Mechanistic investigation on binding interaction of bioactive imidazole with protein bovine serum albumin—A biophysical study

The interaction between bioactive imidazole derivative (PPP) and bovine serum albumin (BSA) was investigated using fluorescence and UV–vis spectral studies. The experimental results showed that the fluorescence quenching of BSA by imidazole derivative was the result of the formation of BSA–PPP complex and the effective quenching constants (KSV) were 2.66 × 104, 2.56 × 104, and 2.10 × 104 at 301, 310 and 318 K, respectively. Static quenching and non-radiative energy transfer were confirmed to the result in the fluorescence quenching. The binding site number n, apparent binding constant KA and corresponding thermodynamic parameters (ΔG, ΔH and ΔS) were measured at different temperatures. The process of binding of PPP molecule on BSA was a spontaneous molecular interaction procedure in which entropy increased and Gibbs free energy decreased.

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► FRET studies – The emission band of BSA and PPP are very close – FRET characteristic.
► Energy transfer efficiency – Values of E, R0, r0 shows that energy could transfer from BSA to PPP.
► Forester's distance – R0 < 8 nm – shows static quenching and energy transfer from BSA to PPP.
► Thermodynamic parameters – Values of ΔG, ΔH and ΔS shows electrostatic interaction between BSA and PPP system.
► Synchronous fluorescence spectroscopic studies of BSA – Dissociation of −OH group in the tyrosine residue by PPP leads to quenching.