3.4.2 Helicase
Helicase (nsp13) is a critical multi-functional protein required for virus replication containing two main domains; N-terminal metal binding domain (MBD) and a conserved helicase domain at the C-terminus (Hel). In positive-sense RNA viruses, the enzyme separates nucleic acid and unfold the highly stable secondary structures within the genomic RNA to increase the efficiency of its translation (Adedeji et al., 2012a). Despite the essential function of helicase in virus multiplication, a few potential inhibitors of nsp13 have been reported so far (Adedeji et al., 2012b; Shum and Tanner, 2008).
A 1,2,4-triazole derivative, SSYA10-001, has shown inhibition effect on both helicase of SARS-and MERS-CoVs with EC50 values of 25 μM and 7 μM, respectively (Adedeji et al., 2014). In another study, Yu et al demonstrated that myricetin and scutellarein can inhibit the SARS-CoV helicase protein by affecting the ATPase activity (Yu et al., 2012). The potent inhibition of the helicase activities and replication of SARS coronavirus with EC50 of less than 10 μM is also reported by the Adamantane-derived Bananins (Tanner et al., 2005).