Spectral characteristics of fluctuations in globular and red cell membrane proteins

The spectrum of the fluctuations of various dynamic properties of proteins in solutions and cell membranes revealed 1/f(alpha) noise characteristics. The value of the power law coefficient ct varied between 0.66 and 1.02. Generally a value of alpha approximate to 1 was characteristic for isolated proteins in solutions whereas alpha<1 was characteristic for membrane proteins. Perturbation of proteins by proteolysis or by the lipid bilayer attack with a detergent was sensed as a lower value of or. Return maps of the fluctuations further revealed qualitative differences among the various types of sample. It is suggested that the spectral characteristics of the fluctuations are sensitive to the type of sample and its condition.