Conformational Distributions Of Flexible Molecules From Steady State Fluorescence Energy Transfer

We demonstrate that distance distributions between two sites on flexible molecules can be recovered using steady state measurements of fluorescence energy transfer. The characteristic Forster distance (R°) for energy transfer was varied by collisional quenching of the donor, which decreases its quantum yield. The measured transfer efficiencies for each value of R. provide a different average of the distance distribution. The R.-dependent transfer efficiencies, when analyzed by non linear least- squares, were found to reliably determine the distance distribution, as shown by agreement with the frequency-domain method (Chem. Phys. Lett. 1987, 138:587-593).