Fluorescence Quenching, Lifetimes, and Fluorophore Solvent Accessibility

The influence of the excited-state lifetime of a fluorophore on its susceptibility to collisional quenching is discussed. In the case of cytochrome c, FRET to the heme moiety strongly reduces the tryptophan fluorescence lifetime. This should be taken into account to correctly evaluate the tryptophan solvent accessibility from acrylamide quenching experiments.