If the NADH is bound instead of the NAD plus step three A cannot take place. And so because that happens, because the NADH kicks off, the NAD plus the isocytrate dehydrogenase enzyme cannot carry out its function. So we see that if we have high levels of ATP, a high energy charge value, we will not need to generate any more ATP. In fact, ATP will act as an allosteric inhibitor of isocytrade dehydrogenase, and that will decrease the affinity for the substrate. In addition, the NADH will kick off the NAD plus that is needed for step three A to take place, and that will inhibit the activity of ISOC citrate dehydrogenase, decrease the rate at which this step actually takes place, and that will decrease the rate of the citric acid cycle. So let's take a look at the following diagram to see exactly what we mean.