Mechanism of Enzyme Action

Enzymes are biocatalysts that catalyse one specific biochemical reaction. In general, an enzyme speeds up its reaction by reducing the activation energy of that reaction, achieved by stabilising the high-energy transition state that the reacting molecules must pass through. In a typical enzyme-catalysed reaction, the enzyme (E) binds reversibly with its substrate molecule (S) to form an enzyme-substrate complex (ES): E + S ⇌ [ES]. While bound in this complex, the substrate is converted into product; the enzyme itself is then released unchanged and free to bind another substrate molecule ([ES] → E + P). This picture of a substrate fitting into and being processed by a complementary enzyme is known as the lock-and-key model of en …