MECHANISM OF CHLORIDE TRANSPORT BY HALORHODOPSIN

我们将继续研究光驱动的氯离子 泵，盐视紫红质，并试图阐明其结构， 光化学反应和离子的机理 易位 我们的中心假设是， 在光循环中检测到两个氯离子依赖平衡 方案对应于两个上的吸收和释放位点 蛋白质的两侧，穿过膜屏障。 我们打算 批判性地检验这一假设，将其发展成一个通用模型， 为氯离子泵，并提供实验证据， 用更分子的术语来描述它。 结构模型， 蛋白质（MW 25，000），基于最近测定的氨基酸 酸序列，将被细化，至于螺旋的位置， 循环 我们将尝试用光谱法定位这三个 检测到相对于蛋白质残基的氯离子结合位点， 视网膜，并建立这些网站的作用， 运输 光循环中的氯离子易位事件 将根据配置变化进行识别 视网膜 蛋白质的构象变化 寻求，可能与氯化物结合和释放有关。 低聚物结构在功能性质中的作用将是 分析了

We will continue our studies of the light-driven chloride ion pump, halorhodopsin, and attempt to elucidate its structure, photochemical reactions, and the mechanism of the ion translocation. Our central hypothesis at this time is that the two chloride-dependent equilibria detected in the photocycle scheme correspond to the uptake and release sites on the two sides of the protein, across the membrane barrier. We intend to critically test this hypothesis, elaborate it into a general model for the chloride pump, and provide experimental evidence for stating it in more molecular terms. A structural model for the protein (MW 25,000), based on the recently determined amino acid sequence, will be refined, as to the location of helices and loops. We will attempt to localize the three spectroscopically detected chloride binding sites relative to protein residues and the retinal, and to establish the role of these sites in the transport. The chloride translocation event in the photocycle will be identified, in relation to the configurational changes of the retinal. Conformational changes in the protein will be sought, with possible relevance to chloride binding and release. The role of oligomeric structure in functional properties will be analyzed.