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

考虑到蛋白质和肽的短暂性，表征部分折叠和特别未折叠的状态一直是有问题的。13C/15N核磁共振弛豫特别适合于研究这些状态。该项目将通过13C和15N核磁共振弛豫和运动模型分析，研究未展开、部分折叠和结构良好的肽中氨基酸残基的主链和侧链运动。用于研究的肽是三个部分折叠的肽，它们在水中显示出构象偏好：(-发夹（12mer），(-片（20mer）和螺旋（18mer），以及锌指肽（31个残基）Sp1f2，它可以在结构良好的天然状态（与锌1:1配合）下进行检查，具有（片和螺旋结构）和“展开”状态（不含锌的肽）。这些肽的相对较小的尺寸使它们在合成，选择性13C/15N同位素富集和实验研究方面非常理想。该项目与以前的核磁共振动力学研究不同，它将使用所有可用的运动向量（主链和侧链）的自相关和相互相关参数，以及各种旋转模型和无模型方法，从键旋转限制和相关性以及运动几何角度提供运动动力学的详细描述。本研究的意义在于表征未展开、部分折叠和结构良好的肽的内部运动。这些信息将有助于更好地理解蛋白质从未展开状态转变为折叠状态时发生的变化，对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. ***