Comparative studies on lectin-carbohydrate interactions in low and high density homo- and heteroglycoclusters

A versatile synthetic procedure to construct series of high- and low-density homo- and heteroglycoclusters is reported. The binding properties of these synthetic multivalent glycoconjugates to concanavalin A (Con A), a model lectin, have been assessed by using a range of competitive and non-competitive binding assays including enzyme-linked lectin assays (ELLA), isothermal titration microcalorimetry (ITC) and surface plasmon resonance (SPR). In all cases, highly dense glycoclusters showed a substantial amplification of the lectin-binding strength in comparison with low-density counterparts. Interestingly, highly-dense glycoligand presentations, regardless of their homo- or heteroglycoligand pattern, furnished similar Con A binding properties, supporting the existence of a synergic effect (heterocluster effect) due to secondary interactions of "non-active" structural motifs in the presence of a certain density of "active" glycoligands.