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.
Gupta
Geeta
G
Institute of Biotechnology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QT, UK.
Lowe
Christopher R
CR
D001665:Binding Sites; D001667:Binding, Competitive; D040761:Biomimetic Materials / Q000138:chemical synthesis* / Q000737:chemistry / Q000378:metabolism*; D002021:Buffers; D002846:Chromatography, Affinity; D020650:Combinatorial Chemistry Techniques; D015195:Drug Design; D006023:Glycoproteins / Q000737:chemistry / Q000378:metabolism*; D006027:Glycosides / Q000378:metabolism; D006031:Glycosylation; D007700:Kinetics; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D009961:Orosomucoid / Q000378:metabolism; D010504:Periodic Acid / Q000737:chemistry; D011485:Protein Binding; D013329:Structure-Activity Relationship; D013379:Substrate Specificity; D013816:Thermodynamics
D002021:Buffers; D006023:Glycoproteins; D006027:Glycosides; D008024:Ligands; D009961:Orosomucoid; D010504:Periodic Acid