MOLECULAR MECHANISMS CONTROLLING BACTERIORHODOPSIN

控制细菌视紫红质的分子机制

• 批准号: 2654985
• 负责人: THOMAS G EBREY
• 金额: $ 12.12万
• 依托单位: UNIVERSITY OF ILLINOIS AT URBANA-CHAMPAIGN
• 依托单位国家: 美国
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-02-01 至 1999-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2654985
• 关键词: Schiff bases; acidity /alkalinity; aminoacid; arginine; aspartate; bacterial pigment; bacteriorhodopsins; chemical kinetics; chromophore; cis trans isomerization; dark adaptation; ion transport; lysine; membrane proteins; molecular dynamics; molecular site; mutant; photochemistry; protonation; temperature; tyrosine; water

The light driven proton pump bacteriorhodopsin is one of the simplest energy conversion devices and ion pumps in nature. The convergence of information on the structure, photochemistry, and proton pumping properties of bacteriorhodopsin make it an ideal protein in which to try to understand the molecular mechanisms controlling a proton pump. Thus, the focus of this application is on the individual amino acids near the Schiff base, the active site of bacteriorhodopsin, from bR's initial state through the transformations that it undergoes after absorbing a photon and as it returns to the initial state. In particular, the following four questions will be probed: 1) What controls the pKa(s) of the Schiff base and of D85, the initial proton acceptor and part of the counter ion to the Schiff base? 2) what controls the rate of dark adaptation, and a related process, the rate of thermal reisomerization of the chromophore at the end of the photocycle? 3). What controls (or causes) the proton movements during the photocycle. For example, does the pK of the Schiff base change during the photocycle? What controls the rate of Schiff base deprotonation, the L to M transition? and 4) what is the proton release group and how is proton release controlled? The following ionizable amino acids near the active site will be studied: tyrosine 57 and 185, arginine 82 and lysine 129, as well as the Schiff base and the aspartic acids 85 and 212. We will manipulate not only the protein part of the pigment but also the light-absorbing chromophore using chemically modified retinals.

轻驱动质子泵细菌紫红质是最简单的一种 能量转换设备和离子泵在自然界中。融合 有关结构，光化学和质子抽水的信息 细菌紫红素的特性使其成为理想的蛋白质 尝试了解控制质子泵的分子机制。 因此，该应用的重点是单个氨基酸 来自BR的Schiff基地附近，细菌淡淡蛋白质的活跃部位 通过其经历的转换的初始状态 吸收光子并返回初始状态。在 特别是，将探讨以下四个问题：1） 控制Schiff底座和D85的PKA（S），初始质子 受体和柜台基地的一部分？ 2）什么 控制黑暗适应的速率和相关过程，速率 发色团在末尾的生物团的热重异构化 光循环？ 3）。什么控制（或原因）质子运动期间的质子运动 光圈。例如，Schiff基地的PK会更改 在光循环期间？是什么控制了席夫基础的速率 去质子化，L到M过渡？ 4）什么是质子 释放组，质子释放如何控制？ 在活性位点附近的以下可离子化氨基酸将是 研究：酪氨酸57和185，精氨酸82和赖氨酸129，以及 Schiff碱和天冬氨酸85和212。我们将操纵 不仅颜料的蛋白质部分，还可以吸收光 发色团使用化学修饰的视网膜。