The inhibitory effect of farnesiferol C against catalase; Kinetics, interaction mechanism and molecular docking simulation.

Farnesiferol C (FC) is a natural sesquiterpene coumarin, which includes a widely range of biological activities. In this work, effects of FC on the structure and catalytic function of bovine liver catalase (BLC) was assessed by various spectroscopic and theoretical methods. Kinetic studies showed that FC has a remarkable inhibitory activity on BLC via mixed-type inhibition. The IC50 value as the inhibitory strength of FC was evaluated 1.5μM. Fluorescence spectroscopy, synchronous fluorescence, CD spectroscopy and UV-vis absorption studies revealed conformational changes in the tertiary and secondary structure of BLC as well as the position of the heme group in the presence of different concentrations of FC. Fluorescence studies revealed that FC quenches intrinsic emission of catalase via static quenching process. The binding constants at 298 and 310K were calculated 1.17×105 M-1 and 1.0×105 M-1 , respectively. Thermodynamic data suggested that hydrophobic interactions play a major role in the binding reaction of FC on BLC. Structural studies indicated that the binding FC to the enzyme is responsible for the changes of the percentage of secondary structures' elements especially α-helix. From the simulation data, the role of Arg353 residue in the mechanism of catalase inhibition has been recognized.