15N-1H标量合扰动:一个额外的探测器用于测量由连接体结合引起的结构变化
Junhe Ma1, James M Gruschus, Nico Tjandra
1Laboratory of Molecular Biophysics, National Heart, Lung, and Blood Institute, National Institutes of Health, 50 South Drive, Bethesda, Maryland 20892, USA.
Journal of the American Chemical Society
|July 8, 2009
概括
胺标尺合扰动映射揭示了离结位附近和远处的结构变化. 这种技术补充了化学转移映射,提供了对生物分子相互作用和全效应的见解.
科学领域:
- 生物分子核磁共振 (NMR) 光谱学
- 结构生物学 结构生物学
- 蛋白质 - 连接体相互作用
背景情况:
- 骨干胺基的化学转移扰动 (CSP) 映射是生物分子NMR中的标准技术.
- CSP提供了关于相互作用接口,配体结合和修饰位点的残留特异性数据,即使对于具有挑战性的生物分子样本也是如此.
- 胺 (15) N-(1) H 的标量合常量也可以在联结时发生变化.
研究的目的:
- 调查胺标量合恒定扰动的实用性,作为CSP的补充技术.
- 评估从标量合扰动中获得的关于结构变化的信息,包括全效应.
- 评估这种方法在理解谷氨酸结合蛋白 (GlnBP) 相互作用方面的应用.
主要方法:
- 核磁共振 (NMR) 光谱法被用于测量化学转移扰动和胺 (15) N-(1) H标尺合常量.
- 这项研究的重点是氨酸结合蛋白 (GlnBP) 和其对联体结合的反应.
- 分析涉及比较标量合常数变化与化学转移扰动.
主要成果:
- 观察到胺 (15) N-(1) H标尺合常数在连接物与 GlnBP 结合时发生显著变化,在结合部位附近发生大的干扰 (> 1 Hz).
- 此外,在距离直接连接体结合部位远的地方也检测到了标尺合扰乱,这表明了全效应.
- 这些合常数扰动与实质性的结构重组相关,特别是在骨干结模式中.
结论:
- 胺标尺合扰动映射是生物分子核磁共振中的化学转移扰动映射的宝贵补充.
- 这种技术为本地和远程,全性结构动态提供了额外的见解.
- 它增强了对生物分子相互作用和结构变化的理解.
相关概念视频
01:27¹H NMR: Long-Range Coupling
The coupling interactions of nuclei across four or more bonds are usually weak, with J values less than 1 Hz. While these are usually not observed in spectra, the presence of multiple bonds along the coupling pathway can result in observable long-range coupling.
In alkenes, spin information is communicated via σ–π overlap, as seen in allylic (four-bond) and homoallylic (five-bond) couplings. These coupling interactions are stronger when the σ bond is parallel to the alkene π orbitals.
In alkenes, spin information is communicated via σ–π overlap, as seen in allylic (four-bond) and homoallylic (five-bond) couplings. These coupling interactions are stronger when the σ bond is parallel to the alkene π orbitals.
01:17Spin–Spin Coupling: One-Bond Coupling
Coupling interactions are strongest between NMR-active nuclei bonded to each other, where spin information can be transmitted directly through the pair of bonding electrons. While nuclei polarize their electrons to the opposite spins, the bonding electron pair has opposite spins. Configurations with antiparallel nuclear spins are expected to be lower in energy. When coupling makes antiparallel states more favorable, J is considered to have a positive value. The one-bond coupling constant, 1J,...
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...
01:08Spin–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...
01:20¹³C 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...
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.