Energy transfer to a proton-transfer fluorescence probe: Tryptophan to a flavonol in human serum albumin

摘要

A protein fluorescence probe system, cou- pling excited-state intermolecular Forster energy transfer and intramolecular proton transfer (PT), is presented. As an energy donor for this system, we used tryptophan, which transfers its excitation energy to 3-hydroxyflavone (3-HF) as a flavonol prototype, an acceptor exhibiting excited-state intramolecular PT. We demonstrate such a coupling in human serum albumin-3-HF complexes, excited via the single intrin- sic tryptophan (Trp-214).