In vitro interaction of sildenafil citrate (SC) with bovine serum albumin (BSA) was investigated at\ntwo excitation wavelengths of BSA (280 nm and 293 nm) at two different temperatures (298 K and\n308 K) by fluorescence emission spectroscopy. The study showed that quenching of BSA fluorescence\nby sildenafil citrate was the result of formation BSA-SC complex with probable involvement\nof both tryptophan and tyrosine residues of BSA. Fluorescence quenching constant was determined\nfrom Stern-Volmer equation, and both static quenching and dynamic quenching were showed for\nBSA by SC at the conditions. Van�t Hoff equation was used to measure the thermodynamic parameters\nG, H, and S at the temperatures which indicated that the hydrogen bond and the hydrophobic\nforces played major roles for BSA-SC complexation. The binding number (n) was found\nto be indicating that one mole BSA bound with one mole SC. The binding affinity of SC to BSA\nwas calculated at different temperatures. The binding constant was decreased with increasing\ntemperatures indicating that stability of BSA-SC complex decreased with increasing temperatures.
Loading....