Oxidation of hydroxylamines to NO by plant cells |
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Authors: | Stefan Rümer Jagadis Gupta Kapuganti Werner M Kaiser |
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Institution: | Julius-von-Sachs-Institut für Biowissenschaften; Würzburg, Germany |
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Abstract: | At least theoretically, plants may synthesize nitric oxide (NO) either by reduction of N in higher oxidations states, or by oxidation of more reduced N-compounds. The well established reductive pathway uses nitrite as a substrate, produced by cytosolic nitrate reductase. The only oxidative pathway described so far comprises nitric oxide synthase (NOS)-like activity, where guanidino-N from L-arginine is oxidized to NO. In our previous paper we have demonstrated yet another form of oxidative NO formation, whereby hydroxylamine (HA), but also the AOX-inhibitor salicylhydroxamate (SHAM) is oxidized to NO by tobacco suspension cells. Oxidation of HA to NO was also demonstrated in vitro by using ROS producing enzymes. Apparently superoxide radicals and/or hydrogen peroxide served as oxidants. Another unexpected observation pointed to a special role for superoxide dismutase in oxidative NO formation.Key words: hydroxylamine, nitric oxide, oxidative NO formation, reactive oxygen species, salicyl hydroxamate, superoxide dismutase |
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