Latent nitrate reductase activity is associated with the plasma membrane of corn roots

• Published in: Planta 1989, Vol.177 (4), p.470-475
• Main Authors: Ward, M.R. (California Univ., Davis (USA). Plant Growth Lab.), Grimes, H.D, Huffaker, R.C
• Format: Article
• Language: English
• Subjects: ACTIVIDAD ENZIMATICA; ACTIVITE ENZYMATIQUE; Adenosine triphosphatases; Adenosine Triphosphatases - analysis; Adenosine Triphosphatases - drug effects; Adenosine Triphosphatases - physiology; Barley; Biological and medical sciences; Cell Membrane - enzymology; Cell Membrane - ultrastructure; CELL MEMBRANES; Corn; Cytosol - enzymology; Enzymaktivitaet; Enzymes; ENZYMIC ACTIVITY; Fundamental and applied biological sciences. Psychology; Man/System Technology And Life Support; MEMBRANAS CELULARES; MEMBRANE CELLULAIRE; Membrane Proteins - analysis; Membrane Proteins - drug effects; Membrane Proteins - physiology; Metabolism; Microsomes; Microsomes - enzymology; Nitrate Reductase; Nitrate Reductases - analysis; Nitrate Reductases - drug effects; Nitrate Reductases - physiology; Nitrates; Nitrogen metabolism; Octoxynol - pharmacology; Plant cells; Plant physiology and development; Plant roots; Plant Roots - cytology; Plant Roots - enzymology; Plants; Plasmamembran; RACINE; RAICES; ROOTS; Sodium Chloride - pharmacology; Solubility; Space life sciences; Surface-Active Agents - pharmacology; Wurzel; Zea; ZEA MAYS; Zea mays - enzymology; Zea mays - ultrastructure
• ISSN: 0032-0935; 1432-2048
• DOI: 10.1007/BF00392614

Latent nitrate reductase activity (NRA) was detected in corn (Zea mays L., Golden Jubilee) root microsome fractions. Microsome-associated NRA was stimulated up to 20-fold by Triton X-100 (octylphenoxy polyethoxyethanol) whereas soluble NRA was only increased up to 1.2-fold. Microsome-associated NRA represented up to 19% of the total root NRA. Analysis of microsomal fractions by aqueous two-phase partitioning showed that the membrane-associated NRA was localized in the second upper phase (U2). Analysis with marker enzymes indicated that the U2 fraction was plasma membrane (PM). The PM-associated NRA was not removed by washing vesicles with up to 1.0 M NACl but was solubilized from the PM with 0.05% Triton X-100. In contrast, vanadata-sensitive ATPase activity was not solubilized from the PM by treatment with 0.1% Triton X-100. The results show that a protein capable of reducing nitrate is embedded in the hydrophobic region of the PM of corn roots.