Related Experiment Video
Updated: May 29, 2026
14:55
Atomic Scale Structural Studies of Macromolecular Assemblies by Solid-state Nuclear Magnetic Resonance Spectroscopy
Published on: September 17, 2017
Automatic structure determination of regular polysaccharides based solely on NMR spectroscopy
Magnus Lundborg1, Carolina Fontana, Göran Widmalm
1Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, S-106 91 Stockholm, Sweden.
Biomacromolecules
|September 30, 2011
Summary
This study introduces a new NMR spectroscopy method for determining polysaccharide structure and sugar configuration. The technique uses butanolysis and computer-assisted analysis for automatic and efficient structural elucidation.
Area of Science:
- Carbohydrate Chemistry
- Analytical Chemistry
- Spectroscopy
Background:
- Structural analysis of polysaccharides is crucial for understanding their biological functions.
- Determining sugar components and their absolute configurations is a key challenge in polysaccharide research.
Purpose of the Study:
- To develop a novel, automated method for polysaccharide structural analysis using NMR spectroscopy.
- To enable efficient determination of sugar composition and stereochemistry.
Main Methods:
- Utilizing butanolysis with chiral 2-butanol derivatives to form 2-butyl glycosides.
- Employing Nuclear Magnetic Resonance (NMR) spectroscopy to obtain characteristic (1)H and (13)C chemical shifts.
- Implementing computer-assisted structural determination (CASPER) solely based on NMR data.
Main Results:
- Successfully demonstrated the automated structural determination of polysaccharides using NMR data.
- Obtained characteristic NMR chemical shifts for 2-butyl glycosides, facilitating analysis.
- Validated the CASPER system for fully automatic structural elucidation.
Conclusions:
- The developed NMR-based method provides an efficient and automated approach for polysaccharide structural analysis.
- This technique simplifies the process by requiring reference data to be prepared only once.
- The method is advantageous for researchers needing to determine the structure and absolute configuration of unknown polysaccharide samples.
Related Concept Videos
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...
01:30NMR and Mass Spectroscopy of Carboxylic Acids
In ¹H NMR spectroscopy, acidic protons (–COOH) of carboxylic acids are highly deshielded and absorb far downfield, at around 9–12 ppm. The chemical shift value depends on the concentration and solvent used.
While α protons of carboxylic acids absorb at 2–2.5 ppm, β protons absorb further upfield.
Carboxylic acids are easily identified by dissolving them in deuterium oxide, which results in a rapid exchange of the acidic protons with deuterium. This leads to the disappearance of the acidic...
While α protons of carboxylic acids absorb at 2–2.5 ppm, β protons absorb further upfield.
Carboxylic acids are easily identified by dissolving them in deuterium oxide, which results in a rapid exchange of the acidic protons with deuterium. This leads to the disappearance of the acidic...
01:24Mass Spectrum: Interpretation
An unknown compound can be established by identifying the molecular ion peak in the mass spectrum. The molecular ion peak is often weak or absent due to the predominance of fragmentation in high-energy electron beams. In such cases, a soft-energy electron beam can be used to scan the spectrum to enhance the intensity of the molecular ion peak. Additionally, chemical ionization, field ionization, and desorption ionization spectra are used to obtain a relatively intense molecular ion peak.To...
01:26Spectroscopy of Carboxylic Acid Derivatives
Infrared spectroscopy is primarily used to determine the types of bonds and functional groups. In carboxylic acid derivatives, a typical carbonyl bond absorption is observed around 1650–1850 cm−1. For esters, the absorption is recorded at around 1740 cm−1, while acid halides show the absorption at about 1800 cm−1. Another acid derivative, the acid anhydrides, exhibit two carbonyl absorption around 1760 cm−1 and 1820 cm−1, arising from the symmetrical and unsymmetrical carbonyl vibration.
In the...
In the...
01:26Biosynthesis of Polysaccharides
Polysaccharides such as glycogen and starch are synthesized from nucleoside diphosphate sugars, primarily uridine diphosphate glucose (UDPG) and adenosine diphosphate glucose (ADPG). These activated glucose donors act as key intermediates in carbohydrate metabolism and biosynthesis. UDPG primarily involves glycogen synthesis in animals and many bacteria, while ADPG plays a fundamental role in starch synthesis in plants and certain bacteria.UDPG is formed when glucose-1-phosphate reacts with...
01:14NMR Spectroscopy of Aromatic Compounds
Aromatic compounds can be identified or analyzed using proton NMR and carbon‐13 NMR. Typically, aromatic hydrogens or hydrogens directly bonded to the aromatic rings are strongly deshielded by the aromatic ring current. Therefore, they absorb in the range of 6.5–8.0 ppm in proton NMR spectra. For instance, aromatic hydrogens directly bonded to the benzene ring absorb at 7.3 ppm. However, aromatic hydrogens of larger rings absorb farther upfield or downfield than the ideal range. Consider...