Direct detection of radicals in intact soybean nodules: presence of nitric oxide-leghemoglobin complexes
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Direct detection of radicals in intact soybean nodules : presence of nitric oxide-leghemoglobin complexes. / Mathieu, C; Moreau, S; Frendo, P; Puppo, A; Davies, Michael Jonathan.
In: Free Radical Biology & Medicine, Vol. 24, No. 7-8, 1998, p. 1242-9.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - Direct detection of radicals in intact soybean nodules
T2 - presence of nitric oxide-leghemoglobin complexes
AU - Mathieu, C
AU - Moreau, S
AU - Frendo, P
AU - Puppo, A
AU - Davies, Michael Jonathan
PY - 1998
Y1 - 1998
N2 - Electron paramagnetic resonance spectroscopy has been employed to examine the nature of the metal ions and radicals present in intact root nodules of soybean plants grown in the absence of nitrate. The spectra obtained from nodules of different ages using this non-invasive technique show dramatic differences, suggesting that there are both qualitative and quantitative changes in the metal ion and radical species present. A major component of the spectra obtained from young nodules is assigned to a complex (Lb-NO) of nitric oxide (NO.) with the heme protein leghemoglobin (Lb). This Lb-NO species, which has not been previously detected in intact root nodules of plants grown in the absence of nitrate, is thought to be formed by reaction of nitric oxide with iron(II) leghemoglobin. The nitric oxide may be generated from arginine via a nitric oxide synthase-like activity present in the nodules of the soybean plants, in a manner analogous to that recently described for Lupinus albus. This Lb-NO complex is present at lower concentrations in older nodules, and is almost completely absent from senescent nodules. Exposure of young and mature nodules to oxidant stress, in the form of hydrogen peroxide, results in changes in the EPR spectra, with the loss of the signals from the Lb-NO complex and appearance of absorptions similar to those from untreated senescent nodules. These results suggest that there are characteristic changes in both the metal ion complexes and radicals present in intact root nodules of different ages, and support the theory that nitric oxide and other radicals play a significant role in determining the nitrogen fixing activity of root nodules; the modulatory activity of NO. may involve regulation of gene activity.
AB - Electron paramagnetic resonance spectroscopy has been employed to examine the nature of the metal ions and radicals present in intact root nodules of soybean plants grown in the absence of nitrate. The spectra obtained from nodules of different ages using this non-invasive technique show dramatic differences, suggesting that there are both qualitative and quantitative changes in the metal ion and radical species present. A major component of the spectra obtained from young nodules is assigned to a complex (Lb-NO) of nitric oxide (NO.) with the heme protein leghemoglobin (Lb). This Lb-NO species, which has not been previously detected in intact root nodules of plants grown in the absence of nitrate, is thought to be formed by reaction of nitric oxide with iron(II) leghemoglobin. The nitric oxide may be generated from arginine via a nitric oxide synthase-like activity present in the nodules of the soybean plants, in a manner analogous to that recently described for Lupinus albus. This Lb-NO complex is present at lower concentrations in older nodules, and is almost completely absent from senescent nodules. Exposure of young and mature nodules to oxidant stress, in the form of hydrogen peroxide, results in changes in the EPR spectra, with the loss of the signals from the Lb-NO complex and appearance of absorptions similar to those from untreated senescent nodules. These results suggest that there are characteristic changes in both the metal ion complexes and radicals present in intact root nodules of different ages, and support the theory that nitric oxide and other radicals play a significant role in determining the nitrogen fixing activity of root nodules; the modulatory activity of NO. may involve regulation of gene activity.
KW - Electron Spin Resonance Spectroscopy
KW - Free Radicals
KW - Hydrogen Peroxide
KW - Leghemoglobin
KW - Nitric Oxide
KW - Oxidative Stress
KW - Plant Roots
KW - Soybeans
M3 - Journal article
C2 - 9626580
VL - 24
SP - 1242
EP - 1249
JO - Free Radical Biology & Medicine
JF - Free Radical Biology & Medicine
SN - 0891-5849
IS - 7-8
ER -
ID: 138284291