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使用分子动力学模拟来解释β-的NMR数据
Daniel Trzesniak1, Alice Glättli, Bernhard Jaun
1Laboratory of Physical Chemistry, Swiss Federal Institute of Technology Zürich, ETH-Hönggerberg, CH-8093 Zürich, Switzerland.
Journal of the American Chemical Society
|October 13, 2005
概括
分子动力学 (MD) 模拟提供了与实验核磁共振 (NMR) 数据相容的构造组合. 这种方法解决了蛋白质和结构确定中的不一致性,揭示了微妙的形状差异.
科学领域:
- 结构生物学 结构生物学
- 计算化学计算化学
- 生物物理学的生物物理.
背景情况:
- 核磁共振 (NMR) 光谱对于确定溶液中的蛋白质和结构至关重要.
- 在使用传统的NMR数据 (NOE, (3) J值) 进行结构确定时,聚类的 conformational异质性可能会导致不一致.
- 基于限制的方法可能无法准确地表示具有多重构造的系统.
研究的目的:
- 证明不受约束的分子动力学 (MD) 模拟可以生成与实验性NMR数据一致的构造组合.
- 通过在模拟的形状集的背景下解释NMR数据来解决不一致的问题.
- 为了研究β-的受保护和不受保护的形式之间的形状差异.
主要方法:
- 在两个温度下在甲醇中进行了四个100ns无约束的MD模拟,对甲醇中的9个残留β-进行了模拟.
- 从MD模拟中生成的形状合集.
- 计算了之间的距离,以预测核过量效应 (NOE),并将其与实验数据进行比较.
主要成果:
- MD模拟产生了与实验NMR数据大致相容的构造组合,解决了不一致性.
- 贝塔主要采用12/10螺旋结构,但模拟显示在未受保护的形式中存在3(14)() 螺旋结构.
- 3(14)() -螺旋结构的存在与满足特定的实验NOE相关.
- MD组合突出了受保护和不受保护的β-形式之间的小,特定的形状差异.
结论:
- 无约束的MD模拟是一种强大的工具,用于生成精确的溶液中的和蛋白质的构造组合.
- 模拟MD促进实验NMR数据的详细和一致的解释,特别是对形状异质的系统.
- 这种方法成功地通过考虑多重构造来识别和解释NMR数据中的差异.
相关概念视频
¹H NMR: Complex Splitting
A proton M that is coupled to a proton X results in doublet signals for M. However, NMR-active nuclei can be simultaneously coupled to more than one nonequivalent nucleus. When M is coupled to a second proton A, such as in styrene oxide, each peak in the doublet is split into another doublet.
Splitting diagrams or splitting tree diagrams are routinely used to depict such complex couplings. While drawing splitting diagrams, the splitting with the larger coupling constant is usually applied first.
Splitting diagrams or splitting tree diagrams are routinely used to depict such complex couplings. While drawing splitting diagrams, the splitting with the larger coupling constant is usually applied first.
¹H NMR: Interpreting Distorted and Overlapping Signals
Spin systems where the difference in chemical shifts of the coupled nuclei is greater than ten times J are called first-order spin systems. These nuclei are weakly coupled, and their chemical shifts and coupling constant can generally be estimated from the well-separated signals in the spectrum.
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are slanted or...
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are slanted or...
NMR Spectroscopy: Spin–Spin Coupling
The spin state of an NMR-active nucleus can have a slight effect on its immediate electronic environment. This effect propagates through the intervening bonds and affects the electronic environments of NMR-active nuclei up to three bonds away; occasionally, even farther. This phenomenon is called spin–spin coupling or J-coupling. Coupling interactions are mutual and result in small changes in the absorption frequencies of both nuclei involved. While nuclei of the same element are involved in...
Spin–Spin Coupling Constant: Overview
In bromoethane, the three methyl protons are coupled to the two methylene protons that are three bonds away. In accordance with the n+1 rule, the signal from the methyl protons is split into three peaks with 1:2:1 relative intensities. The methylene protons appear as a quartet, with the relative intensities of 1:3:3:1.
Qualitatively, any spin plus-half nucleus polarizes the spins of its electrons to the minus-half state. Consequently, the paired electron in the hydrogen–carbon bond must have a...
Qualitatively, any spin plus-half nucleus polarizes the spins of its electrons to the minus-half state. Consequently, the paired electron in the hydrogen–carbon bond must have a...
¹H NMR of Conformationally Flexible Molecules: Variable-Temperature NMR
The axial and equatorial protons in cyclohexane can be distinguished by performing a variable-temperature NMR experiment. In this process, except for one proton, the remaining eleven protons are replaced by deuterium. The deuterium substitution avoids the possible peak splitting caused by the spin-spin coupling between the adjacent protons. The remaining proton flips between the axial and equatorial positions.
¹³C NMR: ¹H–¹³C Decoupling
The probability of having two carbon-13 atoms next to each other is negligible because of the low natural abundance of carbon-13. Consequently, peak splitting due to carbon-carbon spin-spin coupling is not observed in spectra. However, protons up to three sigma bonds away split the carbon signal according to the n+1 rule, resulting in complicated spectra.
A broadband decoupling technique is used to simplify these complex, sometimes overlapping, signals. Broadband decoupling relies on a...
A broadband decoupling technique is used to simplify these complex, sometimes overlapping, signals. Broadband decoupling relies on a...

