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.

光驱动质子泵细菌视紫红质是最简单的 能量转换装置和离子泵。的收敛性 关于结构、光化学和质子泵的信息 细菌视紫红质的特性使其成为理想的蛋白质， 试图理解控制质子泵的分子机制。 因此，本申请的重点是单个氨基酸 在席夫碱附近，细菌视紫红质的活性部位，来自bR的 初始状态，通过它经历的转变， 吸收一个光子并返回到初始状态。在 具体而言，将探讨以下四个问题：1）什么 控制席夫碱和D85（初始质子）的pKa 受体和部分反离子的席夫碱？2)什么 控制暗适应的速率，以及相关的过程， 发色团的热再异构化的末端， 光循环？3）。是什么控制（或导致）了质子的运动？ 光循环例如，席夫碱的pK是否改变 在光循环中？是什么控制了席夫碱的生成速率 去质子化，L到M的转变？4）质子是什么 释放组和如何控制质子释放？ 在活性位点附近的以下可电离氨基酸将是 研究：酪氨酸57和185，精氨酸82和赖氨酸129，以及 席夫碱和天冬氨酸85和212。我们将操纵 不仅色素的蛋白质部分， 使用化学修饰的视网膜的发色团。