Purification and characterization of nitrate reductase from nodule cytosol of soybean plants

Abstract

Nodulated soybean (Glycine max [L.] Merr.) plants wereprotein showed a main band at 100 kDa on sodium dodecyl sulfate (SDS)-PAGE. The K m value for nitrate was 0.16 mM, grown in a nitrogen-free liquid culture medium prepared with and the highest activity was obtained at around pH 7.5. These distilled water. The cytosol fraction from root nodules showed characteristics are very similar to the inducible type of nitrate a significant level of NADH-dependent nitrate reductase activity, even when the root did not show activity. This nitrate reductase, previously purified from soybean leaves. The develreductase was purified by column chromatography and native opmental change in activity of this enzyme corresponded to polyacrylamide gel electrophoresis (PAGE). The purified that in nitrogenase activity.

Nitrogen stress and the expression of asparagine synthetase in roots and nodules of soybean (Glycine max)

“…The fact that the expression of SAS1 is apparently maintained in the nodule when the plants are given nitrate, a known inhibitor of N 2 fixation (Arrese‐Igor et al 1997, Streeter 1988), suggests that in this situation, nitrate assimilation either in the roots or in the nodules is responsible for SAS1 expression in the nodule. Reduction of nitrate and its subsequent assimilation is possible in the nodule itself because this tissue does possess nitrate reductase activity (Arrese‐Igor et al 1997, Kanayama et al 1999). Because AS expression in nodules appears to be dependent on N assimilation, but not on nitrate, it is possible that some product of N assimilation is responsible for AS expression.…”

Cytosolic Concentrations and Transmembrane Fluxes of NH4 +/NH3. An Evaluation of Recent Proposals

“…Furthermore, the extensively studied glycolytic enzymes have K m /[substrate] c ratios that vary from 0.02 to 333 (Fersht, 1985), and similar deviations of K m /[substrate] c from unity can be found for the enzymes nitrate reductase and pyruvate kinase. In the first case, K m /[NO 3 ] c can be as low as 0.01 (Lee and Clarkson, 1986;Siddiqi et al, 1991;Miller and Smith, 1992;Kanayama et al, 1999), whereas in the second, the ratio can be as low as 0.02 (Memon et al, 1985a(Memon et al, , 1985bWalker et al, 1996).…”

Involvement of nitric oxide in the inhibition of nitrogenase activity by nitrate in Lotus root nodules

“…In a NR-deficient pea mutant (Kaiser et al, 1997), the inhibition of nitrogenase activity by nitrate is partially suppressed. Thus, we focused on plant NR in the nodule cytosol (Kanayama et al, 1999;Kato et al, 2003).…”