Fig. 4.

Time scales of the dynamic processes involved. Indicated are the rotational correlation time of the donor chromophore (blue dashed line), the relaxation time of the autocorrelation function of the end-to-end distance fluctuations calculated from the simulations (green filled circles), and the fluorescence lifetime of the donor dye (red circles) as a function of the number of proline residues in the chain. The typical duration of a photon burst is ≈1 ms. (Left Inset) The end-to-end distance autocorrelation function for the polyproline 20-mer (green) fit to a single-exponential decay (black). (Right Inset) The anisotropy decay of the donor chromophore (blue) fit to a double-exponential decay (black). The faster component of the decay (0.3 ns), which contains 70% of the amplitude, was assigned to the rotational correlation time of the dye (48), and the slower component (0.8 ns) was assigned to the rotational correlation time of the entire molecule.