Archives des Measuring Carbohydrate-Lectin Interactions: A Guide for Beginners

Fig.1: Crystal structures of lectins from different pathogens. Proteins are complexed with their carbohydrate ligands (cyan). PDB codes (top to bottom): 1HGG, 1OKO, 4D4U.

How do Lectin Read the “Glyco Code”

Of all the building blocks of life, glycans are the most abundant and diverse family of organic molecules, which informational

Fig. 3: The multivalency effect can be deconvoluted in more distinct mechanisms.

Understanding Multivalency

Often possessing more than one binding site, lectins are thus intrinsically multivalent receptors that can interact with multiple copies of

Table 1: An overview on pros and cons of the most common techniques to study carbohydrate-lectin interactions.

Measuring Carbohydrate-Lectin Interactions

When studying the role of lectin in biology or when assessing the capability of new therapeutics in (dis)regulating these functions,

Fig. 5: Schematic representation of an ITC machine and the elaboration of detected signal (raw data in grey).

In solution Assays: Isothermal Titration Calorimetry

Isothermal Titration Calorimetry (ITC) is considered the method of choice to analyse protein-carbohydrate interactions. It allows the precise determination of

Fig. 6: A schematic representation of the Fluorescent Polarization technique. Free fluorescent ligand in solution rotates fast and depolarizes light (top). The same ligand in a direct binding assay leaves light highly polarized (middle). Inhibitor displaces ligand from the binding pocket during the competitive binding assay (down).

In Solution Assays: Fluorescence Polarization

Fluorescence polarization (FP) is a powerful tool in biochemical research. This method has historically been applied to the study of

Fig. 7: A schematic representation of the hemagglutination inhibition assay.

In Solution Assays: Hemagglutination Inhibition

In the early history of lectin research, the most common method to identify lectin activity was to check the ability

Fig. 8: A zoom in the ELLA sample well: HRP reveals surface-bound lectin by converting a colourless compound into a yellow product.

On Surface Assays: Enzyme-Linked Lectin

The enzyme-linked lectin assay (ELLA) was introduced in 1983 by McCoy et al. (. McCoy et al., 1983 ) as a variation

Fig. 9: A direct binding experiment by SPR, in which the lectin is immobilized and the ligand flows over it.

On Surface Assays: Surface Plasmon Resonance

The phenomenon of surface plasmon resonance (SPR) was observed for the first time by Wood more than a century ago

Conclusions and Outlook

The relevance of carbohydrate-lectin interactions in controlling many physiological processes is key to various disciplines. However, the understanding of the

Bibliography

Andre, S.; Pieters, R. J.; Vrasidas, I.; Kaltner, H.; Kuwabara, I.; Liu, F. T.; Liskamp, R. M. J.; Gabius, H.