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Free keywords:
*Luminescent Proteins/ch [Chemistry]; Luminescent Proteins/ge [Genetics]; Mutagenesis; *Photochemistry; Spectrometry, Fluorescence; Spectrophotometry, Ultraviolet; Support, Non-U.S. Gov't; Structural basis; Crystal structure; Single molecules; Spectroscopy; Microscopy; Behavior
Abstract:
We demonstrate by using low-temperature high-resolution spectroscopy that red-shifted mutants of green fluorescent protein are photo-interconverted among three conformations and are, therefore, not photostable "one-color" systems as previously believed. From our experiments we have further derived the energy-level schemes governing the interconversion among the three forms. These results have significant implications for the molecular and cell biological applications of the green fluorescent protein family; for example, in fluorescence resonant energy transfer experiments, a change in "color" on irradiation may not necessarily be due to energy transfer but can also arise from a photo-induced conversion between conformers of the excited species.
