Molecular docking between human TMPRSS2 and the serine protease Kunitz-type inhibitor rBmTI-A

SARS-CoV-2 entrance into host cells is dependent of ACE2 receptor and viral protein S initiation by serine protease TMPRSS2. Cleavage of coronavirus protein S at the junctions Arg685/Ser686 and Arg815/Ser816 leads to the production of the S1/S2 and S2’ fragments needed for the fusion of viral and cell membranes. Studying and identifying serine protease inhibitors is an important step towards the development of candidate drugs to prevent SARS-CoV-2 infection. It has already been stablished that camostat mesylate, a serine protease inhibitor, is capable of blocking TMPRSS2 activity and prevent SARS-CoV-2 entrance into host cells. In this work, the interaction between the two domains of Kunitz-type serine protease inhibitor rBmTI-A and TMPRSS2 was studied through molecular docking. rBmTI-A domain 2 (P1 site Leu84) had the best complex results with predicted binding affinity of -12 Kcal.mol^-1 and predicted dissociation constant at 25°C of 1.6 nM. The results suggest that rBmTI-A is capable of binding TMPRSS2 cleavage site at the junction Arg815/Ser816 using essentially the same residues that camostat mesylate.