INTRAMOLECULAR SINGLET EXCITATION TRANSFER . APPLICATIONS TO POLYPEPTIDES

A critical examination of the conditions under which the formalism of the Förster singlet energy-transfer theory may be used to determine the donor-acceptor separation from the experimental energy-transfer efficiency is presented. In particular, the importance of multipole transitions, exchange interaction, “before-relaxation” transfer, and translational and rotational diffusion and the useful range of distances are examined. The overlap integrals and Förster distances for transfer between aromatic amino acids are evaluated from experimental absorption and fluorescence data for various environments and temperatures. The usefulness and limitations of energy-transfer experiments in the determination of intramolecular distances in polypeptides are discussed. © 1969, American Chemical Society. All rights reserved.