New aza-boron-dipyrromethene compounds for single molecule fluorescence studies

SZALAI, A.M.; GIORDANO, L.; BARI, S.E.; SILBERSTEIN, S.; CAVASOTTO, CLAUDIO N.; ARAMENDÍA, P.F.

Santiago

Congreso; 25th Inter-American Photochemical Society Meeting; 2016

Corticotropin-releasing hormone (CRH) is a key peptide involved in neuroendocrine responseto stress. There is a widespread interest in understanding CRH type 1 receptor (CRHR1)molecular behavior, as it plays a primary role in regulatory mechanisms. Owing to the lackof reliable specific antibodies for CRHR1, studying its dynamics and cellular distribution byfluorescence microscopy requires a different labeling strategy. A set of novel fluorescentantagonists have been designed for this purpose. Based on non-fluorescent reportedantagonists and the crystal structure of CRHR1, a set of compounds based on an aza-borondipyrromethene (aza-BODIPY) core were chosen for a docking study. Aza-BODIPYs aresuitable for single molecule fluorescence microscopy (SMFM), due to their highphotostability and emission brightness3. Docking studies were performed using the Internal Coordinates Mechanics (ICM) software (MolSoft LLC, La Jolla, CA), and a flexible ligandrigid receptor approach. Compound 1 was chosen as the first compound to be synthesized. Itsprecursor, 2, has been successfully synthesized and its spectroscopic properties weremeasured. Compound 2 displays negative solvatochromism, for maxima normalizedspectra in methanol and dichloromethane. Emission quantum yield in these solvents is around0.80, with a lifetime of 3.9 ns.SMFM images of compound 2 in nanometer films in poly(methyl methacrylate) spin coatedon glass coverslips were obtained. Blinking and bleaching properties and their laser intensitypower law were studied. Results indicate that compound 2 is a promising dye for singlemolecule experiments.