Bioorganic Studies of Retinal Proteins in Halobacterium halobium (Chemistry)

在某些细菌的细胞膜中发现的色素 化学性质与所用颜料惊人地相似， 在动物视觉的化学中。细菌色素 显然有着与 在人眼中发现的相应色素。但部分 两个系统的基本反应非常相似， 自然 这个项目在有机和大分子 化学课程旨在研究基本的 这些细菌的生物功能的化学 颜料. 至少有三种膜蛋白具有视网膜作为 从这种古老的细菌中分离出了发色团 盐生盐杆菌：细菌视紫红质（bR）， 质子穿过膜，盐视紫红质（hR）， 使氯离子穿过细胞膜， 视紫红质（sR），负责趋光性 H的行为。盐生菌。 因为细菌生长在 浓氯化钠溶液，不用担心 污染，并且由于上述颜料是 在最简单的膜蛋白中， 适用于研究膜相关现象。 颜料 因此吸引了各种科学家的广泛兴趣 学科 目的是探讨其作用机制， 颜料在分子结构基础上起作用， 方法是研究已经被 与各种合成视黄醇结合和/或标记 个氨基酸 主要目标是：（一）确定 通过光亲和标记和其他方法测定bR三级结构 （二）结构性因素的界定; bR中质子泵送所需的发色团部分;和 (iii)澄清事件发生的顺序， bR导致质子的转移。 sR相关研究 hR也将被执行。 傅里叶变换红外 （FTIR）差光谱以及其他光谱分析技术。 技术将被使用。 这些研究将有助于我们 膜运输的理解，一个中心，但很少 理解的主题。

Pigments found in the membranes of certain bacteria are of a chemical nature surprisingly like that of pigments employed in the chemistry of vision in animals. The bacterial pigments clearly have a much different function than do the corresponding pigments found in the human eye. However, some of the fundemental reactions in both systems are very similar in nature. This project in the Organic and Macromolecular Chemistry Program is designed to investigate the basic chemistry of the biological function of these bacterial pigments. At least three membrane proteins possessing retinal as the chromophore have been isolated from the ancient bacterium Halobacterium halobium: bacteriorhodopsin (bR) which pumps protons across the membrane, halorhodopsin (hR) which translocates chloride ions across the membrane, and sensory rhodopsin (sR) which is responsible for the phototactic behavior of H. halobium. Because the bacteria are grown in concentrated sodium chloride solution without much fear of contamination, and because the above-mentioned pigments are among the simplest of membrane proteins, they are ideally suited for studying membrane related phenomena. The pigments are thus attracting wide interest from the various scientific disciplines. The objective is to investigate the mechanism of the pigment functions on a molecular structural basis, the approach being studies on pigment analogs that have been incorporated with various synthetic retinals and/or labeled amino acids. The main targets are: (i) determination of the tertiary structure of bR by photoaffinity labeling and other means; (ii) delineation of structural factors of the chromophoric moiety required for proton pumping in bR; and (iii) clarification of the sequence of events occurring within bR leading to the transfer of protons. Related studies with sR and hR will also be performed. Fourier transform infrared (FTIR) difference spectroscopy as well as other spectroscopic techniques will be used. Such studies will contribute to our understanding of membrane transport, a central but little understood theme.