The steady‐state fluorescence anisotropy measurements were performed with a PerkinElmer LS55 spectrofluorometer using a quartz cuvette at room temperature as described by previous report (Pillai et al., 2015). Excitation and emission slits with a band pass of 5 nm were used for all measurements. The anisotropy values were calculated from the equation below,r=IVV−GIVHIVV+2GIVHwhere IVV and IVH are the measured fluorescence intensities with the excitation polarizer vertically oriented and emission polarizer vertically and horizontally oriented, respectively. G is the instrumental correction factor and is the ratio of the efficiencies of the detection system for vertically and horizontally polarized light and is equal to IHV/IHH.