Abstract: The effects of rare earth ions (Y³⁺,La³⁺ and Lu³⁺) on the dynamic structure of HSA were studied by ²³Na NMR spectroscopy.The protein would be expanded and the mobilities of the molecular backbone would be enlarged by binding the rare earth ions,which would lead to the decrease of the correlation time (τ_c).There are three or more highly rare earth binding sites on HSA.The dynamic structural change is revelsible to some degrees,that is,the original state would be recovered if the highly binding rare earth ions were removed by chelating agents.

Key words: HSA, Rare earth ions, ²³Na NMR, Relaxation analysis