This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Web of Science (54) Citing Articles via Google Scholar Google Scholar Articles by Stitt, M. Search for Related Content PubMed PubMed Citation Articles by Stitt, M. Agricola Articles by Stitt, M.

Metabolism and Enzymology

Product Inhibition of Potato Tuber Pyrophosphate:Fructose-6-Phosphate Phosphotransferase by Phosphate and Pyrophosphate ¹

Lehrstuhl für Pflanzenphysiologie, Universität Bayreuth, 8580 Bayreuth, Federal Republic of Germany

The product inhibition of potato (Solanum tuberosum) tuber pyrophosphate:fructose-6-phosphate phosphotransferase by inorganic pyrophosphate and inorganic phosphate has been studied. The binding of substrates for the forward (glycolytic) and the reverse (gluconeogenic) reaction is random order, and occurs with only weak competition between the substrate pair fructose-6-phosphate and pyrophosphate, and between the substrate pair fructose-1,6-bisphosphate and phosphate. Pyrophosphate is a powerful inhibitor of the reverse reaction, acting competitively to fructose-1,6-biphosphate and noncompetitively to phosphate. At the concentrations needed for catalysis of the reverse reaction, phosphate inhibits the forward reaction in a largely noncompetitive mode with respect to both fructose-6-phosphate and pyrophosphate. At higher concentrations, phosphate inhibits both the forward and the reverse reaction by decreasing the affinity for fructose-2,6-bisphosphate and thus, for the other three substrates. These results allow a model to be proposed, which describes the interactions between the substrates at the catalytic site. They also suggest the enzyme may be regulated in vivo by changes of the relation between metabolites and phosphate and could act as a means of controlling the cytosolic pyrophosphate concentration.

This article has been cited by other articles:

				L.-S. CHEN and A. NOSE Day-Night Changes of Energy-rich Compounds in Crassulacean Acid Metabolism (CAM) Species Utilizing Hexose and Starch Ann. Bot., September 1, 2004; 94(3): 449 - 455. [Abstract] [Full Text] [PDF]

				S. J. Trevanion Photosynthetic carbohydrate metabolism in wheat (Triticum aestivum L.) leaves: optimization of methods for determination of fructose 2,6-bisphosphate J. Exp. Bot., June 1, 2000; 51(347): 1037 - 1045. [Abstract] [Full Text] [PDF]

				J. Gibbs, S. Morrell, A Valdez, T.L Setter, and H. Greenway Regulation of alcoholic fermentation in coleoptiles of two rice cultivars differing in tolerance to anoxia J. Exp. Bot., April 1, 2000; 51(345): 785 - 796. [Abstract] [Full Text] [PDF]

				A. Roscher, L. Emsley, P. Raymond, and C. Roby Unidirectional Steady State Rates of Central Metabolism Enzymes Measured Simultaneously in a Living Plant Tissue J. Biol. Chem., September 25, 1998; 273(39): 25053 - 25061. [Abstract] [Full Text] [PDF]