par Malaisse, Willy 
;Bodur, Hakan
Référence International Journal of Biochemistry, 23, 12, page (1471-1481)
Publication Publié, 1991
;Bodur, Hakan Référence International Journal of Biochemistry, 23, 12, page (1471-1481)
Publication Publié, 1991
Article révisé par les pairs
| Résumé : | The fate of unlabelled D-glucose and D-[2-3H]glucose in pancreatic islets was simulated taking into account experimental values for glycolytic flux, intracellular concentration of D-glucose 6-phosphate and phosphoglucoisomerase activity. The model, which also takes into account the isotopic discrimination in velocity and intramolecular transfer of tritium between D-[2-3H]glucose 6-phosphate and D-[1-3H]fructose 6-phosphate in the reaction catalyzed by phosphoglucoisomerase, revaled that the predicted generation of 3HOH from D-[2-3H]glucose was much higher than the true experimental value. Such a discrepancy is reinforced by the consideration that the generation of 3HOH from D-[2-3H]glucose in islet cells is not solely attributable to the phosphoglucoisomerase-catalyzed detritiation of hexose 6-phosphates metabolized in the glycolytic pathway. In order to reconcile experimental and theoretical values for 3HOH production, it was found necessary to postulate enzyme-to-enzyme tunnelling of hexose 6-phosphates in the hexokinase/phosphoglucoisomerase/phosphofructokinase sequence. It is proposed that such a tunnelling may favour the anomeric specificity of D-glucose metbolism in islet cells, by restricting the anomerization of hexose 6-phosphates. |
