Surface plasmon resonance measurements of Fab binding affinity
Binding affinities and kinetics of 2C06 and 2C09 antibodies were assessed by surface plasmon resonance (SPR) on a Biacore S-200 (GE Healthcare) at 25°C in HBS-P+ buffer (10 mM HEPES, pH 7.4, 150 mM NaCl and 0.05% surfactant P-20). Glycan-reactive 2G12 IgG was immobilized onto a CM5 chip by amine coupling to 8000–10000 response units (RU). BG505 DS-SOSIP at 25 nM were captured to the sample channel at 300 RU on the 2G12 sensor chip. Serial two-fold diluted 2C06 and 2C09 Fabs were passed through the sample and reference channels for 180 s followed by a 300 s dissociation phase at 30 μL/min. The surface was regenerated by flowing 3 M MgCl