The Structure of GSL

A GSL is composed of a hydrophobic ceramide and a hydrophilic sugar chain. Ceramide is made up of sphingosine, which consists of 14C-20C, and an aliphatic chain ranging from 16C to 26C. This aliphatic chain is connected to the sphingosine amino group through an amide bond. The sugar chains of glycosphingolipids are connected to the primary hydroxyl groups of ceramides through glycosidic bonds. These sugar chains can be either monosaccharides or polysaccharides. GSLs exhibit a much higher complexity compared to ceramides.

Glycosphingolipids are categorized into neutral and acidic glycosphingolipids based on their level of sialylation and sulfuration. Neutral glycosphingolipids are those without sialic acid structures or sulfated sugar chains. On the other hand, acidic glycosphingolipids are characterized by the presence of sialic acid structures or sulfated sugar chains.

Fig.1 Example of ¹H, ¹³C HSQC spectra and assignment of the signals to metabolites. (Tian, et al., 2007)

GSL Structure Analysis by ¹H,¹³C-Heteronuclear Singular Quantum Correlation (HSQC) at CD BioGlyco

The development of modern instrumental analysis technology has made great progress in the analysis of GLS. CD Bioglyco has developed NMR-based GSL Structure Analysis Services, which includes a variety of NMR analysis methods. The structural analysis of GLSs generally includes the following aspects:

• The number and types of monosaccharides contained in GSL.
• The structure of fatty chains in GSL.
• The connection between monosaccharides determination of sequence and connection sites, etc.

HSQC is a direct heteronuclear chemical shift correlation spectrum for H detection. The F dimension represents the chemical shift of ¹H, and the F1 dimension represents the chemical shift of ¹³C. The information given is the same as that of the directly detected CH-COZY spectrum. In the experiment, two ways of ¹³C decoupling and non-decoupling can be used. When ¹³C is used for decoupling, only one cross-peak of ¹³CH appears. When there is no ¹³C decoupling, there are two ¹³C ¹H cross peaks, that is, due to the coupling effect of ¹³C, the H connected to it splits into two peaks in the F1 dimension (¹³C direction). The distance between the two peaks is the ¹³C ¹H coupling constant.

Fig.2 Structural analysis of GSLs by NMR. (CD BioGlyco)

There are no diagonal peaks in the HSQC spectrum, and only cross peaks representing the C—-H coupling relationship of direct bonding are given. Each cross-peak represents the direct linkage relationship between protons and carbons corresponding to chemical shifts on the horizontal and vertical lines.

Advantages of Us

• HSQC test has high sensitivity and resolution.
• HSQC can be used to detect the ¹JCH correlation between C and H.
• Through HSQC, the signal of the carbon attached to the anomeric carbon proton and the signal of the carbon attached to each proton on the sugar group can be found.
• Comprehensive and reliable after-sales service

Based on comprehensive Carbohydrate Separation, Purification and Analysis solutions at CD BioGlyco, we provide accurate and reliable GSL structure analysis by ¹H,¹³C-HSQC. If you are interested in our services, please contact us for more details without any hesitation.

Reference

1. Tian, C.; et al. Top-down phenomics of Arabidopsis thaliana: metabolic profiling by one-and two-dimensional nuclear magnetic resonance spectroscopy and transcriptome analysis of albino mutants. Journal of Biological Chemistry. 2007, 282(25): 18532-18541.