In silico prediction, molecular docking and binding studies of acetaminophen and dexamethasone to Enterococcus faecalis diaminopimelate epimerase

Enterococcus faecalis ( E . faecalis ) is a Gram‐positive coccoid, non‐sporulating, facultative anaerobic, multidrug resistance bacterium responsible for almost 65% to 80% of all enterococcal nosocomial infections. It usually causes infective endocarditis, urinary tract and surgical wound infections. The increase in E . faecalis resistance to conventionally available antibiotic has rekindled intense interest in developing useful antibacterial drugs. In E . faecalis , diaminopimelate epimerase (DapF) is involved in the lysine biosynthetic pathway. The product of this pathway is precursors of peptidoglycan synthesis, which is a component of bacterial cell wall. Also, because mammals lack this enzyme, consequently E . faecalis diaminopimelate epimerase ( Ef DapF) represents a potential target for developing novel class of antibiotics. In this regard, we have successfully cloned, overexpressed the gene encoding DapF in BL‐21(DE3) and purified with Ni‐NTA Agarose resin. In addition to this, binding studies were performed using fluorescence spectroscopy in order to confirm the bindings of the identified lead compounds (acetaminophen and dexamethasone) with Ef DapF. Docking studies revealed that acetaminophen found to make hydrogen bonds with Asn72 and Asn13 while dexamethasone interacted by forming hydrogen bonds with Asn205 and Glu223. Thus, biochemical studies indicated acetaminophen and dexamethasone, as potential inhibitors of Ef DapF and eventually can reduce the catalytic activity of Ef DapF.