customer service
Reader Domain Proteins







SARS-CoV-2 S protein and ACE2 Binding Assay


Virus entry into host cells is a crucial step in the virus replication cycle of SARS-CoV-2 which offers promising targets for viral therapeutics. SARS-CoV-2 is lined with large spike (S) proteins which engage the host cell protein ACE2 (Angiotensin-converting enzyme 2), which serves as a receptor for virus entry. After binding of S protein to the ACE2, endocytosis is induced, and ACE2, together with the virus, enters the host cell via the endocytic vesicle.

Several strategies are currently being explored to prevent virus entry of SARS-CoV-2 into host cells:

  • 1. Development of molecules that occupy the host cell’s ACE2 receptors to prevent the virus from attaching.
  • 2. Development of molecules that bind and saturate the S protein on the virus surface such that binding to ACE2 is limited or cannot occur.
  • 3. Development of molecules that inhibit TMPRSS2 preventing the activation of the S protein (see our protease assays for further information).
Surface plasmon resonance assay


Two assays were developed at Reaction Biology to investigate the binding interaction between the receptor binding domain of the viral S protein and ACE2. These assays can be used to measure the direct binding of potential therapeutics to the S protein receptor binding domain or ACE2 to determine the kinetics of the interaction or to measure whether the test molecule(s) disrupt the S protein /ACE2 interaction.

View Full Data Sheet



ACE2 was captured to the sensor chip and soluble S1 receptor binding domain was used as the analyte (shown in various concentrations) to validate the binding behavior. Using this assay set-up, the binding of molecules to ACE2 can be measured to determine the binding kinetics of the molecule/ACE2 interaction and probe whether the molecules interfere with the ACE2/S protein interaction.


S1 receptor binding domain was captured to the sensor chip and soluble ACE2 was used as the analyte (shown in various concentrations) to validate the binding behavior. Using this assay set-up, the binding of molecules to the receptor binding domain of the S protein can be measured to determine the binding kinetics of the interaction and probe whether the molecules interfere with the S protein /ACE2 interaction.

The data were generated with a Biacore 8K instrument and show similar binding affinity for the binding event in both directions, binding of S protein to ACE2 and binding of ACE2 to S protein. The on-rate is slightly faster for S protein (analyte) binding to ACE2 (target), while the off-rate is slightly slower for ACE2 (analyte) binding to S protein (target). However, the values are within a 3-fold range which shows consistency in the kinetics of the binding event in both directions.

SPR allows evaluation of several parameters:

1. Probe the direct binding kinetics (on/off-rate and KD), which can be used to optimize target engagement (on-rate) and residence time on the target (off-rate) to ensure a tight binding interaction.
2. New drug candidates can be screened for their potential to block the interaction of S1 receptor binding domain and ACE2 receptor with a throughput of up to 2300 compounds per day.















With the largest functional kinase activity assay panel in the industry, RBC provides kinase, epigenetic, and other profiling services to over 750 companies worldwide. RBC specializes in custom assay conditions, high quality reproducible data, and outstanding service.

Reaction Biology Corp. 1 Great Valley Parkway, Suite 2 Malvern, PA 19355 1-877-347-2368 or 610-722-0247
Sales@reactionbiology.com
Reaction Biology Corp. © 2016 all rights reserved.