Interactions between N-Cetyl-Hydroxyethyl-Dimethyl Ammonium Bromide and Bovine Serum Albumin

Interactions between N-cetyl-hydroxyethyl-dimethyl ammonium bromide(CHDAB)and bovine serum albumin(BSA)in Tris-HCl buffer solution(pH=7.1)were studied by fluorescence spectroscopy at 298 K.Effects of BSA concentration on the interactions were examined.The interaction mechanism between BSA and CHDAB at a relatively low concentration range was discussed using the Stern-Volmer equation.The binding constant KA and the number of binding site n of the interaction between CHDAB and BSA were calculated using site binding mode.The addition of CHDAB on the conformation of BSA was analyzed using synchronous fluorescence spectrometry.Results showed that CHDAB has a fluorescence quenching effect on BSA and leads to a blue shift of the maximum emission wavelength.At the same temperature,both the Stern-Volmer quenching constant and the binding constant increase with decreasing concentration of BSA,which indicates that stronger binding and fluorescence quenching are observed at lower concentration of BSA.The measurements of synchronous fluorescence spectrometry on tyrosine residues and tryptophan residues also show that the existence of CHDAB has an effect on the conformation of BSA.