In lock and key hypothesis, the shape and charge of the active site of the enzyme are specific and complementary to the shape and charge of the substrate.
Upon effective collision between the enzyme and substrate, the substrate will bind and form temporary bonds with the enzyme's active site to form an enzyme-substrate complex.
When reaction between substrates finished, products no longer fit into the active site and are expelled.
In induced fit hypothesis, the active site does not initially exist in shape and charge complementary to the substrate. When the substrate binds to the active site, the shape and charge of the active site changes to ensure a better fit.
