Emission Anisotropy of Fluorescein Covalently Linked to Oligonucleotides

Rotational depolarization of fluorescence from fluorescein covalently linked to oligonucleotides was studied. Fluorescence anisotropy of two nucleic acids was measured as a function of the temperature-to-viscosity ratio in buffer solutions with various glycerin concentrations. It was shown that the experimental results could be satisfactorily explained by a diffusion model of an elongated molecular top with internal rotation. It was found that the coefficient of internal rotational diffusion in all instances was 1.5–2 times greater than that for rotation around the oligonucleotide axis.