The NWLSS™ Nitric Oxide Enzymatic Assay kit is a system for measurement of nitric oxide as total nitrate and total nitrite in biological samples.
Nitric Oxide (NO) is a biologically relevant free radical and cell signaling molecule. In normal cellular physiology it was originally characterized as an endothelial relaxation factor (EDRF) and is most commonly associated with its role in regulation of vasodilation. From a pathogenic standpoint the free radical nitric oxide (NO•) is known to combine with superoxide (O2•) to form peroxynitrite (ONOO-) which is a potent oxidant. Since ONOO– (NO3-) is essentially an unstable isomer of nitrate, it can react with tyrosine residues in proteins to create nitrotyrosine, a biomarker of oxidative mediated modification of proteins.
Nitric oxide degrades rapidly to nitrate (NO3) and nitrite (NO2) in aqueous biological systems. When NO3 is reduced to NO2 measurement of nitrite provides a simple, indirect means to quantify nitric oxide produced in a wide array of experimental model systems.
The test method is based on measurement of total sample nitrites using Griess Reagent. Since Griess reagent does not detect nitrate NO3, this kit employs nitrate reductase for reduction of nitrate to nitrite (Fig. 1). Using purified plant nitrate reductase with NADH helps prevent NADPH interference with the Griess reaction as has been previously reported.
View Assay Protocol
Quantifying nitric oxide (NO) in biological samples.
Plasma, cell lystaes, tissue homogenates
Nitrites or total nitrate & nitrite after nitrate reduction.
1 pmol/mL or 1µM in the assay
|Storage and Stability:||
9 months from date of manufacture when stored at 2-8C
Microplate (96 well clear, low binding, flatbottom) |
MOPS Buffer (Sample Dilution Buffer)
Nitrate Standard (500 µM KNO3)
Nitrate Reductase (Lyophilized)
Nitrate Reductase Buffer
Reagent A: (Sulfanilamide (p-Aminobenzenesulfonamide) in 3N HCl)
Reagent B: (N-(1-Naphthyl) ethylenediamine dihydrochloride in deionized H2O)