Ultrafast Fluorescence Quenching Dynamics of Flavin Chromophores in Protein Nanospace

• DOI: 10.1021/jp982583t
• Publication Date: 2002-07-26T05:28:13Z
• Authors: Noboru Mataga; Haik Chosrowjan; Yutaka Shibata; Fumio Tanaka
• Keywords: 01 natural sciences; 0104 chemical sciences

We have studied excited-state dynamics of “nonfluorescent” flavoproteins by means of the femtosecond fluorescence up-conversion method. We have interpreted the ultrafast fluorescence quenching mechanisms of these flavoproteins as due to the ultrafast electron transfer or electron transfer followed by proton-transfer interactions between excited flavin chromophore and nearby tryptophan and tyrosine residues placed in the protein nanospace, on the basis of their X-ray structures. Comparisons of fluorescence time profiles and spectral characteristics of flavin chromophores in solutions with those in protein environments have suggested the existence of extremely fast Franck−Condon → fluorescent state relaxations specific to the protein environments. These results of the ultrafast fluorescence dynamics studies on the nonfluorescent flavoproteins have many features in common with other photobiologically important proteins.