Can nitric oxide be spin trapped by nitrone and nitroso compounds?

Area of Science:

• Biochemistry
• Molecular Biology
• Free Radical Chemistry

Background:

• Nitric oxide (NO) is a crucial biological free radical with diverse roles.
• Accurate detection of NO is essential for understanding its biological functions.
• Electron spin resonance (ESR) with spin traps is a common NO detection method.

Purpose of the Study:

• To evaluate the effectiveness of current spin traps for detecting NO generated by nitric oxide synthase (NOS).
• To investigate potential interferences between spin traps and NOS activity.
• To identify limitations of existing spin-trapping techniques for biological NO studies.

Main Methods:

• Electron spin resonance (ESR) spectroscopy was employed.
• Studies utilized nitric oxide synthase (NOS) enzyme systems.
• Various nitrone and nitroso spin traps, including 3,5-dibromo-4-nitrosobenzenesulfonic acid (DBNBS), were tested.
• Experiments involved authentic NO and isotopically labeled 15NO.

Main Results:

• NO generated directly from NOS could not be detected using standard ESR spin-trapping methods.
• The spin trap DBNBS was found to inhibit NO production by NOS.
• ESR spectra previously attributed to NO spin adducts were identified as artifactual, particularly when using N-hydroxylamines.

Conclusions:

• Existing spin traps are inadequate for accurately detecting NO produced by NOS.
• The inhibitory effects of some spin traps on NOS and the generation of artifactual signals compromise their utility.
• Development of novel, effective spin traps is required for reliable biological NO detection.