Lock and Key Mechanism of Enzyme

In an enzyme-catalysed reaction, the starting molecule is called the substrate, and it is converted into a product. The substrate binds into a specially shaped pocket on the enzyme's surface, the active site - because the substrate fits the active site precisely, much as a key fits a specific lock, this model of enzyme action is called the lock and key mechanism. When the enzyme and substrate come together, they form a temporary enzyme-substrate (ES) complex. Within this complex, the substrate is raised in energy to an unstable, high-energy transition state; from this transition state, the reaction proceeds forward, breaking the substrate down into its product(s), while the enzyme itself is released unchanged and free to bind another substrate molecule. Reaching this transition state requires an input of energy called the activation energy, and the enzyme's wh …