Enzymes speed up chemical reactions by lowering the activation energy needed for the reaction to occur. Activation energy is the energy barrier that reactants must overcome to be converted into products. By lowering this barrier, enzymes make it easier and faster for reactants to come together and react. Enzymes achieve this by binding to reactant molecules (called substrates) at a specific region called the active site. This binding brings the substrates into the correct orientation and proximity, reduces the energy needed to reach the transition state, and may also induce strain or change the shape of the substrates to favor the reaction. Importantly, enzymes do not change the overall energy levels of reactants or products, nor do they alter the reaction equilibrium; they simply speed up how fast equilibrium is reached. In summary, enzymes speed up reactions by acting as catalysts that lower activation energy through specific substrate binding and conformational changes, enabling biochemical reactions to occur rapidly enough to sustain life processes.
