Abstract
Properties of phosphoenolpyruvate (PEP) carboxylase (EC 4.1.1.31) obtained from isolated guard-cell protoplasts of Vicia faba L. were determined following rapidly desalting of the extract on a Sephadex G 25 column. The activity of PEP carboxylase was measured as a function of PEP and malate concentration, pH and K+ concentration within 2–3 min after homogenization of the guard-cell protoplasts. The activity of this enzyme was stimulated by PEP concentrations of 0.1 to 0.75 mM and by K+ ions (12 mM), but inhibited by PEP concentrations above 1 mM and by malate. Changes in the Km(PEP) and Vmax values with increasing malate concentrations (2.5 and 5 mM) indicate that the malate level, varying in relation to the physiological state of guard cells, plays an important role in regulating the properties of phosphoenolpyruvate carboxylase.
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Abbreviations
- CAM:
-
Crassulacean acid metabolism
- GCP:
-
guard-cell protoplast
- PEP:
-
phosphoenolpyruvate
References
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Dedicated to Professor Dr. Hubert Ziegler on the occasion of his 60th birthday
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Schnabl, H., Kottmeier, C. Properties of phosphoenolpyruvate carboxylase in desalted extracts from isolated guard-cell protoplasts. Planta 162, 220–225 (1984). https://doi.org/10.1007/BF00397443
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DOI: https://doi.org/10.1007/BF00397443