Selective Binding of RNAse B Glycoforms by Polydopamine-immobilized Concanavalin A
Todd A. Morris, Alexander W. Peterson, Michael J. Tarlov
Glycoanalysis is important in the manufacture and quality control of protein therapeutics. An emerging method for glycoanalysis is the use of lectin arrays. Critical to the performance of these arrays is the immobilization of the lectin molecules. Polydopamine has recently been shown to adsorb to a wide variety of surfaces. In this study, polydopamine (pDA) was used to modify gold, indium, and iridium surfaces and promote the adhesion of the alpha-mannose-specific lectin Concanavalin A (Con A). The activity of the surface-bound lectin was demonstrated with the alpha-mannose-presenting glycoprotein Ribonuclease B (RNAse B). Surface plasmon resonance spectroscopy (SPRS) was used to demonstrate the selectivity affinity of RNAse B for Con A. By Scatchard plot analysis of the SPRS data, a dissociation constant of 4 micromolar was determined for RNAse B and immobilized Con A. Surface-MALDI-TOF MS experiments revealed that the affinity of Con A/pDA for the glycoforms of RNAse B is significantly affected by slight variations in oligosaccharide structure or composition. Specifically, Con A binds certain Man7, Man8, and Man9 RNAse B glycoforms more strongly than Man5 and Man6 glycoforms.
concanavalin A, glycoanalysis, glycoproteins, lectins, ribonuclease B