Phosphate esters in amylopectin clusters of potato tuber starch

Jeanette Wikman, Flemming Hofmann Larsen, Mohammed Saddik Motawie, Andreas Blennow, Eric Bertoft

    25 Citations (Scopus)
    2 Downloads (Pure)

    Abstract

    Starch phosphate is important in starch metabolism and in order to deduce its location and structural effects in clusters and building blocks of amylopectin, these were isolated from a normal potato (WT) and two starches with antisense suppressed glucan water dikinase (asGWD) activity and starch branching enzyme (asSBE) activity possessing suppressed and increased phosphate contents, respectively. Neutral N-chains and phosphorylated P-chains of the amylopectin macromolecules were similar in WT and asGWD, whereas asSBE possessed considerably longer P-chains. Cluster β-limit dextrins were isolated by α-amylase treatment and successive β-amylolysis. Cluster sizes were generally smaller in asSBE. The building block composition of neutral N-clusters were very similar in WT and asGWD, while asSBE was different, containing less blocks with degree of polymerization (DP) > 14. Phosphate content of the P-clusters of WT and asGWD was rather similar, while asSBE contained highly phosphorylated P-clusters with proportionally more P-chains and a low degree of branching. The average chain lengths of the P-clusters were, however, similar in all samples. Our data demonstrate only minor effect on the cluster structure in relation to phosphate deposition suggesting conserved reaction patterns of starch phosphorylation. Models are suggested to account for the principle structural and functional effects of starch phosphate esters.

    Original languageEnglish
    JournalInternational Journal of Biological Macromolecules
    Volume48
    Issue number4
    Pages (from-to)639-649
    Number of pages11
    ISSN0141-8130
    DOIs
    Publication statusPublished - 1 May 2011

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