Peptide Dynamics Investigated by 13C and 15N-NMR Relaxation

9729539梅奥表征蛋白质和多肽的部分折叠和特别是未折叠状态，由于它们的瞬时性质，一直是有问题的。~(13)C/~(15)N核磁共振弛豫特别适合于研究这些状态。本项目将通过~(13)C和~(15)N核磁共振松弛和运动模型分析来研究未折叠、部分折叠和结构良好的多肽中氨基酸残基的主链和侧链运动。被研究的多肽是三个在水中表现出构象偏好的部分折叠的多肽：(-发夹(12聚体)，(-折叠(20聚体)和螺旋(18聚体)，以及一个锌指肽(31个残基)Sp1f2，它可以在结构良好的天然状态(1：1与锌的络合物)中检测到)，具有(-折叠和螺旋结构)并且处于未折叠状态(不含锌的凋亡肽)。这些多肽的相对较小的尺寸使它们在合成、选择性13C/15N同位素浓缩和实验研究方面都是理想的。该项目与以往的核磁共振动力学研究不同之处在于，它将使用来自所有可用运动矢量(主链和侧链)的自相关和互相关参数以及各种旋转模型和无模型方法来提供关于键旋转限制和关联以及运动几何方面的运动动力学的详细描述。这项研究的意义在于表征未折叠、部分折叠和结构良好的多肽的内部运动。这些信息将更好地了解蛋白质从未折叠到折叠状态转变时发生的变化，对于解决蛋白质折叠问题至关重要。此外，这项研究将增加蛋白质动力学的一般知识，并有助于开发更好的运动模型来分析核磁共振弛豫和结构数据。***

9729539 Mayo Characterizing partially-folded and particularly unfolded states of proteins and peptides has been problematic given their transient nature. 13C/15N NMR relaxation is particularly well suited for investigating these states. This project will study backbone and side-chain motions of amino acid residues in unfolded, partially-folded and well-structured peptides by using 13C and 15N NMR relaxation and motional model analyses. The peptides for study are three partially-folded peptides which show conformational preferences in water: (-hairpin (12mer), (-sheet (20mer) and helix (18mer), and a zinc finger peptide (31 residues) Sp1f2 which can be examined in a well-structured native state (1:1 complex with zinc) having both (-sheet and helical structure and in an "unfolded" state (apopeptide without zinc). The relatively small size of these peptides makes them ideal in terms of synthesis, selective 13C/15N isotopic enrichment, and experimental investigation. This project stands apart from previous NMR dynamics studies in that it will use both auto- and cross-correlation parameters from all available motional vectors (backbone and side-chain) and various rotational models and model free approaches to provide a detailed description of motional dynamics in terms of bond rotational restrictions and correlations and motional geometry. The significance of this research lies in characterizing the internal motions in unfolded, partially-folded and well-structured peptides. This information will provide a better understanding of changes which occur on transition from the unfolded to the folded state of a protein and is crucial to solving the protein folding problem. In addition, this research will increase general knowledge of protein dynamics and contribute to the development of better motional models for analysis of NMR relaxation and structural data. ***