Practice question

Chemical denaturant guanidine hydrochloride disrupts hydrophobic core and hydrogen bonding, unfolding polypeptide and distancing tryptophan residues from internal quenchers like protonated histidine, cysteine disulfides, backbone amides and energy acceptors such as heme groups. While unfolding exposes tryptophan to water which slightly reduces quantum yield and red shifts emission, removal of efficient quenching contacts often dominates overall behavior, causing net increase in fluorescence intensity despite greater water exposure. This intensity rise upon denaturation illustrates interplay between solvent effects and specific intramolecular quenching in native folded structure.