Investigation of the binding mechanism and inhibitory effect of 2-hydroxy-1,4- naphthoquinone on catalase activity and structure: multi-spectroscopic and computational study

2-hydroxy-1,4-naphthoquinone; HNQ as a naphthoquinone derivative, is the biologically active component of Henna leaves. In this study, the effects of HNQ on the structure and activity of bovine liver Catalase (BLC), has been studied using various kind of spectroscopic and theoretical methods including ultraviolet-visible (UV-vis) absorption, fluorescence, ATR-FTIR spectroscopy, and molecular docking studies. In vitro kinetic study showed that by adding gradual concentrations of HNQ, catalase activity was significantly decreased through noncompetitive inhibition mechanism. UV–vis and ATR-FTIR spectroscopic results illustrated that additional concentration of HNQ leads to significant change in secondary structure of the enzyme. The fluorescence spectroscopic results at two different temperatures demonstrated that HNQ can quench the intrinsic fluorescence of BLC through a dynamic mechanism.Changing the microenvironment around aromatic amino acids (tryptophan (Trp) and tyrosine (Tyr)) resulted from synchronous fluorescence. The thermodynamic parameters were implied thatBLC has one binding site for HNQ the hydrophobic interactions play an important role in the formation of the HNQ-BLC complex by a spontaneous process. Molecular docking data in agreement with experimental results in this study confirmed that hydrophobic interactions are dominant and there is only one binding site in the middle of the β-barrel, helical domain and wrapping domain of BLC for HNQ. Inhibitory effect of HNQ on BLC activity indicated that in addition to their beneficial impacts, they should not beoverlooked for their side effects.

کلیدواژه ها:

Bovine liver catalase ، 2-hydroxy-1 ، 4-naphthoquinone ، Antioxidant