RESUMEN
Lawsone (2-hydroxy-1,4-naphtoquinone; LAW), as a naphthoquinone derivative, is the biologically active component of Henna leaves. In this study, the structural and functional effects of LAW on bovine liver catalase (BLC), has been studied utilizing ultraviolet-visible (UV-vis) absorption, fluorescence, and ATR-FTIR spectroscopic techniques, and molecular docking approach. In-vitro kinetic study showed that by adding gradual concentrations of LAW, catalase activity was significantly decreased through noncompetitive inhibition mechanism. UV-vis and ATR-FTIR spectroscopic results illustrated that additional concentration of LAW lead to significant change in secondary structure of the enzyme.The fluorescence spectroscopic results at different temperatures indicated that LAW quenches the intrinsic fluorescence of BLC by dynamic mechanismand there is just one binding site for LAW on BCL. Changing the micro-environment nearby two aromatic residues (tryptophan (Trp) and tyrosine (Tyr)) were resulted from synchronous fluorescence. The thermodynamic parameters were implied that the hydrophobic bindings have a significant impress in the organization of the LAW-catalase complex. Molecular docking data in agreement with experimental results, confirmed that hydrophobic interactions are dominant. Inhibition of enzyme activity by LAW, showed that along withits helpful effects as ananti-oxidant compounds, the side effects of LAW should not be overlooked.
RESUMEN
The aim of the project was to isolate and characterize bacteriocin-producing enterococci, as well as determine the prevalence of enterocin structural genes in 187 enterococcal clinical isolates from the northwest of Iran. The isolates were screened for antibacterial activity against 15 different indicator strains. The proteinaceous nature of the antimicrobial substances was confirmed by sensitivity to proteinase K; their stability to heat treatment was tested at 60 °C and 100 °C for 20 and 10 min, respectively. The PCR method was applied to detect previously identified enterocin genes. Our results showed that 38 (20.3%) of the enterococcal isolates were considered to be potential bacteriocinogenic strains. Furthermore, genes encoding diverse bacteriocin are highly distributed among clinical enterococci, and the strains with multi-bacteriocin genes displayed high antimicrobial activity. Enterocin A, enterolysin A, and enterocin L50A/B were the most abundant structural genes detected in bacteriocinogenic strains. This work is the first survey on the prevalence of bacteriocin genes among clinical enterococci in Iran that has isolated a strain with high antimicrobial activity and sensitivity to clinically relevant antibiotics.
