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Oxyleghemoglobin scavenges nitrogen monoxide and peroxynitrite: a possible role in functioning nodules?

Herold, Susanna ; Puppo, Alain

In: JBIC Journal of Biological Inorganic Chemistry, 2005, vol. 10, no. 8, p. 935-945

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    Titre
    • Oxyleghemoglobin scavenges nitrogen monoxide and peroxynitrite: a possible role in functioning nodules?
    Auteur
    • Herold, Susanna. Laboratorium für Anorganische Chemie, Eidgenössische Technische Hochschule, ETH Hönggerberg, 8093, Zürich, Switzerland
    • Puppo, Alain. UMR CNRS-UNSA-INRA IPMSV, 400, Route des Chappes, BP167, 06903, Sophia-Antipolis Cedex, France
    Type de document
    • Postprint
    Langue
    • Anglais
    Publié dans
    • JBIC Journal of Biological Inorganic Chemistry, 2005, vol. 10, no. 8, p. 935-945. Springer-Verlag
    Autre version électronique
    Identifiant OAI-PMH
    • oai:doc.rero.ch:315935
    Summary
    It has been demonstrated that the NO• produced by nitric oxide synthase or by the reduction of nitrite by nitrate reductase plays an important role in plants' defense against microbial pathogens. The detection of nitrosyl Lb in nodules strongly suggests that NO• is also formed in functional nodules. Moreover, NO• may react with superoxide (which has been shown to be produced in nodules by various processes), leading to the formation of peroxynitrite. We have determined the second-order rate constants of the reactions of soybean oxyleghemoglobin with nitrogen monoxide and peroxynitrite. At pH 7.3 and 20°C, the values are on the order of 108 and 104M−1s−1, respectively. In the presence of physiological amounts of CO2 (1.2mM), the second-order rate constant of the reaction of oxyleghemoglobin peroxynitrite is even larger (105M−1s−1). The results presented here clearly show that oxyleghemoglobin is able to scavenge any NO• and peroxynitrite formed in functional nodules. This may help to stop NO• triggering a plant defense reaction