Spectral study on the interaction of nightblue and bovine serum albumin

The interaction between night blue and bovine serum albumin was studied by fluorescence spectroscopy.The experimental results showed that the intrinsic fluorescence of BSA was quenched by NB,and the quenching mechanism of the combination of NB with BSA was a static quenching procedure.The number of binding sites and the apparent binding constants at different temperatures were obtained from the analysis of the fluorescence quenching data,and the number of binding sites was 1 approximately.The analysis of thermodynamic parameters indicated that the action process between the molecules was carried out spontaneously,and the action was caused by electrostatic and hydrophobic forces.Synchronous fluorescence showed that the binding site of NB with BSA was near to be combined by tryptophan subunit.The shortest binding distance and the energy transfer efficiency between the acceptor(BSA) and the donor(NB),obtained by Forster's nonradiative energy transfer mechanism,were 0.270 and 2.75 nm.