An artificial receptor for glycoproteins

We describe the rational design, synthesis and development of a sterilizable biomimetic ligand for the affinity purification of glycoproteins. Based on mimicking the principles of natural carbohydrate recognition, a putative library of 196 glycoprotein‐binding synthetic ligands was designed and synthesized on a polymeric support. Ligand 11/11, based on a triazine scaffold and immobilized on a hydrophilic support, was identified as the ‘lead’ ligand. The carbohydrate recognizing the potential of the ‘lead’ ligand was revealed by reduced binding of a periodate oxidized model glycoprotein, and by ‘sharp’ elution profiles achieved with borate buffer eluents. Specific elution and competitive binding experiments determined the monosaccharide specificity of 11/11 in the order mannoside > glucoside > galactoside. The diastereo‐selective performance of ligand 11/11 was quantified and reaffirmed by analytical affinity chromatography and 1 H‐NMR, in the order galactoside < glucoside < mannoside with binding affinities ( K a , M −1 ) in the 63–214 and 20–83  M −1 range, respectively. Partition coefficient analysis revealed binding constants towards glycoproteins in the 10 4   M −1 range, that compared favourably with the affinities of carbohydrate binding lectins for glycoproteins, such as concanavalin A. Molecular modelling studies of ligand 11/11 revealed the formation of a pre‐organized apolar ‘tweezer‐like’ cavity, containing complementary nitrogenous hydrogen bond donor and acceptor groups that formed selective interactions with the equatorial 3‐ and 4‐hydroxyl groups of saccharides. Copyright © 2004 John Wiley & Sons, Ltd.