Study on Interaction between Dy~(3+)and Bovine Serum Albumin by Spectrometry

In this paper,the interaction of rare earth ion Dy3 +and bovine serum lbumin( BSA) was studied by fluorescence spectrum and ultraviolet- visible absorption spectrometry and the conformational changes of BSA were investigated by synchronous spectroscopy and three- dimensional fluorescence spectra. It was shown that Dy3 +has a quite strong effect on the fluorescence quenching and UV absorption spectra enhancement of BSA. At the same time,the maximum emission peak of BSA shifted to long wave 5- 7nm. Analysis of the fluorescence quenching date according to Stern- Volmer equation indicates that the reaction between bovine serum albumin and Dy3 +generates the new complex- system. The quenching belongs to static fluorescence quenching when Dy3 +concentration is lower than 1. 212 × 10- 5mol·L- 1,and the static and dynamic quenching coexist when Dy3 +concentration is higher than 1. 212 x 10- 5mol· L- 1. The binding constants K A( 298K; 4. 1 × 103L·mol- 1,310K; 3. 9 ×103L·mol- 1) and all of the numbers of binding sites are 1. The thermodynamic parameter of binding reaction shows Dy3 +ions enter into the cavity in the substructure of BSA mainly by hydrophobic interaction and electrostatic force. Synchronous fluorescence spectrometry and three- dimensional fluorescence spectra show that Dy3 +ions affect micro-environmental and conformational changes of BSA molecules.