Proteomic and activity profiles of ascorbate-glutathione cycle enzymes in germinating barley embryo

Birgit Christine Bønsager, Azar Shahpiri, Christine Finnie, Birte Svensson

    Research output: Contribution to journalJournal articleResearchpeer-review

    Abstract

    Enzymes involved in redox control are important during seed germination and seedling growth. Ascorbate-glutathione cycle enzymes in barley embryo extracts were monitored both by 2D-gel electrophoresis and activity measurements from 4 to 144 h post imbibition (PI). Strikingly different activity profiles were observed. No ascorbate peroxidase (APX) activity was present in mature seeds but activity was detected after 24 h PI and increased 14-fold up to 144 h PI. In contrast, dehydroascorbate reductase (DHAR) activity was present at 4 h PI and first decreased by 9-fold until 72 h PI followed by a 5-fold increase at 144 h PI. Glutathione reductase and monodehydroascorbate reductase activities were also detected at 4 h PI, and showed modest increases of 1.8- and 2.7-fold, respectively, by 144 h PI. The combination of functional analysis with the proteomics approach enabled correlation of the activity profiles and protein abundance. While gel spots containing APX showed intensity changes consistent with the activity profile from 0 to 72 h PI, DHAR spot intensities indicated that post-translational regulation may be responsible for the observed changes in activity. Transcript profiling, 20-western blotting and mass spectrometric characterization of multiple APX spots demonstrated the presence of APX1 and minor amounts of APX2.
    Original languageEnglish
    JournalPhytochemistry
    Volume71
    Issue number14-15
    Pages (from-to)1650-1656
    ISSN0031-9422
    DOIs
    Publication statusPublished - 2010

    Keywords

    • Cereal grain proteome
    • Two-dimensional gel electrophoresis
    • Seed germination
    • Redox regulation
    • Hordeum vulgare subsp vulgare
    • Enzyme assays

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