In vitro Nitrate Reductase Activity Assay of Mycolicibacterium smegmatis Crude Extract.

Nitrate is one of the major inorganic nitrogen sources for microorganisms. Many bacterial and archaeal lineages can express cytoplasmic assimilatory nitrate reductase (NAS), which catalyzes the rate-limiting reduction of nitrate to nitrite in the nitrate assimilation pathway. Here, we present a detailed protocol for measuring in vitro nitrate reductase (NaR) activity of NAS enzymes from Mycolicibacterium smegmatis crude extract using both physiological and non-physiological electron donors.