Enzymes are classified as catalysts because these biomolecules accelerate chemical reactions allowing molecules to overcome the activation barrier at a lower energy level. An enzyme (E) interacts with molecule A to form a new complex compound KA. It represents a transition state with lower activation energy compared to the transition state of molecule A in the non-catalyzed reaction. Then the molecule-enzyme (EA) complex decomposes into product P and a free enzyme, which can again combine with another molecule A and repeat the entire cycle. As a result, in this way, enzymes similar to catalysts reduce the activation energy of a chemical reaction.