- SARS (Severe Acute Respiratory Syndrome) virus is analogous to SARS-CoV-2. Both viruses share the same beta corona virus genus (lineage B). One of the crucial step for disease progression caused by novel SARS-CoV-2 involves the entry of virus into the cell. The virus entry inside the host cell is facilitated by the release of spike fusion peptide that is formed by cleavage of spike protein by the host protease. The receptor binding domain similarity of both SARS-CoV-2, delineates that ACE2 receptor is shared by both these viruses. In this research we have studied the structural similarity of COVID-19 surface glycoprotein. Protein sequence of COVID-19 surface glycoprotein was retrieved from NCBI database with Accession number: YP_009724390.1. Protein BLAST was done against PDB database to identify similar proteins. Similar proteins were identified fromMiddle East respiratory syndromerelated coronavirus, Severe acute respiratory syndrome coronavirus 2 (SARS),& other viruses PDB structures were downloaded. Homology modeling of COVID-19 surface glycoprotein was done using modeller tool and structural similarity was done using FATCAT tool. Result shows that spike protein of COVID-19 have 99% structural similarity with SARS spike protein with PDB ID:6VSB_A. Further binding sites were predicted using CASTp tool and binding sites were also compared with SARS spike protein, result shows that both proteins have similar binding sites. This study exemplifies structural similarity of COVID-19 spike protein (surface glycoprotein) with SARS virus spike protein and therefore can be considered conducive in drug repurposing of SARS inhibitors for COVID-19.

Keywords : COVID-19; SARS; Structural Similarity; Drug Repurposing; Homology Modeling