TIME RESOLVED STUDIES OF HELIX COIL TRANSITION IN SMALL PEPTIDES

小肽螺旋线圈转变的时间分辨研究

• 批准号: 8362567
• 负责人: FENG GAI
• 金额: $ 0.65万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-06-01 至 2012-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8362567
• 关键词: Coupled; Diffusion; Funding; Grant; Kinetics; Laboratories; Lasers; Length; Measurement; Methods; Modeling; National Center for Research Resources; Optics; Peptides; Principal Investigator; Process; Proteins; Relaxation; Research; Research Infrastructure; Resources; Role; Series; Source; Theoretical model; Thermodynamics; Time; United States National Institutes of Health; Work; alpha helix; base; cost; infrared spectroscopy; protein folding; temperature jump; time use

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Alpha-helix is a common structural motif in proteins. Understanding its folding mechanism is therefore important for understanding how large proteins fold. The helix-coil transition has been studied extensively in the past, including recent theoretical and experimental efforts as well as studies involving laser-induced T-jump methods. Although a detailed mechanism of the helix-coil transition has begun to emerge, controversy still exists. In this work we are going to study the helix-coil transition in a synthetic 19 residue Ala-based helical peptide using laser-induced T-jump for rapid refolding/unfolding initiation and time-resolved infrared spectroscopy for relaxation measurements. Experimental results will be compared to theoretical model predictions. It is well-known that end caps and the peptide length can dramatically influence the thermodynamics of the helix-coil transition. However, their roles in determining the kinetics of the helix-coil transition have not been studied extensively and are less well understood. Kinetic Ising models and sequential kinetic models involving barrier crossing via diffusion all predict that the helix formation time depends monotonically on the peptide length with the relaxation time increasing with respect to increasing chain length. Here, we have studied the helix-coil transition kinetics of a series of Ala-based alpha-helical peptides of different length (19-39 residues), with and without end caps, using time-resolved infrared spectroscopy coupled with laser-induced temperature jump (T-jump) initiation method.

该子项目是利用资源的众多研究子项目之一 由 NIH/NCRR 资助的中心拨款提供。子项目的主要支持 并且子项目的主要研究者可能是由其他来源提供的， 包括其他 NIH 来源。 子项目可能列出的总成本 代表子项目使用的中心基础设施的估计数量， NCRR 赠款不直接向子项目或子项目工作人员提供资金。 α-螺旋是蛋白质中常见的结构基序。因此，了解其折叠机制对于了解大蛋白质如何折叠非常重要。过去对螺旋-线圈转变进行了广泛的研究，包括最近的理论和实验工作以及涉及激光诱导 T 跳跃方法的研究。尽管螺旋-螺旋转变的详细机制已经开始出现，但争议仍然存在。在这项工作中，我们将研究合成的 19 个残基 Ala 螺旋肽中的螺旋-螺旋转变，使用激光诱导 T 跳跃进行快速重折叠/展开启动，并使用时间分辨红外光谱进行弛豫测量。实验结果将与理论模型预测进行比较。 众所周知，端帽和肽长度可以显着影响螺旋-螺旋转变的热力学。然而，它们在确定螺旋-螺旋转变动力学中的作用尚未得到广泛研究，也不太了解。动力学 Ising 模型和涉及通过扩散跨越势垒的顺序动力学模型都预测，螺旋形成时间单调取决于肽长度，且弛豫时间相对于增加而增加。 链长。在这里，我们使用时间分辨红外光谱结合激光诱导温度研究了一系列不同长度（19-39 个残基）的基于 Ala 的 α 螺旋肽（带或不带端帽）的螺旋-螺旋转变动力学跳跃（T-jump）起始方法。