Abstract
3-Mercaptopicolinic acid, a non-competitive inhibitor of phosphoenolpyruvate carboxykinase (EC 4.1.1.19) was used to study the control of gluconeogenesis by this enzyme in germinating marrow (Cucurbita pepo) cotyledons. In vitro, phosphoenolpyruvate carboxykinase was inhibited by 3-mercaptopicolinic acid, with aKi of 5.9 μM. At 25°C the inhibitor caused an increase in the label incorporated from [2-14C]acetate into CO2, and a decrease in the label incorporated into the insoluble and neutral fractions. Phosphoenolpyruvate carboxykinase had a flux control coefficient for gluconeogenesis (C J PEPCK ) of between 0.7 and 1.0. 3-Mercaptopicolinic acid was a less effective inhibitor of phosphoenolpyruvate carboxykinase at lower temperatures (Ki = 8.6 μM at 17°C, 13.3 μM at 10°C) and had similar effects on the metabolism of [2-14C]acetate by marrow cotyledons when the temperature was reduced to 17°C and 10°C. The control coefficient for this enzyme did not change with temperature, indicating that phosphoenolpyruvate carboxykinase exerts a high degree of control over gluconeogenesis at all temperatures examined.
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Abbreviations
- PEP:
-
Phosphoenolpyruvate
- PEPCK:
-
PEP carboxykinase
References
Akerboom, T.P.M. (1979) Compartmentation of adenine nucleotides in rat hepatocytes. Ph.D. thesis, University of Amsterdam, Krips Repro, Meppel
ap Rees, T., Thomas, S.M., Fuller, W.A., Chapman, B. (1974) The relationship between gluconeogenesis and carbohydrate oxidation in higher plants. In: Plant carbohydrate biochemistry, pp. 27–46, Pridham, J.B., ed. Academic Press, London
ap Rees, T., Thomas S.M., Fuller, W.A., Chapman, B. (1975) Location of gluconeogenesis from phosphoenolpyruvate in cotyledons ofCucurbita pepo. Biochim. Biophys. Acta385, 145–156
Breidenbach, R.W., Beevers, H. (1967) Association of the glyoxylate cycle enzymes in a novel subcellular particle from castor bean endosperm. Biochem. Biophys. Res. Commun.27, 462–469
Cooper, T.G., Beevers, H. (1969) Mitochondria and glyoxysomes from castor bean endosperm. Enzyme constituents and catalytic capacity. J. Biol. Chem.244, 3507–3513
Groen, A.K., van der Meer, R., Westerhoff, H.V., Wanders, R.J.A., Akerboom, T.P.M., Tager, J.M. (1982) Control of metabolic fluxes. In: Metabolic Compartmentation pp. 9–37, Sies, H. ed. Academic Press, London
Jomain-Baum, M., Schramm, V.L., Hanson, R.W. (1976) Mechanism of 3-mercaptopicolinic acid inhibition of hepatic phosphoenol-pyruvate carboxykinase (GTP). J. Biol. Chem.251, 37–44
Kacser, H., Burns, J.A. (1973) The control of flux. Symp. Soc. Exp. Biol.27, 65–104
Leegood, R.C., ap Rees, T. (1978a) Phosphoenolpyruvate carboxykinase and gluconeogenesis in cotyledons ofCucurbita pepo. Biochim. Biophys. Acta.524, 207–218
Leegood, R.C., ap Rees, T. (1978b) Identification of the regulatory steps in gluconeogenesis in cotyledons ofCucurbita pepo. Biochim. Biophys. Acta.542, 1–11
Nishimura, M., Beevers, H. (1979) Subcellular distribution of gluconeogenic enzymes in germinating castor bean endosperm. Plant Physiol.64, 31–37
Rognstad, R. (1979) Rate limiting steps in metabolic pathways. J. Biol. Chem.254, 1875–1878
Stitt, M., Huber, S., Kerr, P. (1987) Control of photosynthetic sucrose formation. In: The biochemistry of plants vol. 10, pp. 327–409, Hatch, M.D., Boardman, N.K., eds. Academic Press, London
Thomas, S.M., ap Rees, T. (1972) Gluconeogenesis during the germination ofCucurbita pepo Phytochemistry11, 2177–2185
Trevanion, S.J., Brooks, A.L., Leegood, R.C. (1995) The effect of temperature on the growth and metabolism of germinating cotyledons of marrow (Cucurbita pepo L.). J. Plant Physiol., in press
Walker, R.P., Trevanion, S.J., Leegood, R.C. (1995) Phosphoenolpyruvate carboxykinase from higher plants: Purification from cucumber and evidence of rapid proteolytic cleavage in extracts from a range of plant tissues. Planta196, 58–63
Youle, R.J., Huang, A.H.C. (1976) Development and properties of fructose 1,6-bisphosphatase in the endosperm of castor bean seedlings. Biochem. J.154, 647–652
Ziegler, H. (1975) Nature of transported substances. In: Encyclopedia of plant physiology, vol. 1, pp. 59–100, Zimmerman, M., Milburn, J. eds. Springer-Verlag, Berlin
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The authors thank Dr. Ian Woodrow (University of Melbourne, Australia) for helpful discussions. This work was supported by a grant from the Science and Engineering Research Council, U.K. (GR/F 50978).
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Trevanion, S.J., Brooks, A.L. & Leegood, R.C. Control of gluconeogenesis by phosphoenolpyruvate carboxykinase in cotyledons ofCucurbita pepo L.. Planta 196, 653–658 (1995). https://doi.org/10.1007/BF01106757
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DOI: https://doi.org/10.1007/BF01106757