Kinetics of Stacking Interactions in Flavin Adenine Dinucleotide From Time‐resolved Flavin Fluorescence

The time dependence of the fluorescence of flavin adenine dinucleotide (FAD) was measured with a subnanosecond‐resolving fluorometer. In contrast to the fluorescence decay of FMN, the decay of FAD was proved to be nonexponential. The time‐dependent fluorescence of FAD can be interpreted by assuming an equilibrium between closed and open conformers in the ground state. The rate constant for folding in the excited state and the fluorescence lifetime of the intramolecular complex could be evaluated from analysis of the observed fluorescence decay. The results on FAD were compared to those on NADH obtained earlier.