Figure 4.

R1 peptide exhibits a strong binding affinity to S protein RBD. (A) Spike-RBD (20 μg/ml) was immobilized onto the NTA sensor chip by nickel coupling using 20 mM NiCl₂, and the ACE2 human receptor was injected at different concentrations (5, 10, 15 and 20 μg/ml) as positive control. (B) Affinity purified RBD (20 μg/ml) is immobilized onto carboxyl sensor chip, and R1 peptide was injected at different concentrations (5, 10, 15 and 20 μM) through the SPR flow cell. (C) ACE2 (20 μg/ml) was immobilized onto the sensor chip, and R1 was injected at 20 μM concentration as negative control.