Starch Degradation

Steup, Martin

doi:10.1016/b978-0-08-092615-5.50013-8

Cited by 74 publications

(69 citation statements)

References 242 publications

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“…These results indicate that in the normal, field-grown sweet potato plants, fl-amylase is present in significant amounts only in tuberous roots, as is the case for sporamin (17). However, we have not examined the presence of f3-amylase in other organs of the sweet potato such as flowers and seeds where relatively high f3-amylase activities are present in some plant species (25,27).…”

Section: Localization Of J8-amylase In the Sweet Potatomentioning

confidence: 95%

“…The precursor to the subunit of j3-amylase in sweet potato does not contain a presequence at its N terminus (30), suggesting that j3-amylase is localized outside of the plastids as are the fiamylases in vegetative tissues of other plants (13-15, 26, 30). Furthermore, ,B-amylase is unable to attack native starch granules without their prior digestion by other enzymes or solubilization by boiling (15,27). Therefore, it is unlikely that 3-amylase plays an essential role in the metabolism of transitorily accumulated and reserve starch within the plastid.…”

Section: Effects Of Various Sugars On Inductionmentioning

confidence: 99%

“…However, the presence of such a-glucans needs to be established (3,27), and the amount of j3-amylase that is synthesized seems to be more than sufficient for such a role. As an alternative explanation, Giese and Hejgaard (5) suggested that f3-amylase may have a nitrogen-storage function in barley seeds, since the profile of accumulation of ,B-amylase in developing seed resembles to that of the storage protein, hordein, and the synthesis of 3-amylase responds to increased supply of nitrogen.…”

Section: Effects Of Various Sugars On Inductionmentioning

confidence: 99%

“…Seeds of cereals and soybean contain a large amount ofB-amylase, and fl-amylase is also present in vegetative tissues of plants, for example, in leaves, roots, and cotyledons (27,28). Although #-amylase activity has been detected in chloroplasts from spinach leaves (23), several studies with other plants have 'Supported in part by Grants-in-Aid for Scientific Research on Priority Areas ("Totipotency of Plant Cells" and "Metabolite Accumulation in Higher Plants") from the Ministry of Education, Science and Culture, Japan.…”

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confidence: 99%

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Sucrose-Induced Accumulation of β-Amylase Occurs Concomitant with the Accumulation of Starch and Sporamin in Leaf-Petiole Cuttings of Sweet Potato

Nakamura¹,

Ohto²,

Yoshida³

et al. 1991

Plant Physiol.

107

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ABSTRACT,8-Amylase of sweet potato (Ipomoea batatas L.), which constitutes about 5% of the total soluble protein of the tuberous root, is absent or is present in only small amounts in organs other than the tuberous roots of the normal, field-grown plants. However, when leaf-petiole cuttings from such plants were supplied with a solution that contained sucrose, the accumulation of 8-amylase was induced in both leaf and petiole portions of the explants. The sucrose-induced accumulation of fl-amylase in leaf-petiole cuttings occurred concomitant with the accumulation of starch and of sporamin, the most abundant storage protein of the tuberous root. The accumulation of fl-amylase, of sporamin and of starch in the petioles showed similar dependence on the concentration of sucrose, and a 6% solution of sucrose gave the highest levels of induction when assayed after 7 days of treatment. The induction of mRNAs for f-amylase and sporamin in the petiole could be detected after 6 hours of treatment with sucrose, and the accumulation of j6-amylase and sporamin polypeptides, as well as that of starch, continued for a further 3 weeks. In addition to sucrose, glucose or fructose, but not mannitol or sorbitol, also induced the accumulation of fl-amylase and sporamin, suggesting that metabolic effects of sucrose are important in the mechanism of this induction. Treatment of leaf-petiole cuttings with water under continuous light, but not in darkness, also caused the accumulation of small amounts of these components in the petioles, probably as a result of the endogenous supply of sucrose by photosynthesis. These results suggest that the expression of the gene for f-amylase is under metabolic control which is coupled with the expression of sink function of cells in the sweet -otato.

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Section: Localization Of J8-amylase In the Sweet Potatomentioning

confidence: 95%

Section: Effects Of Various Sugars On Inductionmentioning

confidence: 99%

Section: Effects Of Various Sugars On Inductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Sucrose-Induced Accumulation of β-Amylase Occurs Concomitant with the Accumulation of Starch and Sporamin in Leaf-Petiole Cuttings of Sweet Potato

Nakamura¹,

Ohto²,

Yoshida³

et al. 1991

Plant Physiol.

107

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“…A situation that may be similar to that of debranching enzymes has been described for isoforms of starch phosphorylase in the germinating pea embryo. An isoform of phosphorylase revealed by immunofluorescence microscopy to be cytosolic contributes most of the activity of phosphorylase, and a plastidial isoform is confined to the small plastids, where it presumably cannot participate in starch degradation (Steup, 1988;van Berkel et al, 1991).…”

Section: Possible Roles Of Debranching Enzymes In Starch Metabolism Imentioning

confidence: 99%

Characterization of Starch-Debranching Enzymes in Pea Embryos

Zhu¹,

Hylton

Rössner

et al. 1998

Plant Physiology

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Two distinct types of debranching enzymes have been identified in developing pea (Pisum sativum L.) embryos using native gel analysis and tests of substrate preference on purified or partially purified activities. An isoamylase-like activity capable of hydrolyzing amylopectin and glycogen but not pullulan is present throughout development and is largely or entirely confined to the plastid. Activities capable of hydrolyzing pullulan are present both inside and outside of the plastid, and extraplastidial activity increases relative to the plastidial activity during development. Both types of debranching enzyme are also present in germinating embryos. We argue that debranching enzymes are likely to have a role in starch metabolism in the plastid of the developing embryo and in starch degradation during germination.

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Starch Biosynthesis. 3: The Glycogen Precursor Mechanism Using Phosphorylase in the Production of the Precursor Glycogen

Erlander¹

1998

Starch/Stärke

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nisms produce a glycogen precursor and both are dependent upon ADPGlu pp. The initial higher radioactivity of amylose and the constant yield of amylose can be explained by a three or four day biosynthesis of this glycogen, followed by the removal of the glycogen's exterior branches by debranching enzymes to produce amylose and amylopectin. These removed branches are first degraded (using SSS I and II) to ADPGlu, which is the only source of ADPGlu for amylose synthesis. The retention of the polymodal behavior of debranched amylopectin in going from Bomi to shx barley amylopectins is most likely due to a change from phosphorylase to SSS II since both debranched amylopectins produce Poisson distributions.

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Starch Degradation

Cited by 74 publications

References 242 publications

Sucrose-Induced Accumulation of β-Amylase Occurs Concomitant with the Accumulation of Starch and Sporamin in Leaf-Petiole Cuttings of Sweet Potato

Sucrose-Induced Accumulation of β-Amylase Occurs Concomitant with the Accumulation of Starch and Sporamin in Leaf-Petiole Cuttings of Sweet Potato

Characterization of Starch-Debranching Enzymes in Pea Embryos

Starch Biosynthesis. 3: The Glycogen Precursor Mechanism Using Phosphorylase in the Production of the Precursor Glycogen

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