Interaction of aromatic imino glycoconjugates with jacalin: experimental and computational docking studies

Altering the lectin properties by chemically modified glycoconjugates can have profound effect on their biological applications. In the present case, jacalin has been chosen to study the binding aspects toward glycoconjugates modified by connecting aromatic moieties through imine conjugation at their C-1- or C-2-positions. Out of 10 glycoconjugates, the galactosyl-naphthyl imine (1c) was found to be most effective toward agglutination inhibition (260 times better than galactose), quenching fluorescence intensity, and exhibiting greater binding (K(a), 1.3 × 10(4)M(-1)) with jacalin. The specific binding of galactose conjugates and the nonspecific binding of other conjugates have been demonstrated based on ITC. Changes in the secondary structures have been addressed by far- and near-UV CD spectroscopy. The present studies demonstrated that galactose-based conjugates bind at carbohydrate recognition domain (CRD) mainly through polar interactions in addition to exhibiting some nonpolar/hydrophobic interactions, whereas the conjugates other than galactose primarily interact through hydrophobic interactions. Binding of galactosyl conjugates at CRD has been further demonstrated by rigid docking.