PMID: 11607104Sep 1, 1990Paper

Enzymatic and nonenzymatic mechanisms for ferric leghemoglobin reduction in legume root nodules

Proceedings of the National Academy of Sciences of the United States of America
M Becana, R V Klucas

Abstract

Evidence is presented for the operation in nodules of at least four systems for restoring functional ferrous leghemoglobin (LB2+) from its inactive, ferric form. (i) Reduction of ferric leghemoglobin (LB3+) by a reductase. The enzyme is a flavoprotein of 100 kDa with two equally sized subunits andexhibits a Km of 9 microM for soybean LB3+ component a and a Km of 51 microM for NADH. NADPH is only 30% (initial velocities) as effective as NADH. LB3+ reductase converts 215 nmol of LB3+ to LB2+.CO (or Lb2+.O2) per mg of protein per min and does not require an exogenous electron carrier. The enzyme shows similar affinity for soybean, bean, and cowpea LB3+, but different Vmax values. The reductase is inactive with LB3+ is bound to nicotinate or NO2-. (ii) Direct reduction of LB3+ by NAD(P)H, ascorbate, and cysteine. Reduction by NAD(P)H is greatly stimulated by trace amounts of metals such as Mn2+. (iii) Reduction of Lb3+ by the flow of electrons from NAD(P)H to free flavins to LB3+. The reaction does not occur via O2.- or H2O2, and thus NAD(P)H-reduced flavins can directly reduce LB3+. The efficiency of the reaction follows the order riboflavin > FMN > FAD. (iv) Reduction of LB3+ by an unknown compound, B, of nodules. B has a molecul...Continue Reading

References

Jul 1, 1978·Journal of Agricultural and Food Chemistry·R Saetre, D L Rabenstein
Apr 8, 1987·Biochimica Et Biophysica Acta·L L Saari, R V Klucas
Mar 30, 1972·Biochimica Et Biophysica Acta·C Koizumi, W D Brown
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Jun 1, 1986·Proceedings of the National Academy of Sciences of the United States of America·D A DaltonH J Evans
Apr 1, 1984·Plant Physiology·K K Lee, R V Klucas

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Citations

Oct 1, 1992·Proceedings of the National Academy of Sciences of the United States of America·M Becana, R V Klucas
Jul 31, 2012·Journal of Plant Physiology·Aaron C AsensioJose Fernando Moran
Jun 2, 2007·Gene·Verónica Garrocho-VillegasRaúl Arredondo-Peter
Jan 1, 1992·Archives of Biochemistry and Biophysics·D A DaltonM Robbins
Feb 6, 2015·F1000Research·Raúl Arredondo-PeterGautam Sarath
Feb 6, 2015·F1000Research·Raúl Arredondo-PeterGautam Sarath
Jan 22, 2020·The New Phytologist·Manuel BecanaMark S Hargrove
May 23, 2020·The New Phytologist·Estíbaliz LarrainzarManuel Becana
Jun 1, 2010·The Journal of Biological Chemistry·Anne M GardnerPaul R Gardner
Jan 12, 2021·International Journal of Biological Macromolecules·Manish ShandilyaSuman Kundu
Oct 1, 1997·The New Phytologist·Kristina UlrichWolfgang Seyfarth

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