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Article Addendum
Reactive Nitrogen Species-Dependent Effects on Soybean Chloroplasts
Susana Puntarulo, Sebastián Jasid and Marcela Simontacchi
volume 2 | issue 2
march/april 2007Pages: 96 - 98
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Nitric oxide (NO) generation by soybean (Glycine max, var ADM 4800) chloroplasts was studied by electron paramagnetic resonance (EPR) spin-trapping technique1. Both nitrite and L-arginine (arg) are the required substrates for enzymatic activities considered as possible sources of NO in plants. Soybean chloroplasts showed a NO production of 3.2 ± 0.2 nmol min-1 mg-1 protein in the presence of 1 mM NaNO2. Chloroplasts incubated with 1 mM arg showed a NO production of 0.76 ± 0.04 nmol min-1 mg-1 protein. This production was inhibited when chloroplasts were incubated in presence of NOS-inhibitors L-NAME and L-NNA. In vitro exposure of chloroplasts to a NO-donor (GSNO) decreased both ascorbyl radical content and the activity of ascorbate peroxidase, without modification of the total ascorbate content. Exposure of the isolated chloroplasts to a NO-donor decreased lipid radical content in membranes, however, incubation in the presence of 25 μM peroxynitrite (ONOO-) led to an increase in lipid-derived radicals (34%). The effect of ONOO- on protein oxidation was determined by western blotting, showing an increase in carbonyl content either in stroma or thylakoid proteins as compared to control. Taken as a whole, NO seems to be an endogenous metabolite in soybean chloroplasts and reactive nitrogen species could exert either antioxidant or prooxidant effects on chloroplasts, since both a decreased lipid radical content in membranes and a decrease in the activity of ascorbate peroxidase were observed after exposure to a NO donor.
Authors
Susana Puntarulo
University of Buenos Aires, Buenos Aires, Argentina
Sebastián Jasid
University of Buenos Aires, Buenos Aires, Argentina
Marcela Simontacchi
University of Buenos Aires, Buenos Aires, Argentina
We now provide open access to journal articles published online for one year or more. This article may be downloaded at the following link:
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