A Fluorescence Study on the Interactions of Cationic Lipids with Bovine Serum Albumin

Interactions of a series of dialkyl cationic lipids linking with bovine serum albumin (BSA) through acetal (linker) have been studied by the fluorescence spectroscopy. At low concentrations of cationic lipids, the fluorescence intensity of BSA decreased with binding of cationic lipid, and the maximum of emission wavelength shifted from (344±1)nm to (331±1)nm. It indicates that the BSA goes to uncoiled flexible conformation from its native structure. When the concentrations of lipids increased, the fluorescence intensity increased rapidly and then maintained unchanged. It reveals that two tryptophan residues of BSA are all enwrapped in the bilayer membrane, owing to the hydrophobic interactions between lipids and BSA.