Proteases of SARS Coronaviruses

Coronaviruses such as SARS and SARS-CoV-2 have established themselves as a global health concern after causing an epidemic and a pandemic in the last twenty years. Understanding the life cycle of such viruses is critical to reveal their pathogenic potential. As one of the essential viral enzymes, SARS proteases are indispensable for the processing of viral polypeptides and for the replication of the virus. SARS-CoV and SARS-CoV-2 encode for 2 viral proteases: the main protease (3CLpro) and the papain-like protease (PLPro), which are conserved among different coronaviruses and are absent in humans. This review summarizes the existing literature on the structure and function of these proteases; highlighting the similarity and differences between the enzymes of SARS and SARS-CoV-2. It also discusses the development of inhibitors to target viral proteases.