Determination of nitrate and nitrite in biological samples using bacterial nitrate reductase coupled with the griess reaction

In this article we discuss methodology for quantitation of nitrite and nitrate, end products of the biological synthesis of nitric oxide from L-arginine. Both nitrite and nitrate can be measured, with accuracy to the low micromolar range, using bacterial nitrate reductase coupled to the Griess reaction. Methods for preparing nitrate reductases from Escherichia coli and Pseudomonas oleovorans are outlined. Details for using E. coli or P. oleovorans derived nitrate reductases and for performing the Griess reaction also are described.