Highly Fluorescent Green Fluorescent Protein Chromophore Analogues Made by Decorating the Imidazolone Ring.
1. Departamento de Quimica Organica y Quimica Inorganica, Universidad de Alcala, Edificio de Farmacia, 28871, Alcala de Henares, Madrid (Spain). 2. Departamento de Quimica, Centro de Investigacion en Sintesis Quimica (CISQ), Universidad de La Rioja, Madre de Dios, 53, 26006, Logrono, La Rioja (Spain). 3. Departamento de Biologia de Sistemas, Universidad de Alcala, Edificio de Medicina, 28871, Alcala de Henares, Madrid (Spain). 4. Departamento de Quimica, Universidad Yachay Tech, Hacienda San Jose s/n, San Miguel de Urcuqui, 100119 (Ecuador).
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TD-DFT calculations; cell staining; fluorescence; imidazolone derivatives; proteins
The synthesis and photophysical behavior of an unexplored family of green fluorescent protein (GFP)-like chromophore analogues is reported. The compound (Z)-4-(4-hydroxybenzylidene)-1-propyl-2-(propylamino)-1H-imidazol-5(4 H)-one (p-HBDNI, 2 a) exhibits significantly enhanced fluorescence properties relative to the parent compound (Z)-5-(4-hydroxybenzylidene)-2,3-dimethyl-3,5-dihydro-4H-imidazol-4-one (p-HBDI, 1). p-HBDNI was considered as a model system and the photophysical properties of other novel 2-amino-3,5-dihydro-4H-imidazol-4-one derivatives were evaluated. Time-dependent DFT calculations were carried out to rationalize the results. The analogue AIDNI (2 c), in which the 4-hydroxybenzyl group of p-HBDNI was replaced by an azaindole group, showed improved photophysical properties and potential for cell staining. The uptake and intracellular distribution of 2 c in living cells was investigated by confocal microscopy imaging.