Chemistry Letters, Vol.34, No.6, 766-767, 2005
A chemically modified green-fluorescent protein that responds to cleavage of an engineered disulphide bond by fluorescence resonance energy transfer (FRET)-based changes
The mixed disulfide of a Green-Fluorescent Protein with an Alexa 532 fluorescent label showed FRET, with quenching of the GFP emission. Reductive cleavage of this disulfide bond destroyed the FRET, giving a change in the ratios of fluorescence intensity at the wavelengths corresponding to the GFP and the Alexa dye. Cleavage by glutathione (second order rate constant at pH 7.4 was 1.18 +/- 0.02 x 10(2) M-1 min(-1)) was faster than for sodium cyanoborohydride.