91Ó°ÊÓ

There are specific enzymes for different reactions of different substrates or molecules. Inhibition of an enzyme can cause the reaction to cease.

• Glycolysis and citric acid cycle are the pathways involve for the catabolism of a carbohydrate. The two pathways are connected and a certain inhibition of an enzyme would stop or slow down the whole process.

A citrate in the citric acid cycle is formed from oxaloacetate and acetyl-CoA. The citrate can go from the mitochondria to the cytosol. Citrate in the cytosol is a known inhibitor of phosphofructokinase-1, the rate-limiting enzyme in glycolysis. The inhibition of phosphofructokinase-1 by citrate signals enough energy in the system. Therefore, it signals the pathway that it can slow down the oxidation of glucose molecules for energy purposes.