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Resonance Energy Transfer in a Genetically Engineered Polypeptide Results in Unanticipated Fluorescence Intensity
Author(s) -
Seeley Jason P.,
Cotlet Mircea,
Eagleton Aileen M.,
Higashiya Seiichiro,
Welch John T.
Publication year - 2019
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201804470
Subject(s) - chromophore , fluorescence , chemistry , tryptophan , photochemistry , fluorescence in the life sciences , förster resonance energy transfer , acceptor , circular dichroism , folding (dsp implementation) , biophysics , crystallography , amino acid , biochemistry , optics , physics , electrical engineering , engineering , biology , condensed matter physics
Abstract The fluorescence intensity of a C‐terminal acceptor chromophore, N‐ (7‐dimethylamino‐4‐methyl coumarin (DACM), increased proportionally with 280 nm irradiation of an increasing number of donor tryptophan residues located on a β‐sheet forming polypeptide. The fluorescence intensity of the acceptor chromophore increased even as the length of the β‐sheet edge approached 256 Å, well beyond the Förster radius for the tryptophan–acceptor chromophore pair. The folding of the peptides under investigation was verified by circular dichroism (CD) and deep UV resonance Raman experiments. Control experiments showed that the enhancement of DACM fluorescence occurred concomitantly with peptide folding. In other control experiments, the DACM fluorescence intensity of the solutions of tryptophan and DACM did not show any enhancement of DACM fluorescence with increasing tryptophan concentrations. Formation of fibrillar aggregates of the substrate peptides prepared for the fluorescence studies was undetectable by thioflavin T (ThT) fluorescence.