蛋白质形状异质性对NMR线形在冷温度下的贡献
Xu Yi1, Keith J Fritzsching1, Rivkah Rogawski1
1Department of Chemistry, Columbia University, New York, NY 1002.
概括
低温核磁共振 (NMR) 显示了蛋白质的结构异质性. 脊柱扭转角度的不均分布有助于冷蛋白样本的光谱扩展,影响NMR分析.
科学领域:
- 生物物理学的生物物理.
- 结构生物学 结构生物学
- 核磁共振光谱学 核磁共振光谱学
背景情况:
- 低温NMR提供了更高的灵敏度和对不稳定的生物分子的分析.
- 在冷蛋白样本中的光谱扩展是一个重要的实验挑战.
- 假设形态异质性是由于结的平衡导致这种扩展的原因.
研究的目的:
- 使用核磁共振 (NMR) 调查冷蛋白质的构造异质性.
- 在低温 (105K) 条件下测量大肠杆菌*二叶酸还原酶 (DHFR) 中的脊柱扭转角度 (Ψ).
- 探索构造分布对光谱线扩展的贡献.
主要方法:
- 核磁共振 (NMR) NCCN Ψ实验的修改,以将Ni+1化学转移与 Ψi相关联.
- 在DHFR中选择性N和C同位素丰富异黄素残留物.
- 对C'-N相关性光谱进行分析,以识别不同的构造状态.
主要成果:
- 基于化学转移分散,在DHFR中检测出I60-I61胺的三个不同的构造盆地.
- 这些盆地的脊柱扭转角度 (Ψ) 的确定:114 ± 7°,150 ± 8°和164 ± 16°.
- 测量角度与X射线晶体结构 (118°) 和以前报告的值的比较.
结论:
- 这项研究支持这样一个假设,即形状异质性在低温NMR中有助于光谱扩大.
- 蛋白质骨干扭转角度的不均分布被确定为一个关键因素.
- 这些发现有助于理解和应用低温核磁共振来分析蛋白质动态.
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