3.3.1.2 3C-like main protease (3CLpro)
3CLprotease (which is the main protease (Mpro)) or nsp5 directly mediates the processing of the viral polyprotein and maturation of viral nonstructural proteins (nsps), which are essential in the life cycle of the virus. Initiation of viral RNA synthesis and switching translation to RNA replication are other functions of this protein. 3CLpro is among the most attractive target for anti-coronavirus drug development. Based on a computational drug repurposing study performed by Junmei Wang (Wang, 2020), five drugs, namely, Carfilzomib, Eravacycline, Valrubicin, Lopinavir and Elbasvir, are identified to have inhibitory activities on 3Cl pro of 2019-nCoV. According to another computational study performed by Nguyen et al., Bortezomib, Flurazepam, Ponatinib, Sorafenib, Dasatinib, are five potent potential inhibitors of 3CL pro for 2019-nCoV (Nguyen et al., 2020).
Due to the similar active-site architecture of the 3C protease in coronaviruses and enteroviruses, Zhang et al designed peptidomimetic α-ketoamides as suitable targets for the development of broad-spectrum antiviral drugs. They introduced a compound (11r) expecting to exhibit excellent antiviral activity against 2019-nCoV (Li and De Clercq, 2020; Zhang et al., 2020b)