Resonance Energy Transfer in a Genetically Engineered Polypeptide Results in Unanticipated Fluorescence Intensity.
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.
['Seeley|Jason P|JP|', 'Cotlet|Mircea|M|', 'Eagleton|Aileen M|AM|', 'Higashiya|Seiichiro|S|', 'Welch|John T|JT|http://orcid.org/0000-0002-7434-141X']
D003374:Coumarins D031541:Fluorescence Resonance Energy Transfer D005456:Fluorescent Dyes D008301:Maleimides D008958:Models, Molecular D010455:Peptides D000072757:Protein Conformation, beta-Strand D017510:Protein Folding D014364:Tryptophan
energy transfer fluorescence peptides photophysics protein folding