A study of the dynamic structure of human serum albumin by the spin probe method

The possibility of studying the dynamic properties of the human serum albumin (HSA) protein globule by the spin label and probe method was analyzed. The dependence of the rotational diffusion of the probe and spin labels of different length and flexibility, attached to HSA, on the viscosity of the solution, the degree of association of the protein molecules and the temperature of the sample was investigated. The effective energy and entropy parameters of the rotational diffusion of the probe and labels were determined. The mobility of radicals packed into HSA, in contrast to a freer radical, does not depend on the properties of the solvent or the movement of the protein globule as a whole, but apparently reflects local movements of the protein matrix. On the basis of the experimental and literature data a conclusion was made about the nature of the dynamic properties of the protein.