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PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
2010-6-29
pubmed:abstractText
After SO(2) has entered leaves of spinach (Spinacia oleracea) through open stomata and been hydrated in the aqueous phase of cell walls, the sulfite formed can be oxidized to sulfate by an apoplastic peroxidase that is normally involved in phenol oxidation. The oxidation of sulfite is competitive with the oxidation of phenolics. During sulfite oxidation, the peroxidase is inhibited. In the absence of ascorbate, which is a normal constituent of the aqueous phase of the apoplast, peroxidative sulfite oxidation facilitates fast additional sulfite oxidation by a radical chain reaction. By scavenging radicals, ascorbate inhibits chain initiation and sulfite oxidation. Even after exposure of leaves to high concentrations of SO(2), which inhibited photosynthesis, the redox state of ascorbate remained almost unaltered in the apoplastic space of the leaves. It is concluded that the oxidative detoxification of SO(2) in the apoplast outside the cells is slow. Its rate depends on the rate of apoplastic hydrogen peroxide generation and on the steady-state apoplastic concentrations of phenolics and sulfite. The affinity of the peroxidase for phenolics is higher than that for sulfite.
pubmed:commentsCorrections
pubmed:language
eng
pubmed:journal
pubmed:status
PubMed-not-MEDLINE
pubmed:month
Sep
pubmed:issn
0032-0889
pubmed:author
pubmed:issnType
Print
pubmed:volume
100
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
261-6
pubmed:dateRevised
2010-9-14
pubmed:year
1992
pubmed:articleTitle
Effects of the Air Pollutant SO(2) on Leaves : Inhibition of Sulfite Oxidation in the Apoplast by Ascorbate and of Apoplastic Peroxidase by Sulfite.
pubmed:affiliation
Julius-von-Sachs-Institute of Biosciences, University of Würzburg, D-87 Würzburg, Germany.
pubmed:publicationType
Journal Article