Amplification of Control Signals

In glycolysis, the enzymes phosphofructokinase (PFK) and fructose 1,6-bisphosphatase (FBP) form a substrate cycle  

The enzymatic activity of PFK is increased and that of FBP is decreased by elevated concentrations of AMP. The following data were obtained for the fractional saturation (Chap. 9) of the two enzymes with AMP  

Calculate the change in flux through the pathway as [AMP] changes from 2.5 to 12.5 concentration units, assuming that the maximum enzymatic activities forPFK and FBPare 100 and 10 mmol L min-1, respectively that PFK is inactive in the absence of bound AMP and that FBP is inactive when it has bound AMP. 

PFK activity = maximum activity x proportion of enzyme with bound AMP while that for FBP is given by 

---