Characteristics of the sucrose uptake system of vacuoles isolated from red beet tissue. Kinetics and specifity of the sucrose uptake system |
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Authors: | J Willenbrink Sabine Doll |
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Institution: | (1) Botanisches Institut der Universität, Gyrhofstraße 15, D-5000 Köln 41, Germany |
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Abstract: | The uptake of sucrose against a concentration gradient into the dextran-impermeable 3H]H2O space of red beet (Beta vulgaris L.) vacuoles has been studied using silicone-layer-filtering centrifugation on both fluorometric and 14C-measurement of sucrose. Sucrose transport into vacuoles proceeds partly by an active transport system and partly by passive permeation. The K
M(20°C) for active sucrose uptake was found to be about 22 mM and the V
Max(20°C) was about 174 nmol sucrose x (unit betacyanin)-1 x h-1. The temperature dependency of sucrose transport appears to have an activation energy of 35,0 KJ×mol-1. Among various mono-, di-, and trisaccharides tested, raffinose acts as a competitive inhibitor of sucrose uptake.Abbreviations EDTA
ethylenediamine tetraacetic acid
- fr. wt.
fresh weight
- Tris
tris-(hydroxymethyl)-aminomethan |
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Keywords: | Beta Sucrose uptake Tonoplast Vacuole |
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