ON THE ORIGIN OF NONEXPONENTIAL FLUORESCENCE DECAY IN TRYPTOPHAN AND ITS DERIVATIVES

The nonexponential fluorescence decay of tryptophan and its derivatives is discussed in terms of a simple model based on conformers about the Ca-CB bond and the relative rates of charge transfer from indole to various electrophiles. Accurate predictions concerning the relative fluorescence lifetimes and the form of the fluorescence decay law are made for tryptophan and 17 of its derivatives, including three new derivatives synthesized specifically to test the model.