Symplasmic and apoplasmic radial ion transport in plant roots |
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Authors: | Frank van Iren Pinie Boers-van der Sluijs |
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Institution: | (1) Fachbereich Chemie (Biochemie) der Philipps-Universität, Lahnberge, D-3550 Marburg, Germany |
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Abstract: | Enzymes of starch synthesis and degradation were identified in crude extracts of the unicellular green alga Dunaliella marina (Volvocales). By polyacrylamide gel electrophoresis and specific staining for enzyme activities, 4 multiple forms of starch synthase, 2 amylases, and at least 2 forms of -glucan phosphorylase were visible. Using specific -glucans incorporated into the gel before electrophoresis we have tentatively correlated -amylase and -amylase with both hydrolytic activities. The activities of -glucan phosphorylase and amylase(s) were measured quantitatively in crude extracts, and the concomitant action of -glucan phosphorylase and amylase(s) was found to account for the fastest rate of starch mobilization observed in vivo. Isolated chloroplasts retained both typical plastid marker enzymes and ADPglucose pyrophosphorylase, starch synthase, amylase(s), and -glucan phosphorylase to a similar percentage. Gel electrophoretic analysis followed by staining for enzyme activity of a stromal fraction resulted in a pattern of multiple forms of starch-metabolizing enzymes analogous to that found in a crude extract. We interpret the combined data as indicating the exclusive location in vivo of starch-metabolizing enzymes in chloroplasts of D. marina.Abbreviations Chl
chlorophyll
- DEAE-dextran
diethylaminoethyl-dextran
- DDT
dithiothreitol
- EDTA
ethylenediamine tetraacetic acid
- FBPase
fructose-1,6-bisphosphate phosphatase, EC 3.1.3.11
- G1P
glucose 1-phosphate
- G6P-DH
glucose 6-phosphate dehydrogenase, EC 1.1.1.49
- HEPES
N-2-hydroxyethylpiperazine-N -ethanesulphonic acid
- MES
2-(N-morpholino)ethanesulphonic acid
- Pi
inorganic orthophosphate
- RuBP carboxylase
ribulose-1,5-bisphosphate carboxylase, EC 4.1.1.39 |
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Keywords: | ADPglucose pyrophosphorylase Chloroplast Enzyme compartmentation Enzymes multiple -Glucan phosphorylase" target="_blank">gif" alt="agr" align="BASELINE" BORDER="0">-Glucan phosphorylase Starch metabolism |
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