PEPTIDE STRUCTURE & DYNAMICS

了解肽的结构和动力学是非常有趣的 在化学和生物学上。 EPR方法已被用于排序 双标记肽中侧链之间的距离， 从而 揭示了局部折叠的几何形状。 近年来， 标记的肽已被证明是一种很好的探针 位置相关动力学 尽管这些EPR实验 大大增加了我们对肽运动的理解，许多 重要的细节仍未解决。 特别是，常规9 GHz EPR谱对各向异性不特别敏感， 自旋标签运动。 本地标签的全面表征 为了澄清对《公约》的解释， 位置相关动力学，并帮助确定 双标记实验中的距离。 高频EPR已被 被证明比9 GHz光谱对运动更敏感 在短的相关时间内的各向异性。 我们获得了高 基于丙氨酸的3 K- 11螺旋肽的频率EPR谱， 温度为275-305 K。如下所示的3 K-II螺旋肽， 在半胱氨酸处用甲硫基磺酸盐（MTSSL）自旋标记 label. Ac-AAAAAKAAAAAKCAAAKA-NH_2高频EPR谱显示 对运动各向异性的灵敏度比低频谱高 但仍然可以根据以下公式进行简单的线形分析 动态线窄化理论 模拟实验 使用不同自旋各向异性运动模型的光谱 连接到肽骨架的标签链正在进行中。

Understanding peptide structure and dynamics is of great interest in chemistry and biology. EPR methods have been used to rank distances between side chains in doubly labeled peptides, thereby revealing local folding geometry. Recently, EPR of site-specific spin labeled peptides has been shown to be an excellent probe of-position-dependent dynamics. Although these EPR experiments have added considerably to our understanding of peptide motions, many important details remain unresolved. In particular, conventional 9 GHz EPR spectra are not particularly sensitive to the anisotropy of the spin label motion. Thorough characterization of the local label motion is necessary in order to clarify the interpretation of the position-dependent dynamics and to aid in the determination of distances in double label experiments. High frequency EPR has been demonstrated to be more sensitive than 9 GHz spectra to motional anisotropy at short correlation times. We have obtained high frequency EPR spectra of the alanine based 3K- 11 helical peptide at temperatures from 275-305 K. The 3K- I I helical peptide, shown below, is labeled at the cysteine with a methanethiosulfonate (MTSSL) spin label. Ac-AAAAKAAAAKCAAAKA-NH2 The high frequency EPR spectra exhibit greater sensitivity to motional anisotropy than low frequency spectra but remain amenable to simple line shape analysis according to motional line narrowing theory. Simulations of the experimental spectra using different models for the anisotropic motion of the spin label chain attached to the peptide backbone are in progress.