Fluorescence spectroscopic study on the interaction between praseodymium complex [Pr(C18H22.5N2O4)2] and bovine serum albumin

The interaction between praseodymium complex [Pr(C
18
H
22.5
N
2
O
4
)
2
] and bovine serum albumin (BSA) under physiological condition was investigated by fluorescence spectrum. The quenching mechanism of fluorescence was suggested as static quenching according to the Steru-Volmer equation. The binding constants between Pr(III) complex and BSA were 7.31×10
⁴
L·mol
⁻¹
(291K), and the binding sites were 1. The thermodynamic parameters ΔH, ΔS and ΔG were calculated at different temperatures indicated that the binding forces between Pr(III) complex and BSA were hydrogen bonds and van der Waals forces. According to the Förster non-radiation energy transfer theory, the binding average distance (r=2.84nm) between donor (BSA) and acceptor (Pr(III) complex) was obtained. Furthermore, the investigations of the synchromous fluorescence of the system reveal that the conformation of BSA is changed in the presence of Pr(III) complex.