Convenient colorimetric and fluorometric assays for S-nitrosothiols

Area of Science:

• Biochemistry
• Analytical Chemistry
• Spectroscopy

Background:

• S-nitrosothiols (RSNOs) are crucial signaling molecules involved in various physiological processes.
• Existing detection methods, primarily chemiluminescence, require specialized equipment not widely available.
• Development of accessible spectroscopic methods for RSNO quantitation is needed.

Purpose of the Study:

• To develop and validate novel colorimetric and fluorometric assays for S-nitrosothiol detection.
• To enable reliable quantitation of RSNOs using conventional UV-Vis and fluorescence spectroscopy.
• To provide sensitive and accessible methods for analyzing RSNOs and S-nitrosylated proteins.

Main Methods:

• Colorimetric detection involving the release of nitric oxide (NO) from RSNOs using HgCl2 or Cu(acetate)2, followed by reaction with oxygen and detection via UV-Vis spectroscopy (400-800 nm).
• Fluorometric detection utilizing 2,3-diaminonaphthalene as a scavenger for NO/O2 products, enabling sensitive detection of GSNO.
• Application of the fluorometric method for the quantitation of S-nitrosylated proteins.

Main Results:

• Developed colorimetric methods with linear responses for RSNOs in the presence of Hg(II) or Cu(II) ions.
• Achieved a sensitivity as low as 5 µM RSNO using HgCl2 in the colorimetric assay.
• Established a fluorometric method with a sensitivity of 50 nM for GSNO, and successfully quantified S-nitrosylated proteins.

Conclusions:

• The developed colorimetric and fluorometric methods provide accurate and sensitive quantitation of S-nitrosothiols.
• These assays utilize conventional spectroscopic techniques, making them accessible to most laboratories.
• The methods are suitable for determining low concentrations of S-nitrosothiols and S-nitrosylated proteins in biological systems.