INTERNAL MOTIONS IN FOLDED AND UNFOLDED STATES OF GBI

本方案重点研究侧链和主链的运动 用13/C和15/N-核磁共振技术研究链球菌蛋白G-B1结构域的动力学 松弛和旋转模型分析。GB1只有56个氨基酸 残基排列在折叠中，中心α-螺旋与 四股β-折叠。尽管体积很小，但热力学 性质与在较大蛋白质中观察到的性质相似。GB1出借 多肽对13/C/15/N的选择性各向同性富集性 核磁共振弛豫衍生物的合成及实验研究 自体肽和交叉肽的合成及其核磁共振实验研究 关系派生的自体和交叉肽的合成及其实验 利用核磁共振关系导出的自相关谱和互相关谱进行研究 分析所有主链和侧链N-H和C-H运动的密度 向量。本项目的具体目标是：(1)确定内部 所有侧链和主链位置在展开状态下的运动 GB1，以及(3)开发新的方法和运动模型来分析 这些核磁共振弛豫数据。 大多数核磁共振动力学研究都报告了数据，虽然定性地 信息性，仅限于分析自相关参数 [通常来自残基中的单个运动矢量，即主干15/N-H 或13/C/α-H]。这笔赠款 与以前的研究不同的是，它将同时使用自动和 来自所有可用运动矢量(主干)的互相关参数 和侧链)以及各种旋转模型和无模型方法 更详细地描述蛋白质中的运动动力学。 偶极和偶极-CSA互相关谱密度，T/1，T/1p， T/2和至少两个频率的异核NO将被确定。 对于主干运动，13/C/α/H、13/CO和15/NH松弛速率将 被测量，而对于侧链运动，13CH n自动和交叉 相关性将提供独特的运动信息。

This proposal is focused on studying side-chain and backbone motional dynamics in Streptococcal protein G B1 domain by using 13/C and 15/N-NMR relaxation and rotational model analyses. GB1 has only 56 amino acid residues arranged in a fold with a central alpha-helix packed against a four-stranded beta-sheet. Despite its small size, the thermodynamic properties are similar to those observed in larger proteins. GB1 lends itself well to selective 13/C/15/N isotropic enrichment via peptide synthesis and to experimental study using both NMR relaxation-derived auto-and cross-peptide synthesis and to experimental study using both NMR relation-derived auto-and cross-peptide synthesis and to experimental study using both NMR relation-derived auto- and cross-correlation spectral densities for analysis of all backbone and side-chain N-H and C-H motional vectors. The specific aims of this project are: (1) to determine internal motions of all side-chain and backbone positions in unfolded states of GB1, and (3) to develop novel approaches and motional models to analyzes these NMR relaxation data. Most NMR dynamics studies reported to data, while qualitatively informative, are limited to analysis of auto-correlation parameters [usually from a single motional vector in a residue, i.e., backbone 15/N-H or 13/C/alpha-H] derived by using some model free approach. This grant stands apart from previous 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 more detailed description of motional dynamics in a protein. Dipolar and dipolar-CSA cross-correlation spectral densities, T/1, T/1p, T/2 and heteronuclear NOEs at at least two frequencies will be determined. For backbone motions, 13/C/alpha/H, 13/CO and 15/NH relaxation rates will be measured, while for side-chain motions, 13CH n auto- and cross- correlations will provide unique motional information.