Overlap of NMR signals is the major cause of difficulties associated with NMR structure elucidation of molecules contained in complex mixtures. A 2D homonuclear correlation spectroscopy in particular suffers from low dispersion of 1H chemical shifts; larger dispersion of 13C chemical shifts is often used to reduce this overlap, while still providing the protonā??proton correlation information e.g. in the form of a 2D 1H, 13C HSQC-TOCSY experiment. For this methodology to work, 13C chemical shift must be resolved. In case of 13C chemical shifts overlap, 1H chemical shifts can be used to achieve the desired resolution. The proposed (3, 2)D 1H, 13C BIRDr,X-HSQC-TOCSY experiment achieves this while preserving singlet character of cross peaks in the F1 dimension. The required high-resolution in the 13C dimension is thus retained, while the cross peak overlap occurring in a regular HSQC-TOCSY experiment is eliminated. The method is illustrated on the analysis of a complex carbohydrate mixture obtained by depolymerisation of a fucosylated chondroitin sulfate isolated from the body wall of the sea cucumber Holothuria forskali.
[NMR paper] Absolute Minimal Sampling of Homonuclear 2D NMR TOCSY Spectra for High-Throughput Applications of Complex Mixtures
Absolute Minimal Sampling of Homonuclear 2D NMR TOCSY Spectra for High-Throughput Applications of Complex Mixtures
Modern applications of 2D NMR spectroscopy to diagnostic screening, metabolomics, quality control, and other high-throughput applications are often limited by the time-consuming sampling requirements along the indirect time domain t1. 2D total correlation spectroscopy (TOCSY) provides unique spin connectivity information for the analysis of a large number of compounds in complex mixtures, but standard methods typically require >100 t1 increments for an accurate spectral...
nmrlearner
Journal club
0
06-13-2017 09:46 PM
Maximal clique method for the automated analysis of NMR TOCSY spectra of complex mixtures
Maximal clique method for the automated analysis of NMR TOCSY spectra of complex mixtures
Abstract
Characterization of the chemical components of complex mixtures in solution is important in many areas of biochemistry and chemical biology, including metabolomics. The use of 2D NMR total correlation spectroscopy (TOCSY) experiments has proven very useful for the identification of known metabolites as well as for the characterization of metabolites that are unknown by taking advantage of the good resolution and high sensitivity of this homonuclear...
nmrlearner
Journal club
0
06-01-2017 03:02 PM
[NMR paper] Application of comprehensive NMR-based analysis strategy in annotation, isolation and structure elucidation of low molecular weight metabolites of Ricinus communis seeds.
Application of comprehensive NMR-based analysis strategy in annotation, isolation and structure elucidation of low molecular weight metabolites of Ricinus communis seeds.
Related Articles Application of comprehensive NMR-based analysis strategy in annotation, isolation and structure elucidation of low molecular weight metabolites of Ricinus communis seeds.
Phytochem Anal. 2015 Oct 14;
Authors: Vu?kovi? I, Rapinoja ML, Vaismaa M, Vanninen P, Koskela H
Abstract
INTRODUCTION: Powder-like extract of Ricinus communis seeds contain a...
[NMR images] Side-chain assignment with a 15N-TOCSY-HSQC spectrum
http://www.protein-nmr.org.uk/pictures/assign_theory/assign_15ntocsy_principle.png
8/04/2014 7:46:05 AM GMT
Side-chain assignment with a 15N-TOCSY-HSQC spectrum
More...
nmrlearner
NMR pictures
0
04-08-2014 07:45 AM
[NMR paper] Recent advances in computational predictions of NMR parameters for the structure elucidation of carbohydrates: methods and limitations.
Recent advances in computational predictions of NMR parameters for the structure elucidation of carbohydrates: methods and limitations.
Related Articles Recent advances in computational predictions of NMR parameters for the structure elucidation of carbohydrates: methods and limitations.
Chem Soc Rev. 2013 Jul 25;
Authors: Toukach FV, Ananikov VP
Abstract
All living systems are comprised of four fundamental classes of macromolecules - nucleic acids, proteins, lipids, and carbohydrates (glycans). Glycans play a unique role of joining three...
nmrlearner
Journal club
0
07-28-2013 07:46 PM
[Question from NMRWiki Q&A forum] 3d Tocsy-hsqc mgnetization transfer problem
3d Tocsy-hsqc mgnetization transfer problem
Dear All,I acquired a 3d tocsy-hsqc edited on Bruker machine of small protein in micelles with a mixing time of 70ms. The problem is that I do not observe almoust spin system of each aminoacid, in detail I see only cross peaks between NH-HA. I obtained very good results by 3d Noesy-hsqc edited. How can I do to improve the magnetization transfer along the spin system and see all cross peaks? Do you think that this problem is due to the nature?Thank you in advance\
Check if somebody has answered this question on NMRWiki QA forum
nmrlearner
News from other NMR forums
0
03-06-2012 06:17 PM
[U. of Ottawa NMR Facility Blog] Hsqc - tocsy
HSQC - TOCSY
There are many different NMR techniques used to probe molecular structure. Two very useful methods are the HSQC (or HMQC) sequence used to obtain heteronuclear coupling correlations and the TOCSY sequence used to look at extended homonuclear coupling correlations. These are among the most widely used pulse sequences by chemists to help elucidate the molecular structure of organic molecules. The sequences can also be combined into a single HSQC-TOCSY sequence which is simply an HSQC followed by a TOCSY spin lock. For the case of 1H and 13C in organic molecules, the HSQC-TOCSY...
(3, 2)D 1 H, 13 C BIRD r,X -HSQC-TOCSY for NMR structure elucidation of mixtures: application to complex carbohydrates
Linear Mode
