MECHANISM OF TRYPTOPHAN FLUORESCENCE QUENCHING

我们检查了时间分辨和稳态荧光

We examined the time-resolved and steady-state fluorescence quenching of N-acetyl-L-tryptophanamide. (NATA) by acrylamide and iodide, over a range of viscosities in propylene glycol. The quenching of NATA by acrylamide and iodide results in heterogeneity of the intensity decay which increases with the quencher concentration. We attribute the complex decay of NATA to transient effects in diffusion and the nature of the fluorophore-quencher interaction. Consideration of both the frequency-domain and steady-state data demonstrate that the quenching rate depends exponentially on the fluorophore-quencher distance, indicating the validity of a model which include a quenching constant which depend exponentially on distance. Such data on the distance dependence of quenching is important for understanding quenching of native proteins.