The pandemic coronavirus disease 2019 () is caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). As a first step of the viral replication strategy, the virus attaches to the host cell surface before entering the cell. The Spike protein recognizes and attaches to the Angiotensin-Converting Enzyme 2 (ACE2) receptor found on the surface of type I and II pneumocytes, endothelial cells, and ciliated bronchial epithelial cells. Drugs targeting the interaction between the Spike protein of SARS-CoV-2 and ACE2 may offer some protection against the viral infectionThe SARS-CoV-2 Spike S1:ACE2 Inhibitor Screening Colorimetric Assay Kit is designed for screening and profiling inhibitors of this interaction. The key to this kit is the high sensitivity of detection of ACE2-Biotin protein by Streptavidin-HRP. Only a few simple steps on a microtiter plate are required for the assay. First, Spike S1 protein is attached to a 96-well transparent plate. Next, ACE2-Biotin is incubated with Spike S1 on the plate. Finally, the plate is treated with streptavidin-HRP followed by addition of an HRP substrate to produce color, which can then be measured using a UV/Vis spectrophotometer microplate reader.