Using the Biacore Surface Plasmon Resonance (SPR) technique, we have quantified the kinetic receptor binding parameters for COVID-19 / SARS-CoV-2 ‘spike’ protein to the trans-membrane receptor Angiotensin Converting Enzyme 2 (ACE2). Notably, when ACE2 is pre-mixed with spike protein (at 14-fold excess), it binds to spike protein in solution, preventing it from binding to the ACE2 receptor on the sensor surface. This indicates that soluble ACE2 could be used to “decoy” spike protein on the SARS-CoV2 virus, potentially reducing or blocking viral infectivity.
figure SARS-CoV-2 spike protein (10 nM) gives a positive binding response to recombinant human ACE2 immobilised onto a CM5 sensor (blue line). ACE2 (140 nM) in solution does not bind to immobilised ACE2 (only a small bulk effect; yellow line). Mixing spike protein (10 nM) and ACE2 (140 nM) in solution, then co-injection onto the sensor, significantly reduces spike binding to immobilized ACE2 (green line).