Plasmalemma redox activity in the diatom Thalassiosira is competitively inhibited by antiserum prepared against algal nitrate reductase (NR), and fluorescent labeling experiments reveal the binding of NR antiserum to the cell surface. Furthermore, the external electron acceptor Cu bathophenanthroline disulfonate causes immediate inhibition of intracellular primary amine production. A model is p...

ASSIMILATORY NITRATE REDUCTASE (NADH: nitrate oxidoreductase, EC 1.6.6.1) from Chlorella vulgaris has been purified to electrophoretic homogeneity with an overall yield of 60% by a procedure that utilizes blue dextran-agarose as an affinity column. Nitrate reductase binds to blue dextran and is not eluted in the presence of high ionic strength buffer but is rapidly eluted in the presence of mum...

Nitrate assimilation in many plants, algae, yeasts and bacteria is mediated by two enzymes, nitrate reductase (EC 1.6.6.2) and nitrite reductase (EC 1.7.7.1). They catalyse the stepwise reduction of nitrate to nitrite and nitrite to ammonia respectively. The nitrite reductase from an industrially important yeast, Candida utilis, has been purified to homogeneity. Purified nitrite reductase is a ...

CMldmyuOnas rihardii cells, growning photoautotropbical under air, excreted to the culture medium much higher amounts of N02 and NH4 I under ble than under red fight. Under shmilar conditions, but with N02as the only nitrogen source, the cells consumed NO2 and excreted NH4, at shilar rates under blue and red light. In the presence of N03and air with 2% CO2 (v/v), no excretion of NOand NH1+ occu...

Suspension cultures of Paul's Scarlet rose were grown in two defined media which differed only in their inorganic nitrogen content. Both possessed equal amounts of NO(3) (+) (24 mm), but differed in that NH(4) (+) (0.91 mm) was present in control medium; whereas, no NH(4) (+) was present in the test medium. A comparison of fresh weight increases over a 14-day growth period showed that NH(4) (+)...

l-Canavanine inhibits the appearance of nitrate reductase (NADH-nitrate oxidoreductase, EC 1.6.6.1) in both root tips and mature root sections of corn (Zea mays L.). Ten-fold more canavanine was required to cause a 50% reduction in the level of nitrate reductase activity (NRA) in root tips than in mature root sections. For example with one particular batch of seeds 500 mum canavanine was effect...

The YNT1 gene encoding the nitrate transporter in the yeast Hansenula polymorpha is clustered with genes YNI1 and YNR1 encoding nitrite reductase and nitrate reductase, and its disruption causes inability to grow in nitrate M. Dolores PE; REZ, Celedonio GONZA; LEZ, Julio A; VILA, Ne! lida BRITO and Jose! M. SIVERIO* Departamento de Bioquı!mica y Biologı!a Molecular, Universidad de La Laguna, E-...

Nitrate reductase induction by nitrate and repression by NH,+ has been studied extensively in the simple eukaryote Aspergillus nidulans (Pateman & Cove, 1967; Cove & Pateman, 1968). Wild-type cells grown on minimal medium, with 20m~-NaNO~ as the nitrogen source, rapidly lose nitrate reductase activity when transferred either to minimal medium without N (-N medium) or to minimal medium without C...

Barley seedlings grown in the dark with 10 mm KNO(3) have low levels of nitrate reductase activity even though large amounts of No(3) (-) accumulate in the leaves. When the leaves are excised and transferred to the light, there is an increase in nitrate reductase activity both in the presence and absence of exogenous NO(3) (-). When the leaves are transferred to a glucose solution (0.05 m) but ...

Molybdenum cofactor activity was found in the soluble fraction of cell-free extracts of Escherichia coli grown aerobically in media supplemented with molybdate. Cofactor was detected by its ability to complement the nitrate reductase-deficient mutant of Neurospora crossa, nit-1, resulting in the vitro formation of nitrate reductase activity. Acid treatment of E. coli extracts was not required f...