Effect of increasing concentrations of nonionic detergent Triton X-100 on solubilization and structure of rat liver and adipose plasma membranes.

The extent of solubilization and the structure of rat liver and adipose plasma membranes after treatment with nonionic detergent Triton X-100 were studied. The concentration of Triton X-100 varied from 0.005 to 0.050% (0.26-2.6 mg/mg membrane protein). The excimerization of the pyrene fluorescent probe and the relative vibronic band intensities in the pyrene monomer fluorescence spectrum were measured to evaluate the membrane lipid bilayer fluidity and polarity. The data on the aqueous pyrene fluorescence in the presence of Triton X-100 showed that formation of micellar aggregates occurred at detergent concentrations of over 0.015%. This value is a crucial factor in the detergent action on the membrane structure: both intensive extraction of plasma membrane proteins and fluidization of the lipid bilayer were observed only at Triton X-100 concentration over 0.015%. However, Triton X-100 did not exert any action on the polarity of the membrane hydrophobic regions.