Harnessing the Sars-cov-2 Spike Protein Binding Affinity to Ace2 Receptor Through Narcotinic Compounds Combined With Adjuvants: an in Silico Insight

Abstract Protein products of SARS-CoV-2 spike (S) coding gene sequence, were all analyzed and compared to other SARS-CoV S proteins to elucidate structural similarities of spike proteins. A homology modeling of SARS-CoV-2 S protein was obtained and used in molecular docking studies to find binding affinities of spike protein for angiotensin-converting enzyme 2 (ACE2). The two most important binding sites of S protein, namely, RBD and CTD, critically responsible for binding interactions, were identified. Finally, binding affinity of RBD and CTD domains of S protein with narcotic analgesics are studied. Moreover, interactions of ACE2 receptor- S protein with narcotic compounds when mixed with small molecule adjuvants to improve the immune response and increase the efficacy of potential vaccines, were taken into consideration. In-silico results suggest that the combination of narcotine hemiacetal with mannide monooleate shows a stronger binding affinity with CTD, while carprofen-muramyl dipeptide and squalene have stronger binding affinities for the RBD portion of S protein. Thus, a suitable combination of these narcotic is proposed to yield potent site-blocking efficacy for ACE2 receptor against SARS-CoV-2 spike proteins.