Nitrate reductase (NAD[P]H) is expressed in variety of organisms including bacteria, fungi, algae, and higher plants which have capacity to use nitrate as their sole source of nitrogen.Experimental studies show that nitrate reductase (NAD[P]H) is 180,000Daltons.
Nitrate Reductase (NAD[P]H) catalyzes the reduction of nitrate to nitrite. In addition, it also catalyzes the reduction of NADPH-cytochrome c, FADH2-nitrate. Nitrate reductase also has reduced methyl viologen-nitrate reductase activities.