[Analysis of allosteric mechanisms of suppressing parasitic recirculation in the futile cycle fructose-6-P--fructose-1,6-P2].

The uncontrollable substrate recirculation in the central futile cycle (FC) in the carbohydrate energy metabolism fructose-6-P (F6P) in equilibrium or formed from fructose-1,6-P2 (FBP), makes it impossible to maintain a stable level of ATP because of its wasteful expenditure in the cycle reactions which are equivalent to the ATPase reaction and also because of the diversion of FBP from glycolytic phosphorylation of ADP. It follows from the analysis of a mathematical model of the carbohydrate energy metabolism that the allosteric inhibition of fructosebisphosphatase (FBPase) by FBP and AMP leads to suppression of the recirculation in the FC and recovery of the ability of glycolysis to stabilize the level of ATP with high accuracy. The allosteric activation of phosphofrucktokinase (PFK) by AMP couples the expenditure of ATP and F6P in the FC with ATP consumption by a load.