Curcumin, a Natural Antioxidant, Acts as a Noncompetitive Inhibitor of Human RNase L in Presence of Its Cofactor 2-5A In Vitro
Figure 4
Curcumin binds to human RNase L directly with high affinity. (a) Effect of curcumin on the total intrinsic fluorescence of the purified human RNase L (GST-RNase L) protein (1 μM) in buffer (50 mM Tris.Cl (pH 7.5), 200 mM NaCl, and 5 mM β-ME). Fluorescence emission spectra indicate quenching and blue shift of the fluorescence intensity of human RNase L during the titration by increasing curcumin concentration (0.25 μM to 16 μM). (b) Saturation curves were generated from the intrinsic fluorescence data by plotting the change in fluorescence intensity at 340 nm as a function of increasing curcumin concentration, where and are fluorescence intensity in the absence and presence of curcumin, respectively. , determined by the fit of fluorescence intensity on the Hill plot, was 0.397 ± 0.018 μM. Excitation wavelength of 280 nm was used.
