Sequence alignment of the SARS-CoV-2 and SARS-CoV spike protein sequences
Prior to performing the docking studies the multiple sequence alignment was carried out for the spike proteins of the novel corona virus, SARS-CoV-2 and the 2002 SARS-CoV (Supplementary Figure 1 and Table 1). These results show that there is a very high percentage identity (greater than 99%) among the spike protein of the novel corona virus SARS-CoV-2 strains. There was around 74% identity of the SARS-CoV-2 spike proteins with the 2002 SARS-CoV. Therefore, the SARS-CoV-2 spike protein is very much closer to SARS-CoV than to the other corona viruses as shown in other studies (Ahmed et al., 2020).
Figure 1.  The curcumin and its derivatives which displayed high binding affinity for SARS-CoV-2 and SARS-CoV spike proteins.
Table 1.  Percentage identity Matrix of Spike glycoprotein of SARS-CoV-2 and SARS-CoV. Indian 1 and 2 (QHS34546.1 and QIA98583.1), Korea (QHZ00379.1), Brazil (QIG55994.1), USA (QHO60594.1), Wuhan (QHD43416.1), Pakistan (QIQ22760.1), Italy (QIA98554.1), Australia (QHR84449.1) are spike proteins from SARS-CoV-2. SARS-6CRV is the spike protein from the 2002 SARS-CoV spike protein (6CRV).
Viral Strain  SARS-CoV  Indian1  Korea  Indian2  Brazil  USA  Wuhan  Pakistan  Italy  Australia
SARS-CoV  100  73.75  73.77  73.69  73.77  73.77  73.77  73.77  73.77  73.77
Indian1  73.75  100  99.84  99.84  99.92  99.92  99.92  99.92  99.92  99.84
Korea  73.77  99.84  100  99.84  99.92  99.92  99.92  99.92  99.92  99.84
Indian2  73.69  99.84  99.84  100  99.92  99.92  99.92  99.92  99.92  99.84
Brazil  73.77  99.92  99.92  99.92  100  100  100  100  100  99.92
USA  73.77  99.92  99.92  99.92  100  100  100  100  100  99.92
Wuhan  73.77  99.92  99.92  99.92  100  100  100  100  100  99.92
Pakistan  73.77  99.92  99.92  99.92  100  100  100  100  100  99.92
Italy  73.77  99.92  99.92  99.92  100  100  100  100  100  99.92
Australia  73.77  99.84  99.84  99.84  99.92  99.92  99.92  99.92  99.92  100