STRUCTURE/FUNCTION OF COLOR VISION PIGMENTS

视觉科学的核心问题之一是光谱的机制 在视觉颜料中调谐。为什么吸收极大值可以 当实际分子吸收时，范围从380 nm到600 nm以上 光，11顺式视网膜生色团，在所有的色素中都是相同的吗？ 显然，视网膜发色团与氨基酸之间存在相互作用。 改变光谱特性的蛋白质中的侧链 生色团。这些研究的目的就是解开这些机制 一个定义非常明确的实验系统：人类的色觉 颜料。 这项工作将集中在这些蛋白质中已知的三组氨基酸上 要深刻影响发色团的光谱性质：1) 造成红色和绿色光谱差异的7种氨基酸 2)生色团的质子化席夫碱和席夫碱 反离子；3)红色和绿色颜料的氯结合部位。 该方法将使用定点突变，化学 蛋白质的修饰，以及生色团类似物与 纯化色素的体外表征。 由于最近在应用方面的技术突破， 共振拉曼光谱来研究这些颜料，这种强大的 将广泛使用光谱分析工具来探测 视网膜生色团存在于这项工作的方方面面。的巨大潜力 这个应用程序显然是从一个认识到，视觉的来源 用于拉曼研究的色素将是一个包含150多个突变体的文库 蓝色、绿色和红色的视觉颜料是在原始的基础上构建的 授权期。

One of the central problems in visual science is the mechanism of spectral tuning among the visual pigments. How is it that the absorption maxima can range from 380 nm to over 600 nm when the actual molecule that absorbs light, the 11-cis-retinal chromophore, is identical in all of the pigments? Clearly, there are interactions of the retinal chromophore with amino acid sidechains in the proteins that modify the spectral properties the chromophore. It is the purpose these studies to unravel these mechanisms for one extremely well defined experimental system: the human color vision pigments. This work will focus on three groups of amino acids in these proteins known to profoundly affect the spectral properties of the chromophore: 1) the 7 amino acids that cause the spectral difference between the red and green pigments; 2) the protonated Schiff base of the chromophore and Schiff base counterion; and 3) the chloride binding site of the red and green pigments. The approach will be to use site-directed mutagenesis, chemical modification of the proteins, and chromophore analogs in combination with in vitro characterization of the purified pigments. As a result of a recent technical breakthrough in the application of resonance Raman spectroscopy to the study of these pigments, this powerful spectroscopic tool will be used extensively to probe the structure of the retinal chromophore in all aspects of this work. The enormous potential of this application is apparent from a realization that the source of visual pigment for the Raman studies will be a library of over 150 mutants in the blue, green and red visual pigments that was constructed over the original grant period.