologies in polyene synthesis and the preparation of artificial rhodopsin pigments. In a corollary activity, the overall influence of the primary retinal and chromophore-protein events on protein-protein interactions such as G- protein binding will be explored through a collaboration in which with the fast dynamical results are correlated with G-protein activation and surfaced binding properties of selected rhodopsin samples.