Fast Kinetic Studies of Protein Folding and Function

蛋白质折叠和功能的快速动力学研究

• 批准号: 6874802
• 负责人: DAVID S. KLIGER
• 金额: $ 32.59万
• 依托单位: UNIVERSITY OF CALIFORNIA SANTA CRUZ
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-09-01 至 2008-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6874802
• 关键词: allosteric site; chemical kinetics; circular magnetic dichroism; conformation; cytochrome c; cytochrome oxidase; electron transport; hemoglobin; hemoprotein structure; myoglobin; optical rotation; photolysis; protein folding; protein structure function; structural biology; time resolved data; ultraviolet radiation

DESCRIPTION (provided by applicant): This project applies techniques for fast time-resolved magnetic circular dichroism (TRMCD), natural circular dichroism (TRCD, and ordinary absorption spectroscopies to the study of function in heme proteins and folding in heme proteins and small peptides. The novel optical methods employed use near-null ellipsometry and polarimetry to study rapid kinetic processes (nanosecond to seconds) in biomolecules that contain magneto-optically active chromophores, such as heme and the aromatic amino acids, and naturally chiral chromophores, such as the amide groups of proteins and peptides. These techniques will be used to identify and study the earliest (submillisecond) events in the folding reactions of heme proteins such as cytochrome c. A major goal is the determination of a parameter that is fundamental to understanding the nature of protein folding: the speed with which the different unfolded conformations interconvert with one another. If this is slow compared to folding itself, then understanding protein folding will require more complicated theories (e.g., energy landscape) than the transition state theory used for typical chemical reactions. Such understanding may ultimately prove helpful in developing therapies for the many diseases associated with protein misfolding, such as cystic fibrosis, type 2 diabetes, and Alzheimer's, Parkinson's, and Creutzfeldt- Jakob disease. A major goal of the functional studies is to understand how the four subunits that make up the hemoglobin molecule cooperate with each other to transport oxygen more efficiently. A recent hypothesis about this cooperativity (Ackers symmetry rule), based originally on thermodynamic measurements, is tested by kinetic measurements in this project. A novel model for hemoglobin allostery, emerging from this linkage of thermodynamics and kinetics, holds promise for simplifying and systematizing our understanding of hemoglobin's dynamics and its control in the body by allosteric effectors such as organic phosphates. In addition, TRMCD studies of the aromatic amino acid residue tryptophan [337, positioned at a site critical for cooperativity, are intended to further clarify how hemoglobin's subunits work together as an efficient "molecular machine" for transporting oxygen from the lungs to the tissues.

描述（由申请人提供）：该项目将技术应用于快速分辨的磁循环二色性（TRMCD），自然圆形二分法（TRCD和普通吸收光谱型在血红素蛋白质中的研究中，以及在血红素蛋白和小型肽中折叠的功能研究。 （纳秒至秒）在包含磁性活跃的发色团（例如血红素和芳族氨基酸）的生物分子中，以及自然的手性发色团，例如蛋白质的酰胺基团，例如蛋白质和肽。确定一个参数是理解蛋白质折叠的性质的基础：如果与折叠本身相比，不同的构象相互互动的速度，那么了解蛋白质折叠将需要比用于典型化学反应的过渡状态理论更复杂的理论（例如能量景观）。这种理解最终可能证明有助于开发与蛋白质错误折叠相关的许多疾病的疗法，例如囊性纤维化，2型糖尿病，阿尔茨海默氏症，帕金森氏症和克鲁特兹菲尔德氏病。功能研究的主要目标是了解组成血红蛋白分子的四个亚基如何相互配合以更有效地运输氧气。该项目的动力学测量值测试了有关这种合作性（Ackers对称规则）的最新假设（Ackers对称规则）。一种新型的血红蛋白变构模型，从这种热力学和动力学的联系中浮现出来，有望通过诸如有机磷酸盐等变构效应子来简化和系统化我们对血红蛋白动力学及其在体内的控制。此外，对芳族氨基酸残基色氨酸的TRMCD研究[337位于至关重要的合作性的地点，旨在进一步阐明血红蛋白的亚基如何作为有效的“分子机”一起运输，以将氧气从肺部运输到组织。