Interaction of pyrrolizine derivatives with bovine serum albumin by fluorescence and UV–Vis spectroscopy

The interaction between pyrrolizine derivatives (PD) and bovine serum albumin (BSA) under imitated physiological conditions was analyzed by fluorescence and ultraviolet spectra. The experiments were conducted at three different temperatures (302, 306 and 310 K) and the results showed that PD caused the fluorescence quenching of BSA through a combined quenching procedure. The binding constant (Ka), binding-site number (n) between PD and BSA at different temperatures were obtained. According to Förster non-radiation energy transfer theory, the binding distance (r) between BSA and PD was calculated. The corresponding thermodynamic parameters (ΔG, ΔH, and ΔS) were also obtained. The comparison of binding potency of PD and BSA suggested that the substituent on the benzene ring could enhance the binding affinity of PD and BSA. Finally, we investigated the possible sub-domain on BSA where bind PD by displacement experiments.

Graphical abstractThe interaction between pyrrolizine derivatives (PD) and bovine serum albumin (BSA) was studied by fluorescence and UV–Vis spectroscopy. The quenching mechanism, binding constants, and binding distance were obtained. The comparison of binding potency of PD and BSA suggested that the substituents on the benzene ring influence the binding affinity of PD and BSA. We investigated the possible subdomain on BSA where bind PD by displacement experiments.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► We explored the interaction between PD and BSA by fluorescence spectroscopy. ► The fluorescence quenching mechanism was combined quenching. ► The binding constants and binding sites were calculated. ► The substituent on the benzene ring enhanced the binding affinity of PD and BSA. ► The possible sub-domain on BSA where bind PD was investigated.