Research Article

Curcumin, a Natural Antioxidant, Acts as a Noncompetitive Inhibitor of Human RNase L in Presence of Its Cofactor 2-5A In Vitro

Figure 2

Effect of curcumin on RNase L activity. 1.2% agarose-TBE gel showing inhibition of RNase L activity with purified GST-hRNase L, 2-5A (10 nM), and in absence and presence of 5 μM and 10 μM curcumin, respectively. Panel (a): control lanes with no 2-5A cofactor, panel (b): activity in presence of 2-5A cofactor and no curcumin, panels (c) and (d): inhibition in activity in presence of 5 μM and 10 μM curcumin, respectively. Panels (a) and (b) as well as panel (c) and (d) are parts of the same gels 1 and 2 (both 18 lanes) with control lanes of 2 μg RNA loaded onto each gel for intensity normalization and empty lanes for background subtraction. RNase L activity was calculated from the decrease in the intensity of ribosomal RNA bands, which were converted into pmol/min RNA degraded as mentioned in materials and methods. (e) Plot generated by fitting the data to nonlinear regression analysis, which gave a of 4.136 μM. Square bracket encompassing 28S and 18S rRNA bands depict the area used for intensity calculations.
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