Related Experiment Video
Updated: Jun 14, 2026
14:55
Atomic Scale Structural Studies of Macromolecular Assemblies by Solid-state Nuclear Magnetic Resonance Spectroscopy
Published on: September 17, 2017
A non-uniformly sampled 4D HCC(CO)NH-TOCSY experiment processed using maximum entropy for rapid protein sidechain
Mehdi Mobli1, Alan S Stern, Wolfgang Bermel
1Institute for Molecular Bioscience, The University of Queensland, St. Lucia, 4072 QLD, Australia. m.mobli@uq.edu.au
Journal of Magnetic Resonance (San Diego, Calif. : 1997)
|March 20, 2010
Summary
Nuclear Magnetic Resonance (NMR) sidechain resonance assignment is challenging. A new 4D NMR experiment simplifies this, offering time efficiency and improved resolution for protein structural studies.
Area of Science:
- Biochemistry
- Structural Biology
- Analytical Chemistry
Background:
- Sidechain resonance assignment in protein Nuclear Magnetic Resonance (NMR) is a critical yet challenging step in structural studies.
- Conventional methods often require multiple, time-consuming 3D NMR experiments to resolve ambiguities and establish connectivities.
Purpose of the Study:
- To introduce a novel, single 4D NMR experiment to replace lengthy 3D experiments for protein sidechain resonance assignment.
- To demonstrate the time-efficiency and enhanced resolution of this new 4D approach.
Main Methods:
- Development and application of a single 4D NMR experiment.
- Utilizing non-uniform sampling in three indirect time dimensions.
- Employing maximum entropy reconstruction for data processing.
Main Results:
- The 4D experiment successfully replaces multiple 3D experiments, offering significant time savings.
- Achieved excellent spectral resolution and captured unique carbon-proton connectivity information.
- Demonstrated the practicality of the method through non-uniform sampling and maximum entropy reconstruction.
Conclusions:
- This 4D NMR method significantly streamlines protein sidechain resonance assignment.
- The approach is expected to accelerate automated resonance assignment protocols.
- This technique holds great promise for increasing throughput in structural genomics initiatives using NMR.
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...
01:062D NMR: Homonuclear Correlation Spectroscopy (COSY)
Homonuclear correlation spectroscopy, or COSY, is a 2-dimensional NMR technique that provides information about coupled protons. Typically, the geminal and vicinal coupling are observed. For example, consider the COSY spectrum of ethyl acetate, where its 1D proton NMR spectrum is plotted along the vertical and horizontal axes with their corresponding chemical shift scale. Three spots on the diagonal corresponding to the three peaks in the 1D proton spectrum are called diagonal peaks. The COSY...
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...
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...
01:182D 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.
01:06Nuclear Overhauser Enhancement (NOE)
Irradiation of a spin-active nucleus causes an increase or decrease in the signal intensity of neighboring nuclei that are not necessarily chemically bonded or involved in J-coupling. This phenomenon, called the nuclear Overhauser enhancement (NOE), results from through-space interactions between the nuclear spins. The NOE effect decreases with increasing internuclear distance and is generally not observed beyond 4 angstroms. In NOE, dipole-dipole interactions between neighboring spin-active...