Glucose-6-phosphate, brain energy

The conclusdon that phosphate bond energy is used for the formation of ACh has been tested experimentally. ACh formation was already observed by Quastel and his colleagues (76). These authors demonstrated that ACh is formed in brain slices, i.e., in intact cells, but under aerobic conditions only and if glucose or pyruvate is present. In no other tissue was ACh synthesis found. The finer mechanism of the formation was not elucidated. 

Brain hexokinase is inhibited by its product glucose-6-phosphate and to a lesser extent by adenosine diphosphate. The isoenzyme of hexokinase found in brain may be soluble in the cytosol or be attached firmly to mitochondria [2 and references therein]. An equilibrium exists between the soluble and the bound enzyme. The binding changes the kinetic properties of hexokinase and its inhibition by Glc-6-P resulting in a more active enzyme. The extent of binding is inversely related to the ATP ADP ratio, i.e. conditions in which energy utilization... 

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