205Tl NMR方法用于表征与核酸结合的单价离子
Michelle L Gill1, Scott A Strobel, J Patrick Loria
1Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520, USA.
Journal of the American Chemical Society
|November 25, 2005
概括
(Tl+) 离子作为 (K+) 替代物,稳定了G-四重复的DNA结构. 这项研究证实了Tl + 与K + 是同型的,并揭示了用于结构分析的新型Tl + - 质子合.
科学领域:
- 生物化学 生物化学
- 结构生物学 结构生物学
- 生物有机化学 生物有机化学
背景情况:
- 单价离子对许多生物过程至关重要.
- 富含关氨酸的序列,如d(G4T4G4) 形成G-四重复结构,d(G4T4G4) 2,需要这些.
- (Tl+) 可以替代 (K+) 稳定这些结构.
研究的目的:
- 为了确定Tl+结合的d(G4T4G4)2 G四重复的溶液结构.
- 为了比较Tl + 绑定结构与K + 绑定形式,以评估等态行为.
- 调查Tl +作为G-四重复结构确定探针的潜力.
主要方法:
- 核磁共振 (NMR) 光谱法以确定溶液结构.
- 用RMSD分析计算10个最低能量的结构.
- 1H-205Tl旋转回声差异实验用于检测合.
主要成果:
- 确定了Tl+-d(G4T4G4)2的溶液结构,与K+形式具有很高的结构相似性 (RMSD为0.76 +/- 0.16 Å).
- 这证实了Tl+和K+在这个G-quadruplex中是同型的.
- 报告了在生物系统中首次观察到1H-205Tl标量合的情况.
结论:
- Tl+是d(G4T4G4) 2G四复合体中K+的有效同型替代品.
- 观察到的Tl+ - 质子合为G-四重复结构的确定提供了新的约束.
- 这种NMR技术为研究生物系统中的离子相互作用提供了一种新的方法.
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.
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...
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Other Nuclides: 31P, 19F, 15N NMR
Many organic, inorganic, and biological molecules contain spin-half nuclei such as nitrogen-15, fluorine-19, and phosphorus-31. As a result, NMR studies of these nuclei have found extensive applications in chemical and biological research.
While fluorine-19 and phosphorous-31 have high natural abundances (100%) and positive gyromagnetic ratios, nitrogen-15 has a low natural abundance and a negative gyromagnetic ratio. However, nitrogen-15 is still preferred over nitrogen-14 (which has a high...
While fluorine-19 and phosphorous-31 have high natural abundances (100%) and positive gyromagnetic ratios, nitrogen-15 has a low natural abundance and a negative gyromagnetic ratio. However, nitrogen-15 is still preferred over nitrogen-14 (which has a high...
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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...
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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.


