四维NOESY光谱的合分解
Sebastian Hiller1, Ilghis Ibraghimov, Gerhard Wagner
1Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 240 Longwood Avenue, Boston Massachusetts 02115, USA.
Journal of the American Chemical Society
|September 10, 2009
概括
这项研究引入了一种新的处理方法,用于四维 (4D) 核重复效应光谱 (NOESY) 光谱,增强生物分子结构的确定. 结合多维分解 (Co-MDD) 方法提高了灵敏度,并允许稀疏的数据采集,这对于大型蛋白质至关重要.
科学领域:
- 结构生物学 结构生物学
- 生物物理学的生物物理.
- 频谱学是一种光谱学.
背景情况:
- 四维 (4D) NOESY光谱提供高分辨率的距离信息,对于确定大型生物分子结构至关重要.
- 传统的4D光谱统一采样是耗时的,限制了实际应用.
- 对于稀少采样的4D NOESY数据需要最佳的处理方法,以充分利用非统一的采样技术.
研究的目的:
- 开发和验证用于稀疏采样的4D NOESY光谱的高效处理方法.
- 提高大型蛋白质结构研究的敏感性和数据质量.
- 为了能够确定复杂的生物分子结构的精确距离约束.
主要方法:
- 从具有质子甲基组 (Ile, Leu, Val) 的无化蛋白质中处理甲基甲基和胺基甲基4D NOESY光谱.
- 结合多维分解 (Co-MDD) 与2D模板光谱相结合的应用.
- 使用较低的稀疏采样水平 (10-15%的完整数据网格).
主要成果:
- 与其他方法相比,Co-MDD方法显著提高了灵敏度,产生了比其他方法多50-100%的交叉峰值.
- 成功应用于一个大蛋白 (283-残留VDAC-1) 具有很长的旋转相关时间 (70 ns).
- 产生了366个NOE,为结构计算提供了139个明确的上限距离约束.
结论:
- 共同MDD是一种有效的处理策略,用于稀疏采样的4D NOESY光谱.
- 这种方法大大提高了生物分子结构确定质量和效率,特别是对于大型蛋白质.
- 这种方法有助于获得复杂蛋白质结构的关键距离约束.
相关概念视频
01:02¹H 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...
01:062D NMR: Homonuclear Correlation Spectroscopy (COSY)
Homonuclear correlation spectroscopy, or COSY, is a 2-dimensional NMR technique that provides information about coupled protons. Typically, the geminal and vicinal coupling are observed. For example, consider the COSY spectrum of ethyl acetate, where its 1D proton NMR spectrum is plotted along the vertical and horizontal axes with their corresponding chemical shift scale. Three spots on the diagonal corresponding to the three peaks in the 1D proton spectrum are called diagonal peaks. The COSY...
01:04¹³C 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...
01:10Interpreting ¹H NMR Signal Splitting: The (n + 1) Rule
In the AX proton spin system, proton A can sense the two spin states of a coupled proton X, resulting in a doublet NMR signal with two peaks of equal (1:1) intensity. When proton A is coupled to two equivalent protons (AX2 spin system), the spin states of each X can be aligned with or against the external field, creating three possible scenarios. This results in a 1:2:1 triplet signal, where the central peak corresponds to the chemical shift of A and is twice as large or intense as the others.
01:12Two-Dimensional (2D) NMR: Overview
The 1D NMR spectrum of large and complex molecules like natural products has complicated splitting patterns and overlapping signals, which can be easily interpreted using 2-dimensional (2D) NMR. Unlike 1D NMR, 2D NMR has two frequency axes that provide the coupling information between the nucleus A and nucleus B in a molecule. The process from which 2D spectra are obtained has four steps.
The first step is the preparation period, during which nucleus A is excited with a radiofrequency pulse.
The first step is the preparation period, during which nucleus A is excited with a radiofrequency pulse.
01:13¹H 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.