Characterization of the interaction of the anti-properdin IgG with their antigen by Surface plasmon resonance (SPR)
The interaction of the IgG with properdin was analyzed in real time using a ProteOn XPR36 SPR equipment (BioRad, Marne-la-coquette, France) and BiaCore2000 (GE Healthcare, France). Properdin was covalently immobilized to a GLC sensor chip (BioRad) following the manufacturer’s procedure. Alternatively, CM5 chips for BiaCore were used. Protein G purified IgG from LN patients or healthy donors were injected for 300s at 6 different concentrations (300, 150, 75, 35, 17.5 and 0 µg/ml) diluted in PBS 0.005% Tween or 10mM Hepes, 145mM NaCl, 0,005% Tween 20 running buffers. The dissociation was followed for 300s. Bound protein was regenerated with 1M NaCl, 50mM NaOH regeneration buffer.