在TROSY NMR光谱学中长度 (1) H放松优化
Konstantin Pervushin1, Beat Vögeli, Alexander Eletsky
1Laboratorium für Physikalische Chemie, Eidgenössische Technische Hochschule Hönggerberg, CH-8092 Zürich, Switzerland. kopeko@phys.chem.ethz.ch
Journal of the American Chemical Society
|October 24, 2002
概括
这项研究引入了一种新的方法,通过减少质子放松时间来提高高场核磁共振 (NMR) 实验的灵敏度. 这种技术提高了蛋白质NMR的信号噪声比率,这对于结构分析至关重要.
科学领域:
- 生物物理化学 生物物理化学
- 结构生物学 结构生物学
- 核磁共振光谱学 核磁共振光谱学
背景情况:
- 高极化磁场对于先进的多维NMR实验至关重要.
- 在NMR中提高灵敏度对于分析蛋白质等复杂生物分子至关重要.
- 质子放松时间显著影响NMR实验的灵敏度.
研究的目的:
- 描述一种通过减少纵向质子放松时间来增强NMR灵敏度的一般方法.
- 为了均地增强1HN旋转的纵向放松,使用"热浴"1H旋转.
- 为了提高蛋白质分析的多脉冲NMR实验的灵敏度.
主要方法:
- 使用两个大池的"热浴"1H旋转 (在C-H和O-H键上) 来加速1HN旋转放松.
- 在2D [15N,1H]-LTROSY,2D [15N,1H]-LHSQC和3D LTROSY-HNCA实验中实施纵向放松优化.
- 将该方法应用于标记的13C,15N和完全质子化或部分化蛋白质.
主要成果:
- 在经过测试的NMR实验中,在600 MHz的单位时间内,最大信号噪声比增加了2-2.5倍.
- 证明1HN旋转的纵向放松的均增强.
- 预测了在900MHz的1HN纵向放松时间下降的潜在一个数量级下降.
结论:
- 开发的方法有效地提高了在高磁场的多维NMR实验中的灵敏度.
- 这种技术为蛋白质NMR研究提供了显著的改进,特别是在非常高的场强度下.
- 该方法是使用NMR提高蛋白质结构确定效率和范围的宝贵工具.
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...
00:52¹H NMR of Conformationally Flexible Molecules: Temporal Resolution
At room temperature, the chair conformer of cyclohexane undergoes rapid ring flipping between two equivalent chair conformers at a rate of approximately 105 times per second. These two chair conformers are in equilibrium. The rapid ring flipping results in the interconversion of the axial proton to an equatorial proton and an equatorial to the axial proton. Such interconversions are too rapid and cannot be detected on the NMR timescale. Hence, the NMR spectrometer cannot distinguish between the...
01:14NMR Spectrometers: Resolution and Error Correction
When magnetic nuclei in a sample achieve resonance and undergo relaxation, the signal detected in NMR is an approximately exponential free induction decay. Fourier transform of an exponential decay yields a Lorentzian peak in the frequency domain. Lorentzian peaks in an NMR spectrum are defined by their amplitude, full width at half maximum, and position, where the peak width is governed by the spin-spin relaxation time alone. In real experiments, however, the applied magnetic field is rendered...
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.
01:162D 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...
01:182D 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.