The mechanism of regulation of catalysis involves a change in enzyme activity without a change in the total amount of enzyme synthesized. Feedback regulation is a process in which the product of a reaction or a pathway inhibits its own production. For example, we take inhibition of the first reaction of glycolysis. During the initial stages of glycolysis, glucose convert in glucose 6-phosphate. Hexokinase enzyme use in this reaction and one ATP is also required. Increased concentration of glucose-6-phosphate inhibits the enzyme hexokinate and synthesis of glucose-6-phosphate become stop. In glycolysis when the concentration of glucose-6-phosphate decreases, enzyme hexokinase becomes active again.
The first irreversible reaction in a bio synthetic pathway is called the committed step and final product usually inhibits the enzymes. Which catalyses the committed step. The process in which an intermediate metabolic or an end product inhibits its own production is called as feedback inhibition or negative feed back control. In the branched metabolic pathway, the end-product can inhibit its own production or the production of all the other products. In such a case, the feedback inhibition would occur at the branch point. End product regulation at the initial stages of a reaction pathway has its own significance. Thus the accumulation of intermediate compounds which may not be required by the cell or organism is avoided. Also, since all the reactions dissipate some energy is wasted if intermediate reactions are inhibited.