Hexose metabolism in pancreatic islets (time course of 3HOH production from tritiated D-glucose in models with and without enzyme-to-enzyme tunnelling).

The fate of D-[2-3H] glucose and D-[5-3H] glucose in pancreatic islets was simulated in models with or without enzyme-to-enzyme tunnelling of hexose 6-phosphates in the glycolytic cascade. Satisfactory values for the recovery of phosphoglucoisomerase activity, for the ratio between unlabelled D-glucose 6-phosphate and D-fructose 6-phosphate, and for the time course of both 3HOH production from D-[2-3H] glucose and tritiated D-fructose 1,6-bisphosphate generation from D-[5-3H] glucose were only reached in models with enzyme-to-enzyme tunnelling, with emphasis on the coupling between phosphoglucoisomerase and phosphofructokinase.