Differential scanning calorimetric studies of the glycoprotein, winged bean acidic lectin, isolated from the seeds of Psophocarpus tetrogonolobus

Abstract

Differential scanning calorimetry of solutions of WBAII and in presence of sugar ligands shows that WBAII dimer dissociates to its constituent monomeric subunits at the denaturation temperature. The thermal denaturation of WBAII consists of the unfolding of two independent domains of WBAII similar to that of basic winged bean lectin and ECorL and in contrast to concanavalin A (conA), pea and lentil lectin, which unfold as single entities. Apparently, the glycosylation reduces the structural integrity of WBAII as compared to conA, pea and lentil lectin. The increase in the denaturation temperature of the sugar-lectin complexes yields binding constants close to the binding constants extrapolated from the ITC results and confirms the mechanism proposed for its thermal unfolding.