Feedback inhibition allows the control of metabolic pathways based on the production of the pathway’s product. This allows a defined concentration of product to be produced, before inducing the inhibition of the first enzyme in the pathway.
As enzymes (almost) always function at their maximal rate, it is possible to use the product of the pathway as an allosteric inhibitor. This is non-competitive, inhibiting enzyme function without interference from the substrate. This prevents wasteful (or futile) cycles from occurring in the cell, helping to preserve energy supplies.
One example is ATP synthesis and glycolysis. ATP acts as an allosteric inhibitor on the first enzyme in glycolysis, preventing the glycolytic pathway from occurring when adequate ATP is present in the cell.