Fluorophore-labeled S-nitrosothiols.

Area of Science:

• Chemical Biology
• Organic Synthesis
• Biophysical Chemistry

Background:

• S-nitrosothiols (SNOs) are crucial signaling molecules involved in various physiological processes.
• Developing sensitive and specific probes for detecting SNOs and their associated nitric oxide (NO) transfer is essential for biological research.

Purpose of the Study:

• To synthesize and characterize novel fluorophore-labeled S-nitrosothiols for enhanced fluorescence detection.
• To investigate the mechanism of fluorescence enhancement upon NO group removal.
• To evaluate the utility of these probes in studying S-nitrosothiol/thiol transnitrosation kinetics and NO transfer in cellular environments.

Main Methods:

• Synthesis of dansyl-labeled S-nitrosothiols with varying alkyl linkers.
• Evaluation of fluorescence enhancement via transnitrosation and photolysis.
• Ab initio density functional theory (DFT) calculations to understand electronic interactions.
• Kinetic studies of S-nitrosothiol/thiol transnitrosation.
• Application as fluorescence probes in human umbilical vein endothelial cells.

Main Results:

• Dansyl-labeled S-nitrosothiols exhibited up to 30-fold fluorescence enhancement upon NO group removal.
• Fluorescence enhancement is attributed to intramolecular energy transfer from the dansyl fluorophore to the SNO moiety.
• DFT calculations revealed favorable overlap and stabilizing interactions between the SNO group and dansyl ring, influenced by linker length and sulfonamide rigidity.
• The probe successfully monitored transnitrosation kinetics and NO transfer in endothelial cells.

Conclusions:

• Novel fluorophore-labeled S-nitrosothiols serve as effective fluorescent probes for NO detection.
• The design strategy, involving intramolecular energy transfer and tunable linker properties, enhances probe sensitivity.
• These probes offer a valuable tool for investigating NO signaling pathways and S-nitrosothiol chemistry in biological systems.