How does negative feedback control a metabolic pathway?

Negative feedback, often referred to as feedback inhibition, is a regulatory mechanism that controls the flux of metabolites through a biochemical pathway by limiting the production of substances to optimal levels.12

In this process, the end product of a metabolic pathway acts as an inhibitor for a key pacemaker enzyme that typically catalyzes the first unique step of that pathway. When the concentration of the end product reaches a critical level, it binds to a regulatory site on the enzyme—distinct from the active site—known as an allosteric site.234

This interaction induces a change in the enzyme's shape, which deforms the active site and prevents it from binding to its substrate. By inhibiting this early step, the cell effectively slows or halts the entire sequence of reactions, preventing the overproduction of the substance. Once the product is consumed or broken down, the inhibition is relaxed, allowing the pathway to resume activity. This system ensures that the cell synthesizes only the amount of product it requires, maintaining metabolic balance.4312