Electronic Excitation Energy Transfer between Molecules of Carbocyanine Dyes in Complexes with DNA: Distribution of Distances in Donor-Acceptor Pairs

摘要

Electronic excitation energy transfer (EEET) between molecules of carbocyanine dyes, which form noncovalent complexes with DNA, has been studied by steady-state and time-resolved technique. Three oxacarbocyanine dyes have been used as electronic excitation energy donors, and 3,3'-diethylthiacarbocyanine iodide has served as an acceptor dye. The fluorescence decay kinetics of the donors and its quenching by the acceptor in the presence of DNA were measured by picosecond spectrofluorometer. Monte-Carlo simulation of the fluorescence decay kinetic has been performed. An analysis of the kinetic dependences permitted obtaining the data on distribution of the distances in donor-acceptor pairs upon EEET, which have been compared with the results of the steady-state fluorescent experiments. The effect of the acceptor concentration on the parameters of distribution of its molecules in the quenching microphase has been revealed.