Analysis of the Compartmentation of Glycolytic Intermediates, Nucleotides, Sugars, Organic Acids, Amino Acids, and Sugar Alcohols in Potato Tubers Using a Nonaqueous Fractionation Method
| Autor: | Eva M. Farré, Peter Geigenberger, Axel Tiessen, Lothar Willmitzer, Ute Roessner, Richard N. Trethewey |
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| Rok vydání: | 2001 |
| Předmět: |
Physiology
Metabolite Carboxylic Acids Plant Science Biology Cell Fractionation Pyrophosphate Gas Chromatography-Mass Spectrometry chemistry.chemical_compound Cytosol Sugar Alcohols Genetics Plastids Amino Acids Hexosephosphates Phosphorylation Pyrophosphatases Sugar Solanum tuberosum chemistry.chemical_classification Chromatography Nucleotides fungi food and beverages Metabolism Metabolic intermediate Cell Compartmentation Amino acid chemistry Biochemistry Vacuoles biology.protein Carbohydrate Metabolism Sucrose synthase Cell fractionation Research Article |
| Zdroj: | Plant Physiology. 127:685-700 |
| ISSN: | 1532-2548 0032-0889 |
| DOI: | 10.1104/pp.010280 |
| Popis: | The compartmentation of metabolism in heterotrophic plant tissues is poorly understood due to the lack of data on metabolite distributions and fluxes between subcellular organelles. The main reason for this is the lack of suitable experimental methods with which intracellular metabolism can be measured. Here, we describe a nonaqueous fractionation method that allows the subcellular distributions of metabolites in developing potato (Solanum tuberosum L. cv Desiree) tubers to be calculated. In addition, we have coupled this fractionation method to a recently described gas chromatography-mass spectrometry procedure that allows the measurement of a wide range of small metabolites. To calculate the subcellular metabolite concentrations, we have analyzed organelle volumes in growing potato tubers using electron microscopy. The relative volume distributions in tubers are very similar to the ones for source leaves. More than 60% of most sugars, sugar alcohols, organic acids, and amino acids were found in the vacuole, although the concentrations of these metabolites is often higher in the cytosol. Significant amounts of the substrates for starch biosynthesis, hexose phosphates, and ATP were found in the plastid. However, pyrophosphate was located almost exclusively in the cytosol. Calculation of the mass action ratios of sucrose synthase, UDP-glucose pyrophosphorylase, phosphoglucosisomerase, and phosphoglucomutase indicate that these enzymes are close to equilibrium in developing potato tubers. However, due to the low plastidic pyrophosphate concentration, the reaction catalyzed by ADP-glucose pyrophosphorylase was estimated to be far removed from equilibrium. |
| Databáze: | OpenAIRE |
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