Spectroscopic investigation of the interaction between riboflavin and bovine serum albumin

The mutual interaction of riboflavin (RF) with bovine serum albumin (BSA) was investigated using fluorescence spectroscopy under simulative physiological conditions. The fluorescence quenching mechanism of BSA by RF should belong to dynamic quenching according to the Stern-Volmer equation, but also the effect of ground complex formation and energy transfer could not be completely precluded in BSA-RF system. The binding constants and the corresponding thermodynamic parameters at different temperatures were calculated, which indicated the presence of hydrophobic forces between RF and BSA. The averaged binding distance between riboflavin and BSA was also obtained based on the theory of FOrster's non-radiation energy transfer. Moreover, the effect of riboflavin on the conformation of BSA was analyzed using synchronous fluorescence. The effects of some common ions Cu2+, Zn2+, Ca2+, and Mg2+ on the binding constant between riboflavin and BSA were also examined. (C) 2009 Elsevier B.V. All rights reserved.