Studies on interaction between an imidazole derivative and bovine serum by spectral methods

The interaction between a trifluoromethyl substituted imidazole derivative 2-(4-(trifluoromethyl)phenyl)-1-phenyl-1H-imidazo[4,5-f] [1,10] phenanthroline (tfmppip) and bovine serum albumin (BSA) was investigated by solution spectral studies. The observed experimental result shows that the imidazole derivative has strong ability to quench the fluorescence of BSA by forming complex which is stabilized by electrostatic interactions. The effective quenching constants (ksv) were 2.79 × 104, 2.51 × 104, and 2.32 × 104 at 301, 310 and 318 K respectively. The Stern–Volmer quenching constant (Ksv), binding site number (n), apparent binding constant (KA) and corresponding thermodynamic parameters (ΔG, ΔH and ΔS) were calculated. The distance between the donor (BSA) and acceptor (tfmppip) was obtained according to fluorescence resonance energy transfer (FRET). Conformational changes of BSA were observed from synchronous fluorescence technique. The effect of metal ions such as Cu2+, Zn2+, Ca2+, Mg2+, Ni2+, Co2+ and Fe2+ on the binding constants between the imidazole derivative and BSA were also studied.

Figure optionsDownload as PowerPoint slideHighlights
► The interactions between tfmppip and BSA were investigated by fluorescence quenching.
► Quenching mechanism mainly arise from the formation of BSA-imidazole complex.
► The D → A distance is <8 nm indicates that the energy transfer from BSA to dfppip.
► Synchronous fluorescence spectra to exploit the structural change of BSA.
► The effect of other ions on the binding constants between dfppip and BSA.