Nitrate Reductase from Suspension Cultured Cells of Marchantia Polymorpha L.

Abstract

Summary Nitrate reductase from suspension cultured cells of a bryophyte, Marchantia polymorpha L., was purified to 550-fold by a procedure involving blue-Sepharose affinity chromatography. The purest enzyme used NADPH as an electron donor if FAD was added to the reaction mixture, but did not use NADH even in the presence of FAD. The specific activity of the purest enzyme was 3.9 μmoles nitrite produced/min/mg protein. The purest fraction possessed three associated activities; FAD dependent NADPH-cytochrome c reductase, FADH 2 - and MVH-nitrate reductase. A study of the effects of inhibitors on the three activities demonstrated that the NADPH-nitrate reductase consisted of two functional parts. The molecular weight of the intact enzyme determined by gel filtration was 220,000.