Quantitative prediction of dye fluorescence quantum yields in proteins

Abstract

The application of a method previously developed by Callis et al. to predict the quantum yields of Trp fluorescence has been successfully applied to the fluorescence of fluorescein and flavins in proteins. The calculated lifetime range of 2 ps - 4 ns is in agreement with experiment. The fluctuations in the electron transfer rate are shown to be dictated by the fluctuations in the density of states. This is evident by the comparison of the fractional deviation of the interaction, density of states and the rate. Here the fluctuations in the density of states is an order of magnitude larger than the fluctuations in the interactions and is nearly the same as that of the kET fluctuations. This demonstrates that the fluorescence lifetime variability is controlled by the electrostatic environment and not the distance dependence of the interaction.