ABSTRACT
The interaction between benzophenone (BP) and bovine serum albumin (BSA) was investigated by the methods of fluorescence spectroscopy combined with UV-Vis absorption and circular dichroism (CD) measurements under simulative physiological conditions. The experiment results showed that the fluorescence quenching of BSA by BP was resulted from the formation of a BP-BSA complex and the corresponding association constants (Ka) between BP and BSA at four different temperatures had been determined using the modified Stern-Volmer equation. The enthalpy change (ΔH) and entropy change (ΔS) were calculated to be -43.73 kJ mol(-1) and -53.05 J mol(-1) K(-1), respectively, which suggested that hydrogen bond and van der Waals force played major roles in stabilizing the BP-BSA complex. Site marker competitive experiments indicated that the binding of BP to BSA primarily took place in site I (sub-domain IIA). The conformational investigation showed that the presence of BP decreased the α-helical content of BSA and induced the slight unfolding of the polypeptides of protein, which confirmed some micro-environmental and conformational changes of BSA molecules.
