Now, glycolysis involves many different enzymes and one important enzyme in glycolysis is Hexokinase. Hexokinase basically catalyzes the transformation of glucose into glucose six phosphate. Now, as the concentration of glucose six phosphate builds up, that glucose six phosphate basically binds to an allostericide on that enzyme, our hexokinase. And that deactivates it inhibits the activity of that enzyme. So let's suppose A is glucose and enzyme one is our hexokinase. So as hexokinase converts A into B, then binds onto enzyme A and that inactivates our enzyme.