According to the hypothesis, like a lock can be open by its key only, a substance possessing specific composition only can combine with the specific active site found in the specific enzyme’s surface.
The molecules on which the activities of the enzymes take place are called substrates.
The substrates possessing accurate geometric configuration can fit within the enzyme’s active site.
The enzyme’s active site is highly specific to the surface of the substrate.
The substrate and the enzyme fit like a lock and key, providing a lock and key enzyme action model.
Some of the molecules, which compete with the substrate can either cease or slow down the reaction. These substances are called competitive inhibitors.
