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Design, Synthesis, and Characterization of Bis(7‑(N‑(2-morpholinoethyl)sulfamoyl)benzo[c][1,2,5]oxadiazol-5-yl)sulfane for Nonprotein Thiol Imaging in Lysosomes in Live Cells
journal contribution
posted on 2019-11-08, 22:43 authored by Yahya Alqahtani, Shenggang Wang, Yue Huang, Asim Najmi, Xiangming GuanThiols
are critical to cellular structures and functions. Disturbance
of cellular thiols has been found to affect cell functions and cause
various diseases. Intracellularly, thiols were found unevenly distributed
in subcellular organelles. Probes capable of detecting subcellular
thiol density in live cells are valuable tools in determining thiols’
roles at the subcellular level. The subcellular organelle lysosome
is the place where unwanted macromolecules are removed through degradation
by hydrolytic enzymes. The degradation also serves as a regulation
of a variety of cellular functions such as autophagy, endocytosis,
and phagocytosis to maintain cellular homeostasis. Thiols are found
to be involved in the lysosomal degradation process. A probe that
can detect lysosomal thiols in live cells will be a valuable tool
in unveiling the roles of thiols in lysosomes. We would like to report
bis(7-(N-(2-morpholinoethyl)sulfamoyl)benzo[c][1,2,5]-oxadiazol-5-yl)sulfane (BISMORX) as a thiol specific
fluorogenic agent for live cell nonprotein thiol (NPSH) imaging in
lysosomes through fluorescence microscopy. BISMORX itself shows no
fluorescence and reacts readily with a NPSH to form a fluorescent
thiol adduct with excitation and emission wavelengths of 380 and 540
nm, respectively. BISMORX does not react with compounds containing
nucleophilic functional groups other than thiols such as −OH,
−NH2, and −COOH. No reaction was observed
either when BISMORX was mixed with protein thiols. BISMORX was able
to image, quantify, and detect the change of NPSH in lysosomes in
live cells. A colocalization experiment with LysoTracker Red DND-99
confirmed that the thiols imaged by BISMORX were indeed lysosomal
thiols.