Öz
Coronaviruses (CoVs) are a group of ribonucleic acid (RNA) viruses that can cause respiratory, intestinal and central nervous system infections in humans and animals. Especially two strains caused severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle East respiratory syndrome coronavirus (MERS-CoV). In addition to these strains, SARS-coronavirus 2 (SARS-CoV-2), appeared in Wuhan, China in December 2019. It soon affected the whole world and was declared a pandemic by the World Health Organization. The disease caused by the SARS-CoV-2 virus is called coronavirus disease (Covid-19). There are studies in the literature, infection mechanism of Covid-19, is binding of the virus to the receptor of angiotensin converting enzyme-2 (ACE2) and subsequently internalization of the complex by the host cell. The recognition of ACE2 as a co-receptor for SARS-CoV-2 suggest that there is cellular entry in ACE2 expressing tissues, including lung, heart, kidney, brain and intestine. The studies, have extensively studied the RBDACE2 complex, spike protein, and free RBD systems of SARS-CoV-2 and SARS-CoV using protein-protein docking and molecular dynamics simulations. The free binding energy of SARS-CoV-2 to RBD-ACE2 has been shown to be lower than the free binding energies of other coronavirus types. It was emphasized that this situation could be related to the more contagious SARS-CoV-2. While it seems such as clear that SARS-CoV-2 infects with binding mechanism the human ACE2 receptor of the RBD domain, the molecular mechanisms still remain mysterious. The present findings are expected to be useful for the disease prevention and control as well as drug and vaccine development of Covid-19.