6533b835fe1ef96bd129f36a

RESEARCH PRODUCT

Use of the red-edge excitation effect for investigation of dielectric interactions in biomembranes

subject

description

Dipole moments of the fluorescent probes 1-phenylnaphthylamine (1-AN) and 1-anilinonaphthalene-8-sulfonate (1,8-ANS) are measured using electro-optical absorption and emission methods. Dipole moments in the ground and excited states were measured in cyclohexane and dioxane. It is shown that the charge distributions in the 1-AN and 1,8-ANS molecules differ substantially. The spectral dependence of the electro-optical coefficients suggests that the absorption spectrum of 1,8-ANS is due to a superposition of (at least two) electronic transitions. It is found that spectra of 1-AN in erythocyte ghosts are inhomogeneously broadened. The above effect makes it possible to selectively excite probe molecules localized at different sites of a membrane. Dielectric interactions (described by the local dielectric constant) are investigated in human erythrocyte membranes. It is found that the dielectric constant of erythrocyte membranes varies from 6.79 ±0.8 to 17.6±3.5 depending on the excitation frequency and, therefore, on the localization of the probe.