Enzymology of ferric chelate reduction at the root plasma membrane

Abstract Our research has focused on the characterization and purification of plasma membrane reductases of root cells that are involved in ferric chelate reduction in the rhizosphere of “Fe‐efficient”; tomato (Lycopersicon esculentum Mill). Fe chelate reductase activity in plasma membranes from Fe‐deficient plants exhibited Michaells‐Menten kinetics with regard to the substrate Fe3+ citrate. The kinetic data, as well as sensitivity of Fe chelate reduction to the protease trypsin, confirmed the essential enzymatic nature of the tomato root plasma membrane Fe chelate reductase. Differential enzyme rates obtained upon altering the sequence of addition of reactants in vitro suggested that the root plasma membrane Fe chelate reductase may require an ordered substrate binding mechanism for optimal activity. Partial inhibition of enzyme activity by catalase added to reaction mixtures suggested some participation by hydrogen peroxide to Fe chelate reduction in vitro. Electrophoretic separation of proteins from t...

[1]  M. Holden,et al.  Fe-Chelate Reductase Activity of Plasma Membranes Isolated from Tomato (Lycopersicon esculentum Mill.) Roots : Comparison of Enzymes from Fe-Deficient and Fe-Sufficient Roots. , 1991, Plant physiology.

[2]  L. Kochian,et al.  Does Iron Deficiency in Pisum sativum Enhance the Activity of the Root Plasmalemma Iron Transport Protein? , 1990, Plant physiology.

[3]  P. Kuiper,et al.  Plasma membrane‐bound NADH : Fe3+‐EDTA reductase and iron deficiency in tomato (Lycopersicon esculentum) - Is there a Turbo reductase? , 1990 .

[4]  W. Schmidt,et al.  Fe-EDTA Reduction in Roots of Plantago lanceolata by a NADH-dependent Plasma Membrane-bound Redox System , 1990 .

[5]  A. Vianello,et al.  Hydrogen peroxide formation and iron ion oxidoreduction linked to NADH oxidation in radish plasmalemma vesicles. , 1990, Biochimica et biophysica acta.

[6]  R. Chaney,et al.  Iron-Stress Induced Redox Activity in Tomato (Lycopersicum esculentum Mill.) Is Localized on the Plasma Membrane. , 1989, Plant physiology.

[7]  W. Brüggemann,et al.  NADH‐dependent Fe3+EDTA and oxygen reduction by plasma membrane vesicles from barley roots , 1989 .

[8]  D. Luster,et al.  Characterization and partial purification of multiple electron transport activities in plasma membranes from maize (Zea mays) roots , 1988 .

[9]  H. Bienfait.  Mechanisms in Fe-efficiency reactions of higher plants , 1988 .

[10]  C. Larsson,et al.  NAD(P)H oxidase and peroxidase activities in purified plasma membranes from cauliflower inflorescences , 1987 .

[11]  H. Marschner,et al.  Involvement of superoxide radical in extracellular ferric reduction by iron-deficient bean roots. , 1987, Plant physiology.

[12]  V. Römheld,et al.  Different strategies in higher plants in mobilization and uptake of iron , 1986 .

[13]  R. Hertel,et al.  Kinetic characterization of reduced pyridine nucleotide dehydrogenases (duroquinone-dependent) in cucurbita microsomes. , 1986, Plant physiology.

[14]  V. Römheld,et al.  Localization and capacity of proton pumps in roots of intact sunflower plants. , 1984, Plant physiology.

[15]  R. Chaney,et al.  Obligatory reduction of ferric chelates in iron uptake by soybeans. , 1972, Plant physiology.

[16]  U. K. Laemmli,et al.  Cleavage of Structural Proteins during the Assembly of the Head of Bacteriophage T4 , 1970, Nature.