Bioorganic Studies of Retinal Proteins in Halobacterium halobium (Chemistry)

盐杆菌视网膜蛋白的生物有机研究（化学）

• 批准号: 8718263
• 负责人: Koji Nakanishi
• 金额: $ 27.37万
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1988
• 资助国家: 美国
• 起止时间: 1988-02-01 至 1991-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8718263&HistoricalAwards=false
• 关键词: Bioorganic; Studies; Retinal; Proteins; Halobacterium

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.

在某些细菌的细胞膜中发现的色素具有令人惊讶的化学性质，与动物视觉化学中使用的色素相似。显然，细菌色素的功能与人类眼睛中发现的相应色素的功能大不相同。然而，这两个系统中的一些基本反应在性质上非常相似。有机化学和高分子化学计划中的这一项目旨在研究这些细菌色素生物功能的基础化学。至少有三种以视网膜为发色团的膜蛋白是从古老的盐生细菌中分离出来的：负责跨膜输送质子的细菌视紫红质(BR)，跨膜转运氯离子的卤视紫红质(HR)，以及负责嗜盐梭菌趋光行为的感觉视紫红质(SR)。由于细菌生长在浓缩的氯化钠溶液中，无需太担心污染，而且上述色素是最简单的膜蛋白之一，因此它们非常适合于研究与膜相关的现象。因此，这种颜料引起了各个科学学科的广泛兴趣。目的是从分子结构的基础上研究色素的作用机制，方法是研究已与各种合成视网膜和/或标记氨基酸结合的色素类似物。主要目标是：(I)通过光亲和标记和其他方法确定BR的三级结构；(Ii)描述BR中质子泵浦所需的发色部分的结构因素；以及(Iii)澄清BR内发生的导致质子转移的事件的顺序。还将进行与SR和HR相关的研究。将使用傅里叶变换红外(FTIR)差分光谱以及其他光谱技术。这样的研究将有助于我们理解膜运输，这是一个中心但鲜为人知的主题。