Related Experiment Video
Updated: Jul 15, 2026
13:16
Pure Shift Nuclear Magnetic Resonance: a New Tool for Plant Metabolomics
Published on: July 31, 2021
NMR-based fluxomics: quantitative 2D NMR methods for isotopomers analysis
Stéphane Massou1, Cécile Nicolas, Fabien Letisse
1Laboratoire Biotechnologie - Bioprocédés, UMR INSA/CNRS 5504 INRA 792, LBB/INSA, 135 Avenue de Rangueil, 31077 Toulouse Cedex 4, France.
Phytochemistry
|May 1, 2007
Summary
Two-dimensional Total Correlation Spectroscopy (2D-TOCSY) NMR experiments accurately measure carbon-13 (¹³C) enrichments in complex metabolic mixtures. This method, when enhanced with zero-quantum filters, improves the analysis of dynamic metabolic systems.
Area of Science:
- Metabolomics
- Nuclear Magnetic Resonance (NMR) Spectroscopy
- Biochemistry
Background:
- Accurate quantification of isotopologue distributions is crucial for understanding metabolic pathways.
- Traditional Nuclear Magnetic Resonance (NMR) methods face challenges in precisely measuring carbon-13 (¹³C) enrichments in complex biological samples.
Purpose of the Study:
- To evaluate the reliability of 2D-COSY and 2D-TOCSY NMR experiments for quantifying ¹³C-enrichments.
- To determine the suitability of these NMR techniques for analyzing ¹³C-labeled metabolites in complex mixtures.
Main Methods:
- Theoretical analysis of 2D-COSY and 2D-TOCSY experiments.
- Experimental validation using ¹³C-labeled metabolites.
- Implementation of efficient zero-quantum filters during the mixing period of 2D-TOCSY experiments.
Main Results:
- 2D-COSY experiments were found to be unreliable for accurate ¹³C-enrichment measurements.
- 2D-TOCSY experiments, with the application of efficient zero-quantum filters, provided accurate ¹³C-enrichment quantification.
- The optimized 2D-TOCSY method demonstrated suitability for complex metabolic mixtures.
Conclusions:
- Optimized 2D-TOCSY NMR is a reliable method for measuring ¹³C-enrichments in complex ¹³C-labeled metabolic mixtures.
- This technique expands the utility of NMR in metabolic flux analysis and the study of dynamic metabolic systems.
Related Concept Videos
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...
01:12Two-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.
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...
01:182D 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.
01:062D 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...
01:15¹H NMR of Conformationally Flexible Molecules: Variable-Temperature NMR
The axial and equatorial protons in cyclohexane can be distinguished by performing a variable-temperature NMR experiment. In this process, except for one proton, the remaining eleven protons are replaced by deuterium. The deuterium substitution avoids the possible peak splitting caused by the spin-spin coupling between the adjacent protons. The remaining proton flips between the axial and equatorial positions.