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甘氨酸C ((alpha) 化学屏蔽在三:通过固态NMR测量和与X射线结构和理论的相关性
Eduard Y Chekmenev1, Ray Z Xu, Mark S Mashuta
1Department of Chemistry, University of Louisville, Louisville, KY 40292, USA.
Journal of the American Chemical Society
|October 3, 2002
概括
本研究测量了碳-13α化学屏蔽参数,用于各种结构中的甘氨酸残留物. 精确的屏蔽参数是使用先进的固态NMR技术获得的,与理论计算有很好的相关性.
科学领域:
- 固态核磁共振 (NMR) 光谱学 固态核磁共振 (NMR) 光谱学
- 生物物理化学 生物物理化学
- 计算化学是一种计算化学.
背景情况:
- 精确确定化学屏蔽参数对于理解和蛋白质结构至关重要.
- 甘氨酸残留物在蛋白质的二次结构中起着重要作用.
- 之前的研究已经探讨了化学变化,但对与二次结构相关的屏蔽参数的详细分析并不常见.
研究的目的:
- 报告 (13)C(alpha) 化学屏蔽参数,用于各种二次结构 (alpha-helix,β-strand,polyglycine II和完全扩展) 中的中央甘氨酸残留物.
- 评估实验不确定性和双极合对屏蔽参数测量的影响.
- 将实验屏蔽参数与理论计算相关联,并将这些趋势扩展到蛋白质结构.
主要方法:
- 使用了固态魔术角度旋转 (MAS) 的NMR光谱法.
- 在自然丰富性和双标记 ([2-(13) C, (15) N] Gly) 三样本上进行了实验.
- (15) 利用N脱来提高光谱分辨率和屏蔽参数的准确性.
主要成果:
- 精确的 (13) C ((alpha) 化学屏蔽参数 (<1 ppm的不确定性) 获得了良好的灵敏度和分辨率.
- 与同位素转移相比, (13) C (((alpha) 屏蔽的异构和不对称性显示出与角的更大变化.
- 实验屏蔽参数与未缩放的初始屏蔽计算有很好的相关性 (rms误差为3ppm).
结论:
- 固态NMR,特别是15N脱,为甘氨酸残留物提供了准确的13C(alpha) 化学屏蔽参数.
- 屏蔽参数和二次结构之间存在明显的趋势.
- 已建立的经验趋势可以扩展到分析蛋白质中的扭转角度.
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