CHEMICAL & BIO-ORGANIC STUDIES OF VISION & PHOTOTAXIS

化学

• 批准号: 2178426
• 负责人: KOJI NAKANISHI
• 金额: $ 21.94万
• 依托单位: COLUMBIA UNIV NEW YORK MORNINGSIDE
• 依托单位国家: 美国
• 财政年份: 1991
• 资助国家: 美国
• 起止时间: 1991-03-01 至 1995-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2178426
• 关键词: Chlamydomonas; G protein; Halobacteriaceae; Urodela; affinity labeling; all trans retinol; alternatives to animals in research; chemical structure function; cilium /flagellum motility; cis trans isomerization; enzyme mechanism; genetic manipulation; isomerase; molecular cloning; nonvisual photoreceptor; photobiology; protein structure; retinaldehyde; retinoids; rhodopsin; visual perception

Understanding the mechanisms of visual transduction, bleaching adaptation, and microbial phototaxis are all very basic questions intimately related to the process of life. An understanding, if possible, can only be achieved through the efforts of researchers in various areas covering almost the entire field of science. Our efforts will be focused in contributing to this very difficult field mainly through organic and bioorganic approaches. Thus it will necessarily be centered in interpreting and understanding the phenomena on an organic structural basis. As in the past, our major tool will be to use synthetic retinal analogs, the structures of which have been designed so that they can solve specific aspects of these complex phenomena. We have made over 90 different analogs, not counting the cis/trans isomers as separate compounds. Specifically we will investigate the following topics: (a) The tertiary structure of the visual pigment rhodopsin. This is a membrane protein, and despite many efforts it has not been obtained crystalline. We are putting a major effort in mapping out the tertiary structure by a recently developed efficient photoaffinity label, which will be placed in critical sites of the chromophore. (b)The mechanism of bleaching adaptation. This well-known phenomenon is far less understood than the transduction mechanism. We have found a good chemical handle which will for the first time give us a chemical handle to investigate the structural factors of the chromophore that lead to bleaching. (c) The isomerization of vitamin A to 11-cis-retinal, the visual pigment chromophore, is an important step performed by the recently discovered enzyme isomerase. By reacting various analogs with the isomerase, we plan to investigate the details of the isomerase mechanism. (d)The phototaxis of the halophilic bacterium H. halobium depends on two retinal proteins, sensory rhodopsin-I and 11, which cause attractive and repellent movements of the flagella. Again the incorporation of retinal analogs into these photoreceptors has provided us with powerful tools to study the basic mechanism leading to flagella movement. (d)The photoreceptor of the phototactic unicellular algae Chlamydomonas has been found to be most unique in that it is activated by retinal analogs in which the double bonds are fixed so that no isomerization can occur. Furthermore, phototaxis is even induced by simple molecules such as hexanal. We plan to isolate sufficient quantities of the photoreceptor protein, by genomic means or a combination of analog incorporation and molecular biology, so that in vitro biochemical and biophysical measurements can be performed to elucidate these most unexpected results.

了解视觉转导，漂白适应的机制， 和微生物疗法都是与 生活过程。 如果可能的话，只能实现理解 通过在各个领域的研究人员的努力，几乎涵盖了 整个科学领域。 我们的努力将集中于 这个非常困难的领域主要通过有机和生物有机方法。 因此，它必然以解释和理解 有机结构基础的现象。 与过去一样，我们的主要工具 将使用合成视网膜类似物，其结构已 设计以便他们可以解决这些复杂的特定方面 现象。 我们制作了90多种不同的类似物，不计算 顺式/反式异构体作为单独的化合物。 具体我们将调查 以下主题：（a）视觉色素的三级结构 视紫红质。 这是一种膜蛋白，尽管做了很多努力 已获得结晶。 我们正在付出重大努力来绘制 最近开发的有效光性的三级结构 标签，将放置在发色团的关键部位。 （b） 漂白适应机制。 这个众所周知的现象要少得多 比转导机制理解。 我们发现了一个好的化学物质 手柄首次为我们提供化学手柄 研究发色团的结构因素，导致 漂。 （c）维生素A至11- cis的异构化， 视觉色素发色团是最近执行的重要步骤 发现的酶异构酶。 通过反应各种类似物 异构酶，我们计划研究异构酶机制的细节。 （d）卤素细菌H. harobium的发品量取决于两个 视网膜蛋白质，感觉视蛋白I和11，引起吸引力，并且 鞭毛的动作。 再次掺入视网膜 这些光感受器中的类似物为我们提供了强大的工具 研究导致鞭毛运动的基本机制。 （d） 光性单细胞藻类衣原体的光感受器已经 发现最独特的是，它被视网膜类似物激活 双键是固定的，因此不会发生异构化。 此外，光的发品次动物甚至由简单分子（例如）诱导 六边形。 我们计划隔离足够数量的光感受器 蛋白质，通过基因组平均值或类似物的结合和 分子生物学，因此体外生化和生物物理 可以进行测量以阐明这些最出乎意料的结果。