What happens to the fluorescence of tryptophan when it is in a polar environment?

In a polar environment, the fluorescence of tryptophan is red-shifted to longer wavelengths. This phenomenon occurs due to the interaction between the excited electronic states of tryptophan and the surrounding solvent molecules. When tryptophan is in a polar environment, the electrons of the molecule experience stabilization due to solvation interactions, causing a shift in the energy levels involved in the fluorescence. Specifically, the energy of the emitted light is lower (which corresponds to longer wavelengths) compared to tryptophan in non-polar environments.

Additionally, in a polar solvent, the energy levels of the excited state are stabilized more than those of the ground state, resulting in a redshift of the emitted light. This effect is crucial in biochemistry since it can influence how proteins containing tryptophan are studied using fluorescence spectroscopy, impacting how we measure interactions and conformational changes in proteins.