A Kinetic Study of Pyrophosphate: Fructose‐6‐Phosphate Phosphotransferase from Potato Tubers

FEBS Journal - Tập 129 Số 1 - Trang 191-195 - 1982
Emile Van Schaftingen1, B Lederer1, Ramón Bartrons1, H G Hers1
1Laboratoire de Chimie Physiologique, de I'Université Catholique de Louvain, UCL 7539, and International Institute of Cellular and Molecular Pathology. Avenue Hippocrate 75, B-1200 Bruxelles, Belgium

Tóm tắt

Pyrophosphate: fructose‐6‐phosphate phosphotransferase (PPi‐PFK) has been purified 150‐fold from potato tubers and the kinetic properties of the purified enzyme have been investigated both in the forward and the reverse direction. Saturation curves for fructose 6‐phosphate and also for fructose 1,6‐bisphosphate were sigmoidal whereas those for PPi and Pi were hyperbolic. In the presence of fructose 2,6‐bisphosphate, the affinity for fructose 6‐phosphate and for fructose 1,6‐bisphosphate were greatly increased and the kinetics became Michaëlian. The effect of fructose 2,6‐bisphosphate was increased by the presence of fructose 6‐phosphate and decreased by the presence of Pi. Consequently, the Ka for fructose 2,6‐bisphosphate was as low as 5 nM for the forward reaction and reached 150 nM for the reverse reaction. On the basis of these properties, a procedure allowing one to measure fructose 2,6‐bisphosphate in amounts lower than a picomole, is described.

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FEBS Journal

Tập 129 Số 1

191-195

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