Biophysics

Molecular Cloaking

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Science  05 Sep 2008:
Vol. 321, Issue 5894, pp. 1273
DOI: 10.1126/science.321.5894.1273b

Natural products, such as latex rubber or betalactam antibiotics, have given rise to entire industries, and green fluorescent protein (GFP) has fought its way onto the list. A series of variants created in several laboratories have shifted the peak excitation and emission wavelengths (for multicolor imaging), improved the photostability (for time-lapse cinematography), and enhanced the quantum yields (lowering detection thresholds). Andresen et al. describe their latest entry—which has been christened Padron in recognition of its “reversed” behavior in comparison to its parent, Dronpa—and demonstrate how to implement multilabel, single-color imaging. Dronpa and its widely used descendant rsFastLime fluoresce when excited with blue light (488 nm), which also converts them from an “on” state to an “off” or nonfluorescent state, from which they can be switched on again by irradiation with ultraviolet (UV) light (405 nm). In contrast, Padron (differing at eight amino acid residues from Dronpa) is switched off by UV and on by blue light. As the emission of both proteins is centered at roughly 520 nm, and both exhibit very low off-state fluorescence, a single detection window can be used.— GJC

Nat. Biotechnol. 26, 10.1038/nbt.1493 (2008).

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