Determination of the starch-phosphorylating enzyme activity in plant extracts

G. Ritte, M. Steup, J. Kossmann, J.R. Lloyd

    Research output: Contribution to journalJournal articleResearchpeer-review

    Abstract

    For quantification of alpha-glucan, water dikinase(GWD) activity in crude extracts of plant tissues a radio-labeling assay was established that uses soluble starch and P-33-labeled ATP as phosphate acceptor and donor, respectively. A constant rate of starch labeling was observed only if the ATP applied was labeled at the beta position. In wild-type extracts from leaves of Arabidopsis thaliana (L.) Heynh. the maximum rate of starch phosphorylation was approximately 27 pmol min(-1) (mg protein)(-1). Leaf extracts from the GWD-deficient sex1 mutants of Arabidopsis showed no significant incorporation of phosphate whereas extracts from potato (Solanum tuberosum L.) tuber expressing a GWD antisense construct exhibited less activity than the wild-type control. To our knowledge this is the first time that a quantification of the starch-phosphorylating activity has been achieved in plant crude extracts.
    Original languageEnglish
    JournalPlanta
    Volume216
    Issue number5
    Pages (from-to)798-801
    ISSN0032-0935
    DOIs
    Publication statusPublished - 2003

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