Practice question

Tryptophan fully exposed to water experiences maximal dipolar stabilization of its excited state. Solvent relaxation around excited indole lowers S1 energy, narrowing S1-S0 gap and shifting emission to about 350 to 355 nanometers. Buried residues in apolar core lack such stabilization, emitting near 308 to 335 nanometers. Tyrosine emits around 303 nanometers, distinct. Observing maximum near 350 nanometers therefore indicates surface, loop or unfolded region where water interacts freely. This wavelength criterion serves as benchmark for denaturation and solvent accessibility mapping.