Related Experiment Video
Updated: Apr 9, 2026
14:55
Atomic Scale Structural Studies of Macromolecular Assemblies by Solid-state Nuclear Magnetic Resonance Spectroscopy
Published on: September 17, 2017
16.2K
Improved Carbohydrate Structure Generalization Scheme for (1)H and (13)C NMR Simulations
Roman R Kapaev1, Philip V Toukach2
1†Higher Chemical College of the Russian Academy of Sciences, Miusskaya sq. 9, Moscow 125047, Russia.
Analytical Chemistry
|June 19, 2015
Summary
A new Carbohydrate Structure Generalization Scheme enhances NMR spectral simulations for complex carbohydrates. This improved method accurately predicts chemical shifts for glycans, outperforming existing techniques.
Area of Science:
- Carbohydrate Chemistry
- Computational Chemistry
- Spectroscopy
Background:
- Nuclear Magnetic Resonance (NMR) spectroscopy is crucial for characterizing carbohydrate structures.
- Existing methods for simulating NMR spectra of complex carbohydrates have limitations in accuracy and scope.
- Accurate prediction of chemical shifts is essential for elucidating glycan structures.
Purpose of the Study:
- To develop an improved scheme for simulating (13)C and (1)H NMR spectra of oligo- and polysaccharides.
- To enhance the accuracy, performance, and scope of NMR spectral prediction for diverse glycan structures.
- To provide a user-friendly web service for NMR spectral simulation.
Main Methods:
- Development of an improved Carbohydrate Structure Generalization Scheme.
- Integration of (1)H NMR calculations and optimization of the prediction model.
- Implementation within the Glycan-Optimized Dual Empirical Spectrum Simulation (GODESS) web service.
Main Results:
- The new scheme significantly improved the accuracy and performance of chemical shift prediction.
- The method successfully simulated spectra for complex glycans, including those with noncarbohydrate constituents.
- Outperformed existing simulation methods, including database-driven, neural network-based, empirical, and quantum-mechanical approaches.
Conclusions:
- The enhanced Carbohydrate Structure Generalization Scheme offers superior accuracy and broader applicability for NMR spectral simulation.
- The GODESS web service provides a valuable, accessible tool for glycan structure elucidation.
- This advancement facilitates the study of complex carbohydrates and natural glycans.
Related Concept Videos
01:04¹³C NMR: ¹H–¹³C Decoupling
2.1K
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...
2.1K
01:10Carbon-13 (¹³C) NMR: Overview
9.3K
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...
9.3K
01:20¹³C NMR: Distortionless Enhancement by Polarization Transfer (DEPT)
1.9K
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...
1.9K
00:52¹H NMR of Conformationally Flexible Molecules: Temporal Resolution
1.4K
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...
1.4K
01:10Interpreting ¹H NMR Signal Splitting: The (n + 1) Rule
3.2K
In the AX proton spin system, proton A can sense the two spin states of a coupled proton X, resulting in a doublet NMR signal with two peaks of equal (1:1) intensity. When proton A is coupled to two equivalent protons (AX2 spin system), the spin states of each X can be aligned with or against the external field, creating three possible scenarios. This results in a 1:2:1 triplet signal, where the central peak corresponds to the chemical shift of A and is twice as large or intense as the...
3.2K
01:02¹H NMR: Interpreting Distorted and Overlapping Signals
1.8K
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...
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...
1.8K