在固态NMR光谱学中使用异质核通过键转移获得的甲基质子接触
Antoine Loquet1, Ségolène Laage, Carole Gardiennet
1Institut de Biologie et Chimie des Protéines, UMR 5086 CNRS/Université de Lyon 1, 7 passage du Vercors, 69367 Lyon, France.
Journal of the American Chemical Society
|July 18, 2008
概括
一个新的固态NMR实验,J-CHHC,通过揭示新的质子-质子接触来增强蛋白质结构的确定. 这种方法提高了结构精度,特别是对于微晶蛋白质.
科学领域:
- 固态核磁共振 (NMR) 光谱学 固态核磁共振 (NMR) 光谱学
- 蛋白质结构的确定蛋白质结构的确定
- 生物物理化学 生物物理化学
背景情况:
- 固态NMR对于研究蛋白质结构至关重要.
- 传统的NMR实验在检测某些结构接触方面存在局限性.
- 准确的结构信息对于理解蛋白质功能至关重要.
研究的目的:
- 为固态NMR引入和验证一种新的2D质子介导碳-碳相关性实验 (J-CHHC).
- 为了证明J-CHHC实验在蛋白质中识别新质子-质子接触的能力.
- 评估J-CHHC衍生限制对蛋白质结构精细化的影响.
主要方法:
- 开发一个二维的质子介导碳-碳相关性实验 (J-CHHC).
- 将J-CHHC实验应用于二元蛋白Crh的微晶样本.
- 利用观察到的质子-质子接触作为3D结构确定距离限制.
主要成果:
- 在J-CHHC实验中,在甲基区域中提供了选择性和敏感的相关性.
- 在Crh蛋白的J-CHHC光谱中观察到总共34个新的质子-质子接触.
- 与X射线结构相比,包括这些新限制措施将骨干RMSD从1.8减少到1.1 Å.
结论:
- J-CHHC实验是蛋白质固态NMR的一个有价值的工具,提供了增强的结构洞察力.
- 这种方法通过提供新的距离限制,显著提高了3D结构确定的准确性.
- J-CHHC技术对于微晶蛋白样品和疏水性核心区域特别有效.
相关概念视频
Proton (¹H) NMR: Chemical Shift
Organic molecules primarily contain carbon and hydrogen atoms. While all the hydrogen isotopes are NMR-active, protium or hydrogen-1 is the most abundant. It has a significant energy separation between its nuclear spin states due to its large gyromagnetic ratio. As per Boltzmann's distribution, an increase in the energy separation implies a greater excess population of nuclei available for excitation, resulting in a strong NMR absorption signal.
Absorption signals of all the protium nuclei in a...
Absorption signals of all the protium nuclei in a...
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.
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 Labile Protons: Temporal Resolution
Protons bonded to heteroatoms such as nitrogen and oxygen exhibit a range of chemical shift values. This is due to the varying degree of hydrogen bonding between the proton and the heteroatom in other molecules. The extent of hydrogen bonding affects the electron density around the proton, thereby giving different chemical shift values for the protons in the proton NMR spectrum.
The –OH proton in alcohols typically appears in the range of δ 2 to 5 ppm but can vary depending on the specific...
The –OH proton in alcohols typically appears in the range of δ 2 to 5 ppm but can vary depending on the specific...
2D NMR: Overview of Heteronuclear Correlation Techniques
Heteronuclear correlation spectroscopy is an analytical technique that investigates the coupling between different types of nuclei, often a proton and an X-nucleus, such as carbon-13 or nitrogen-15. This method is commonly used in nuclear magnetic resonance (NMR) spectroscopy to gain insights into complex chemical compounds' structural and compositional aspects. A typical heteronuclear correlation spectrum displays X-nucleus chemical shifts on one axis and a proton spectrum on the other axis.
¹³C NMR: Distortionless Enhancement by Polarization Transfer (DEPT)
When proton-coupled carbon-13 spectra are simplified by a broadband proton decoupling technique, structural information about the coupled protons is lost. Distortionless enhancement by polarization transfer (DEPT) is a technique that provides information on the number of hydrogens attached to each carbon in a molecule. While the DEPT experiment utilizes complex pulse sequences, the pulse delay and flip angle are specifically manipulated. The resulting signals have different phases depending on...


