在蛋白质混合物上使用2D魔力角旋转NMR探测分子接口,这些蛋白质混合物具有不同的统一标签
Manuel Etzkorn1, Anja Böckmann, Adam Lange
1Max-Planck-Institute for Biophysical Chemistry, Department of NMR-based Structural Biology, Am Fassberg 11, 37077 Göttingen, Germany.
Journal of the American Chemical Society
|November 13, 2004
概括
这项研究引入了一种新的核磁共振 (NMR) 方法,用于研究分子接口. 该技术分析了异质标记的分子混合物,揭示了微结晶状态下的蛋白质-蛋白质相互作用.
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 (NMR) 光谱学 核磁共振 (NMR) 光谱学
背景情况:
- 研究分子接口对于理解生物过程至关重要.
- 在固态条件下直接观察这些接口存在重大挑战.
- 现有的NMR方法在解决特定接口相互作用方面可能存在局限性.
研究的目的:
- 为直接调查分子界面制定一个一般的核磁共振 (NMR) 策略.
- 为了使分子相互作用在微晶状态的研究.
- 为了证明这种方法对分析蛋白质结构的有用性.
主要方法:
- 一种新的NMR策略,采用均但异质的标记分子混合物 (旋转物种X:Y).
- 使用特定的核旋转转移进行光谱分析,包括 (15) N - 13 C (NC), (1) H - 15 N - 13 C (NHC) 和 (1) H - 15 N - 1 H - 13 C (NHHC) 转移.
- 应用到标记为 ((13) C: ((15) N) 的85氨基酸蛋白Crh.的二元形式.
主要成果:
- 对标记样本的NC,NHC和NHHC转移的证明 ((15) N: ((13) C).
- 成功地应用了NHHC方法来研究Crh蛋白的二次形式.
- 在蛋白质的微晶状态内识别各种单体-单体相互作用.
结论:
- 开发的NMR策略提供了一种直接的方法,用于研究在神奇的角度旋转条件下分子接口.
- 这种方法对于在固态中描述蛋白质与蛋白质相互作用是有效的.
- 这种技术为在微晶环境中蛋白质的结构动态提供了新的见解.
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.
Two-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.
Interpreting 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.
¹H NMR: Pople Notation
The Pople nomenclature system classifies spin systems based on the difference between their chemical shifts. Coupled spins are denoted by capital letters with subscripts indicating the number of equivalent nuclei. When the coupled nuclei have well-separated chemical shifts, they are assigned letters that are far apart in the alphabet, such as A and X. When the difference in chemical shifts is small, coupled nuclei are named using adjacent letters of the alphabet (AB, MN, or XY).
A proton...
A proton...
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...
2D NMR: Overview of Homonuclear Correlation Techniques
Homonuclear correlation spectroscopy (COSY) is a powerful technique used in Nuclear Magnetic Resonance (NMR) spectroscopy to study the correlations between nuclei of the same type within a molecule. It provides information about scalar couplings between adjacent nuclei, which helps determine connectivity and structural information. There are several COSY variants, each with its unique strengths and experimental parameters.
COSY90 is the standard two-dimensional (2D) COSY experiment that...
COSY90 is the standard two-dimensional (2D) COSY experiment that...


