Related Experiment Video
Updated: Jul 17, 2026
14:55
Atomic Scale Structural Studies of Macromolecular Assemblies by Solid-state Nuclear Magnetic Resonance Spectroscopy
Published on: September 17, 2017
Residue-specific 13C' CSA tensor principal components for ubiquitin: correlation between tensor components and
Robert A Burton1, 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
|February 1, 2007
Summary
Nuclear magnetic resonance (NMR) reveals how protein structure influences 13C chemical shift anisotropy (CSA) tensors. This study shows CSA tensors are sensitive to hydrogen-bond length, offering new insights into protein dynamics.
Area of Science:
- Biophysics
- Structural Biology
- Nuclear Magnetic Resonance (NMR) Spectroscopy
Background:
- Understanding protein structure and dynamics is crucial in molecular biology.
- Nuclear magnetic resonance (NMR) spectroscopy is a powerful tool for studying protein structure.
- Chemical Shift Anisotropy (CSA) provides valuable information about the local electronic environment of nuclei in proteins.
Purpose of the Study:
- To determine residue-specific 13C' CSA tensor principal components and orientation in ubiquitin using solution NMR.
- To investigate the influence of protein environment and hydrogen bonding on 13C' CSA tensors.
- To evaluate the potential of 13C' CSA for probing structural variables in proteins.
Main Methods:
- Solution NMR spectroscopy was used to study uniformly labeled ubiquitin.
- Proteins were partially aligned in four different media to obtain residual dipolar couplings.
- Spurious chemical shift deviations due to solvent effects were corrected using linear regression analysis.
Main Results:
- Residue-specific 13C' CSA tensor principal components and orientation were determined.
- 13C' CSA tensors were found to be sensitive to hydrogen-bond length but not hydrogen-bond angle.
- Weak correlations between CSA tensors and structural factors suggest confounding influences.
Conclusions:
- Solution NMR data provide a comprehensive sampling of 13C' CSA for various amino acid types.
- The study demonstrates the utility of 13C' CSA in evaluating structural variables in proteins.
- Further research with more extensive data is needed to fully exploit the potential of 13C' CSA analysis.
Related Concept Videos
01:192D NMR: Heteronuclear Single-Quantum Correlation Spectroscopy (HSQC)
Heteronuclear single-quantum correlation spectroscopy (HSQC) is a 2D NMR technique that reveals one-bond correlations between hydrogen and a heteronucleus. The HSQC experiment is similar to the heteronuclear correlation experiment (HETCOR) but is more sensitive. In the HSQC spectrum, the proton chemical shift is plotted on the horizontal F2 axis, while the 13C chemical shift is plotted on the vertical F1 axis. The corresponding proton and 13C spectra are also shown. The HSQC contour plot does...
01:04¹³C 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...
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...
01:10Carbon-13 (¹³C) NMR: Overview
Carbon-13 is a naturally occurring NMR-active isotope of carbon with a low natural abundance of 1.1%. In contrast, carbon-12 is the most abundant isotope of carbon with zero nuclear spin. Therefore, it is NMR inactive. The gyromagnetic ratio of carbon-13 is smaller than that of protons. As a result, carbon-13 resonance is about 6000 times weaker than proton resonance. For a given magnetic field strength, the resonance frequency of carbon-13 is about one-fourth of the resonance frequency for...
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.
01:23IR Spectrum Peak Broadening: Hydrogen Bonding
The vibrational frequency of a bond is directly proportional to its bond strength. As a result, stronger bonds vibrate at higher frequencies, while weaker bonds vibrate at lower frequencies. The stretching vibration of the strong O–H bond in alcohols and phenols (very dilute solution or gas phase) appears as a sharp peak at 3600–3650 cm−1.
However, the extent of hydrogen bonding influences the observed stretching frequency and band broadening. Intermolecular or intramolecular hydrogen bonding...
However, the extent of hydrogen bonding influences the observed stretching frequency and band broadening. Intermolecular or intramolecular hydrogen bonding...